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Exposure based intervention compared to stimulus control
as a treatment for Hair-pulling disorder and Skin-picking
disorder
A clinical controlled trial
Lárus Valur Kristjánsson
Lokaverkefni til cand. psych.-gráðu
Sálfræðideild
Heilbrigðisvísindasvið
Berskjöldunarmiðað inngrip samanborið við áreitastjórnun sem meðferð
við Hárreyti- og Húðkroppunaráráttu
Lárus Valur Kristjánsson
Lokaverkefni til cand. psych. gráðu
Leiðbeinendur: Ragnar Pétur Ólafsson og Ívar Snorrason
Sálfræðideild
Heilbrigðisvísindasvið Háskóla Íslands
Júní 2017
Exposure based intervention compared to stimulus control as a treatment
for Hair-pulling disorder and Skin-picking disorder
Lárus Valur Kristjánsson
Thesis for the degree of Cand. Psych.
Supervisors: Ragnar Pétur Ólafsson og Ívar Snorrason
Department of Psychology
School of Health Sciences
June 2017
Ritgerð þessi er lokaverkefni til cand. psych. gráðu í sálfræði og er óheimilt að afrita ritgerðina nema með leyfi rétthafa.
© Lárus Valur Kristjánsson 2017
Prentun: Háskólaprent, 2017
Reykjavík, Ísland 2007
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Útdráttur
Markmið: Hárreyti- (Hair-pulling disorder; HPD) og húðkroppunarröskun (Skin-picking
disorder; SPD) eru tiltölulega algengar raskanir sem geta orðið að langvarandi vanda ef
viðeigandi meðferð er ekki veitt. Algengasta meðferðin sem einstaklingar með þessar
raskanir fá er serótónínvirk lyfjameðferð sem oft sýnir lítinn sem engan árangur. Meðferð við
þessum röskunum er lítið rannsökuð og vöntun er á gagnreyndum meðferðarinngripum.
Markmið rannsóknar var að athuga árangur vísbenda-berskjöldunar með svarhömlun (e. cue-
exposure with response prevention; CERP) sem meðferðarinngrip við HPD og SPD. Habit
reversal þjálfun (e. Habit Reversal Training; HRT) ásamt CERP var því borin saman við
HRT með áreitastjórnun (e. stimulus control; SC) sem er kjörmeðferð við þessum kvillum.
Aðferð: Þátttakendur voru 20 háskólanemar sem uppfylltu greiningarskilmerki fyrir annað
hvort HPD (n=5) eða SPD (n=15). Þeim var raðað í meðferðarinngripin af handahófi. Allir
þátttakendur fengu fjórar meðferðastundir þar sem tíu fengu HRT-CERP og tíu fengu HRT-
SC. Þátttakendur mættu einnig í upplýsingaviðtal bæði fyrir og eftir meðferðarinngrip auk
eftirfylgdarviðtals í gegnum síma einum mánuði síðar.
Niðurstöður: Niðurstöður sýndu að það dróg verulega úr alvarleika einkenna í kjölfar
meðferðar í báðum hópunum. Munur á meðferðarhópum var ekki marktækur þegar árangur
var metinn með sjálfsmatskvörðum en reyndist marktækur þegar árangur var metinn í
viðtölum og var HRT-CERP þá árangursríkari. Áhrifastærðir (Cohen‘s d) voru ívið hærri í
HRT-CERP hópnum (2.27-2.96) samanborið við HRT-SC (1.28-1.30) á öllum mælitækjum.
Ályktanir: Niðurstöður þessarar rannsóknar benda til að HRT-CERP sé áhrifaríkt
meðferðarinngrip við hárreyti- og húðkroppunarröskun, sem ætti að þróa frekar. Mikilvægt er
meðal annars að meta árangur meðferðarinnar í fjölbreyttara og stærra úrtaki þar sem allir
þátttakendur í þessari rannsókn voru konur og háskólanemar.
Efnisorð: Hárreytiröskun, húðkroppunarröskun, áreitastjórnun, vísbenda-berskjöldun, Habit reversal þjálfun, samanburðarrannsókn.
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Abstract
Objective: Hair-pulling disorder (HPD or trichotillomania) and Skin-picking disorder (SPD
or excoriation disorder) are relatively common psychiatric problems with significant public
health impact, and may have a chronic course if left untreated. The most common treatment
for individuals with HPD/SPD is SSRI medications, but is largely ineffective. The objective
of this study was to examine the efficacy of cue-exposure with response prevention (CERP)
for HPD/SPD. Habit Reversal Training (HRT), implemented with CERP, was compared to
HRT implemented with stimulus control (SC), which is the first-line treatment for HPD and
SPD.
Method: Participants were 20 university students diagnosed with either HPD (n=5) or SPD
(n=15). They were randomized to receive four one-hour weekly sessions with either HRT-
CERP (n=10) or HRT-SC (n=10). Assessment interviews took place pre- and post-treatment
and after one month follow-up.
Results: A significant reduction in symptom severity was observed in both treatment groups
on all primary outcome measures. No significant group differences were observed on self-
report scales but significant differences were found on interview-based measures with HRT-
CERP being more effective than HRT-SC in reducing symptom severity. Effect sizes
(Cohen’s d) were larger in HRT-CERP (2.27-2.96) compared to HRT-SC (1.28-1.30) on all
primary outcome measures.
Conclusions: HRT-CERP seems to be an effective treatment strategy for individuals with
HPD and SPD when compared to HRT-SC, and should be developed further for this patient
group. The sample in the present study was homogeneous in nature, with all participants
being female and university students. This should be addressed in future studies.
Keywords: Hair-pulling disorder, Skin-picking disorder, Habit Reversal Training, cue exposure, stimulus control, randomized clinical trial.
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Acknowledgements
I would like to take this opportunity to thank my supervisors, Ragnar Pétur Ólafsson and Ívar
Snorrason, for excellent guidance and supervision throughout this entire process. I also want
to thank my research partner, Hulda María Einarsdóttir, for great collaboration. Finally, I
would like to thank my wonderful and extremely patient girlfriend, Harpa Rún Glad, for all
the support and love.
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Table of Contents
Útdráttur ..................................................................................................................................... 3
Abstract ...................................................................................................................................... 4
Acknowledgements .................................................................................................................... 5
Table of Contents ....................................................................................................................... 6
Introduction ................................................................................................................................ 8
Hair-pulling disorder (Trichotillomania) ............................................................................................ 9
Excoriation (skin-picking) disorder .................................................................................................... 9
The relatedness of HPD and SPD ..................................................................................................... 10
Treatments for HPD and SPD ........................................................................................................... 11
Habit Reversal Training (HRT) .................................................................................................... 12
Stimulus control (SC). .................................................................................................................. 12
Cue-exposure/response prevention (CERP). ................................................................................. 13
Purpose of the present study ............................................................................................................. 14
Method ..................................................................................................................................... 16
Participants ............................................................................................................................... 16
.......................................................................................................................................................... 17
Measures ........................................................................................................................................... 17
Phone screen. ................................................................................................................................ 17
Psychiatric interviews. .................................................................................................................. 17
Self-Report Measures for SPD. ..................................................................................................... 18
Self-Report Measures for HPD. .................................................................................................... 19
Other self-report measures. ........................................................................................................... 20
Procedure .......................................................................................................................................... 21
Treatments. .................................................................................................................................... 22
Phone follow-up ................................................................................................................................ 24
Therapists .......................................................................................................................................... 24
Statistical Analysis ............................................................................................................................ 24
Results ...................................................................................................................................... 26
Pre-treatment Comparisons ............................................................................................................... 26
Demographic and clinical characteristics...................................................................................... 26
Depression, anxiety, and stress (DASS-21). ................................................................................. 27
Symptom severity. ........................................................................................................................ 27
Treatment Efficacy ............................................................................................................................ 28
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Correlation between primary outcome measures. ......................................................................... 28
SPS-R/MGH-HS self-report scales. .............................................................................................. 28
SPS-R-IV/MGH-HS-IV interview. ............................................................................................... 28
CGI scores. .................................................................................................................................... 29
Session-by-session self-report mean scores. ................................................................................. 29
Other outcomes ................................................................................................................................. 30
DASS-21. ...................................................................................................................................... 30
Cue-reactivity. ............................................................................................................................... 30
SPRS/HPRS ‘Wanting’ and ‘Liking’ subscale scores. ................................................................. 30
Discussion ................................................................................................................................ 32
CERP vs SC in preventing relapse .................................................................................................... 32
Cue-reactivity. ............................................................................................................................... 33
Automatic versus focused behavior. ............................................................................................. 34
Limitations ........................................................................................................................................ 34
Strengths ........................................................................................................................................... 35
Conclusions ....................................................................................................................................... 35
References ................................................................................................................................ 36
Appendix .................................................................................................................................. 45
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Introduction
Hair-pulling disorder (HPD; trichotillomania) and excoriation (skin-picking) disorder (SPD)
are both categorized as obsessive-compulsive and related disorders in DSM-5 (American
Psychiatric Association [APA], 2013). More specifically these disorders are often
characterized as body-focused repetitive behaviors (BFRB) (Grant, Stein, Woods, &
Keuthen, 2012) that is an umbrella term for compulsive behaviors directed toward one’s body
(Teng, Woods, Twohig, & Marcks, 2002). For many people with BFRB, hair pulling and skin
picking causes merely a frustration, but for some it results in great emotional distress and
impairment (Diefenbach, Tolin, Hannan, Crocetto, & Worhunsky, 2005; Odlaug, Kim, &
Grant, 2010; Snorrason, 2008). Both HPD and SPD are relatively common and sometimes
severe psychiatric problems with significant health impact, but have not received much
research attention (e.g. Snorrason et al., 2012). However, interest of researchers in HPD and
SPD has grown considerably the past 10 years (Grant et al., 2012).
The diagnostic criteria for both disorders are almost identical, the only difference
being what part of the body the behavior is directed at. To be diagnosed with either disorder,
the behavior must result in distress or interference in any life area (e.g. relationships,
school/work etc.) (e.g. APA, 2013; Bohne, Keuthen, & Wilhelm, 2005; Bohne, Wilhelm,
Keuthen, Baer, & Jenike, 2002) and the behavior is not better explained by symptoms of
another mental disorder or other medical conditions (APA, 2013). The 12-month prevalence
for HPD, in general population, is estimated to be 1-2% in adults and adolescents and the
disorder seems to affect females more frequently than males, at a ratio of 10:1 (APA, 2013).
The lifetime prevalence of SPD in general population is estimated to be 2-4.6% (Arnold,
Auchenbach, & McElroy, 2001; Bohne et.al., 2002; Keuthen et.al., 2000). Most SPD patients,
at least in clinical populations, are female (75-94%) and the most common age of onset is in
adolescent years (Snorrason, Belleau, & Woods, 2012).
Clinicians have differentiated between automatic and focused picking and pulling.
Focused behavior involves conscious picking/pulling that often seems to be a reaction to
unpleasant sensory, emotional and/or cognitive state (e.g., anxiety, boredom). Automatic
behavior involves habitual picking/pulling that, in contrast, occurs out of the awareness of the
patient (du Tiot, van Kredenburg, Niehaus, & Stein, 2001; Flessner, Woods, Franklin, 2008).
Even though this differentiation is convenient, these behavior styles tend to co-occur, and
overlap within patients and are rarely mutually exclusive (Duke, Keeley, Ricketts, Geffken,
& Storch, 2010). Nonetheless, this difference might influence treatment effectiveness
(Flessner et al., 2008; Walter, Flessner, Conelea, & Woods, 2009).
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The most common treatment that individuals with HPD and SPD receive is SSRI
medication (Marks, Wetterneck, & Woods, 2006) but data shows that those medications are
often ineffective (Bloch et al., 2007). Different psychological treatments have been used to
treat HPD and SPD, for example; hypnosis, psychoanalysis, cognitive therapy, and
behavioral therapy (Marks et al., 20016; Snorrason & Björgvinsson, 2012). Cognitive
behavioral treatments (CBT) have been recommended as first line intervention for HPD and
SPD (Flessner, Board, Penzel, & Keuthen, 2010) but only one type of behavior therapy,
Habit reversal training (HRT), has been assessed in comparative studies (Snorrason &
Björgvinsson, 2012).
In this essay clinical characteristics of HPD and SPD will be described, as well as the
similarities in symptom presentation and phenomenology of both disorders. The most
common types of cognitive behavioral treatments will be discussed, including Habit Reversal
Training (HRT), stimulus control (SC) and cue exposure/response prevention (CERP).
Finally, the results of a recently completed research trial will be described, where the
effectiveness of HRT-CERP and HRT-SC for HPD and SPD was compared.
Hair-pulling disorder (Trichotillomania)
Hair-pulling disorder is characterized by repetitive pulling, and persistent inability to
resist pulling out one‘s hair (APA, 2013). The hair-pull can take place at any location on the
body where there is hair but the most common pulling areas include the scalp, eyebrows,
eyelashes, pubic region and legs (Duke, Keeley, Geffken & Storch, 2010; Woods et al.,
2006). It is common that many patients engage in a variety of habitual behaviors both before
and after pulling, for example searching for the perfect hair or eating the hair afterwards
(Mansueto, Stemberger, Thomas, & Golomb, 1997).
HPD can cause significant distress and dysfunction (Lootens, & Nelson-Gray, 2016).
Negative consequences of HPD can include bald spots, hair thinning, disruption in work or
academic functioning and social avoidance (Diefenbach et al., 2005; Woods et al., 2006).
According to Odlaug et al. (2010) individuals with HPD experience a lower quality of life
compared to controls. They also demonstrated lower self-esteem compared with non-
psychiatric control group, even after controlling for depression (Diefenbach et al., 2005).
Excoriation (skin-picking) disorder
SPD is characterized by excessive picking at one’s own skin (APA, 2013). Individuals
often use their fingernails to pick but also use instruments such as tweezers, nail files and
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knives which often results in damage on the skin (Arnold et al. 1998; Odlaug & Grant, 2008;
Keuthen et al., 2000; Wilhelm et al., 1999). SPD, like HPD, occur in the absence of
underlying dermatological or other medical conditions, like scabies or acne (APA, 2013).
Wilhelm et al. (1999) found that 39% of patients started to pick their skin when dealing with
acne in their teenage years, and developed SPD after the dermatological condition “was
cured”. Studies show that SPD patients have lower quality of life compared to controls
(Odlaug et al., 2010). They also report a range of psychosocial and medical complications
caused by the behavior, including skin damage and infections and in most severe cases
permanent disfigurement (Odlaug & Grant, 2008; Wilhelm et al., 1999).
The relatedness of HPD and SPD
There are striking similarities in phenomenology and symptom presentation of SPD
and HPD (Bohne, Keuthen, & Wilhelm, 2005; Lochner, Simeon, Niehaus, & Stein, 2002;
Odlaug & Grant, 2008b; Snorrason et al., 2012; Teng et al., 2002). Both disorders involve
removing parts of the body (i.e. hair or skin) with recurrent behavior. People with HPD often
pull hairs that are different from other hairs (e.g. coarse or gray) and people with SPD often
target certain type of skin imperfections. It seems that in both groups seeing or feeling these
preferred features triggers episodes (Arnold et al., 1998; Odlaug & Grant, 2008b). It is
common that many patients engage in pre- and post-picking/pulling behavior like stroke the
skin to look for imperfections to pick or running fingers through hair to find hair with certain
texture. Many manipulate the skin or the hair afterwards, chew on it or eat it (Snorrason &
Björgvinsson, 2012; Snorrason, Smari & Olafsson 2011; Wilhelm et al., 1999). Normally
HPD and SPD patients use their fingers to pick or pull and some also use implements (e.g.
tweezers) (Arnold et al., 1998; Christenson, McKenzie, & Mitchell, 1991; Snorrason, Smári,
& Ólafsson, 2011; Wilhelm et al., 1999). About 33% of SPD patients report dissociation, or
some kind of trance like stage, while picking skin and more than 20% of hair-pulling patients
report experiencing depersonalization while pulling hair (Snorrason, Smári, & Ólafsson,
2010; Wilhelm et al., 1999; du Tiot et al., 2001).
One way to examine how related these disorders are, is to look at comorbidity.
Snorrason et al. (2012) reviewed the literature and found out that the prevalence of SPD in
HPD outpatient samples was on average 29.8% across studies and the prevalence of HPD in
SPD outpatient samples was on average 15.5% across studies. Lifetime prevalence of HPD in
inpatients samples is estimated to range from 1.3 to 4.4% (average 2.7% across studies)
(Grant, Levine, Kim, & Potenza, 2005; Müller et al., 2011; Tamam, Zengin, Karakus, &
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Ozturk, 2008) and lifetime prevalence of inpatients with SPD is estimated to range from 7.3
to 11.8% (average 9,6% across studies) (Grant, Williams, & Potenza, 2007; Müller et al.,
2011). By chance, the prevalence of co-occurrence of SPD and HPD in inpatients setting
should be around 0.26% (9.6 x 2.7 = 0.26) (Snorrason et al., 2012). Thus, the overlap
between these two conditions suggests that they may be closely connected.
It also seems that both disorders have shared genetic risk factors. In an internet survey
study, 50.8% of 718 participants, that met criteria for SPD, reported having a first-degree
relative with problematic skin picking and about 8% said they had a first-degree relative with
a history of an HPD diagnosis (Snorrason et al., 2015). Novak, Keuthen, Stewart and Pauls
(2009) investigated concordance rates for HPD in a twin study with both monozygotic (MZ)
and dizygotic (DZ) twins and found out that concordance rate for MZ twins (38.1%) was far
greater than the concordance rates of DZ twins (0%) which suggests a significant genetic
component for HPD. Another twin study showed that genetic factors accounted for
approximately 40% of the variance of skin picking (Monzani et al., 2012). Monzani et al.,
(2014) examined the degree to which genetic and environmental risk factors are unique
and/or shared by OCD and related disorders (body dysmorphic disorder, hoarding disorder,
HPD and SPD). The results showed two latent factors that were substantially heritable. One
of those two latent factors loaded exclusively on HPD and SPD and all the heritability
variance was shared by the two disorders The authors suggest that SPD and HPD might
represent alternative phenotypic expressions of the same genetic condition.. In a large OCD
family study it was discovered that both SPD and HPD, but not OCD, were associated with
variants in the human Sapap3 gene further supporting the notion that SPD and HPD may
have a common genetic association (Bienvenu et al., 2009). In summary, there is strong
evidence for relatedness between SPD and HPD, including possible shared genetic risk
factors, comorbidity, and similar clinical features.
Treatments for HPD and SPD
Cognitive-behavioral interventions for SPD and HPD (and other BFRB) can be
divided into two categories. The first category includes techniques directly aimed at
preventing or stopping picking and/or pulling behavior. These techniques include habit
reversal training and stimulus control. The second category includes strategies that are aimed
at managing internal states and other possible maintaining factors, such as dialectical
behavior therapy (DBT), acceptance and commitment therapy (ACT), and cognitive therapy
(CT)) (Snorrason & Woods, 2014).
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Habit Reversal Training (HRT). The first step in HRT is teaching the client to
become more aware of picking or pulling behaviors and preceding “warning signs”
including, urges or emotional changes, and movements early in the behavioral chain leading
up to pulling/picking (e.g., moving hand toward the scalp). The awareness training starts with
a careful functional assessment interview, were information about what happens before,
during, and after picking and/or pulling behavior are gathered. The patient is also asked to
engage in self-monitoring between sessions to further enhance his awareness of the behavior
and its context (Miltenberger, 2001). When the client has improved his awareness she is
taught to perform a physically incompatible behavior – called competing response (e.g.
sitting on one‘s hands) – whenever a warning signs or pulling/picking behaviors are detected
(Capriotti, Ely, Snorrason, & Woods, 2015; Snorrason, Berlin, Lee, 2015).
HRT is the treatment for HPD and SPD with the most empirical support (Azrin,
Nunn, & Frantz-Renshaw, 1982; Bloch et al., 2007; Franklin et al., 2011; Ghanizadeh, 2011;
Moritz, Treszl, & Rufer, 2011; Tucker, Woods, Flessner, Franklin, & Franklin, 2011) and
results show that HRT is an effective intervention for maladaptive repetitive behaviors like
HPD and SPD. Teng et al. (2006) compared HRT for SPD to a wait-list control group and
HRT was found to be more effective than the wait-list control condition and gains were
maintained at a 3 month follow-up. In addition, a meta-analysis (Bate, Malouff,
Thorsteinsson and Bhullar, 2011) based on 18 studies of HRT for a range of BFRBs showed
large effect size pre-treatment to post-treatment with d = 0.80.
Stimulus control (SC). HRT is often implemented in combination with stimulus
control (SC) interventions (Mansueto, Golomb, Thomas, & Stemberger, 2000). The goals of
SC is to make picking/pulling more burdensome or less reinforcing by identifying ways to
reduce picking/pulling opportunities in the client‘s environment. Examples of SC
interventions include removing/discard picking/pulling tools (e.g. tweezers), wear gloves,
cutting fingernails short to reduce the effectiveness of fingernails used for picking/pulling,
remove objects that facilitate picking/pulling (e.g. remove or cover bathroom mirror),
eliminate postural triggers (e.g. studying at a different desk) and restrict time in high-risk
situations (e.g. reduce time in front of mirror) (Mansueto et al., 1999). As listed above, HRT
has shown to be an efficacious intervention for both HPD and SPD. Bate et al. (2011) showed
that combined with SC it can reduce symptoms for 50-60% of individuals with HPD. Other
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randomized controlled trials have also demonstrated similar effect for SPD (Schuck, Keijsers,
& Rinck, 2011; Teng, Woods, & Twohig, 2006). To the best of our knowledge, no study has
examined the effect of SC as a monotherapy for SPD or HPD.
Cue-exposure/response prevention (CERP). In exposure and response prevention
patients are exposed to anxiety-provoking stimuli or cues that trigger urges or longing while
abstaining from performing anxiety- or urge reducing compulsions (e.g. reassurance and
avoidance) (Sulkowski, Jacob, & Storch, 2103). Originally exposure treatment was developed
to treat fear and phobias and has proven to be effective treatment for disorders like OCD,
BDD, post-traumatic stress disorder (PTSD), and panic disorder (e.g. Javidi, Battersby, &
Forbes, 2007; Sulkowski et al, 2013). For the last thirty years or so, exposure-based
treatments, like CERP, have also been used to help patients with disorders that involve urges
and cravings, including alcohol and substance use, over-eating and gambling (Conklin &
Tiffany, 2002; Havemans & Jansen, 2003; Jansen, 1998). The main difference between
exposure treatment for fear and anxiety and for urges or addiction is that instead of exposing
individuals to anxiety provoking stimuli, they are exposed to internal or external cues that
trigger urges to engage in the addictive behavior (Boutelle & Bouton, 2015).
HPD and SPD are often conceptualized as behavioral addiction (Shusterman, Feld,
Baer, & Keuthen, 2009; Snorrason, Smari & Olafsson, 2010) and brain imaging research
indicates that individuals with HPD/SPD show abnormalities in reward circuitry that has
previously been linked to craving and addiction (Roos, Grant, Fouche, Stein, & Lochner,
2015; White et al., 2013). Studies have shown that individuals with SPD and HPD experience
strong craving for picking/pulling and also gratification and pleasure while doing so (e.g.
Snorrason et al., 2010; Diefenbach, Tolin, Meunier, & Worhunsky, 2008). According to
behavioral model of SPD and HPD picking and pulling behavior is, just like addiction,
maintained by reinforcing consequences (Mansueto et al., 2000). The pleasurable experience,
such as gratification or relief that sometimes is produced by picking and/or pulling works as a
positive automatic reinforcement. At other times, the behavior can work as a negative
automatic reinforcement if it down-regulates negative experiences such as anxiety or
boredom (Snorrason et al., 2012). The picking and/or pulling behavior (US) produces
desirable affective reaction (UR) within the individual. If the behavior is repeated, a neutral
contextual cues (NS) can be paired with the US and acquire the ability to trigger urges (CR)
to perform the behavior through classical conditioning.
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If pulling and picking are instrumental responses that are influenced by classical
conditional cues, extinction theory can provide a useful framework to develop effective
treatments for BFRB like HPD and SPD by exposing the patient to triggering stimuli and
encourage him to experience the longing or urge to pick/pull without doing so. The object is
to extinguish the association between the conditioned cues and the behavior.
The rationale behind applying cue-exposure as a treatment for addictive behaviors is
therefore mostly based on classical conditioning models. Classical conditioning is the process
where an organism associates conditioned stimuli (CS) with a biologically meaningful event
(reinforcer), called unconditioned stimulus (US) (Woods & Ramsey, 2000). For example, in
HPD, the hair pulling is the unconditioned stimulus (US) and the desirable affective reaction
produced by the pulling is the unconditioned response (UR). The conditioned stimuli (CS) are
some contextual features (e.g. experiencing boredom/anxiety, or being alone in bedroom),
and those contextual features will evoke urges (CR) to pull and trigger hair pulling. Urges in
turn make the behavior more likely to occur. CERP is, in other words, based on behavioral
model of addictive behaviors.
Not much is known about the effect of CERP for SPD and HPD but at least two case
studies have been reported. Javidi et al. (2007) applied a cognitive-behavioral therapy
protocol, mostly based on CERP, in a treatment of a woman with HPD. The results were
impressive, with visible progress after only four treatment sessions, and gains had been
maintained at 4 years follow-up. Later, a CERP treatment was applied on an adolescent girl
with HPD and comorbid OCD and resulted in a significant reduction in pulling behavior
(Sulkowski, Jacob, & Storch, 2013). Cue exposure has also been used on patients with HPD
and SPD as a component in ACT therapy and showed promising results (Capriotti et al.,
2015; Snorrason & Woods, 2014; Twohig, & Woods, 2004). In ACT, the client is taught to
accept internal states (e.g. urges) without trying to control them or react out in anyway
(Snorrason & Woods, 2014). This is accomplished with variety of experiential exercise were
the aim is to weaken aversive internal stimuli, and break the discriminative control of urges
and negative affect over overt behavior (Capriotti et al., 2015).
Purpose of the present study
The aim of the present study is to examine the efficacy of HRT-CERP for HPD/SPD
by comparing it to HRT-SC, which is a first-line treatment for these conditions. Previous
studies have shown that HRT-SC consistently results in significant reduction in symptoms
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from pre to post treatment. However, relapse rates are high after recovery (Capriotti et al.,
2015; Rhem, Moulding, Nedeljkovic, 2015; Snorrason et al., 2015). The goal of SC is to
reduce picking and/or pulling opportunities in the environment. Unfortunately, SC may at the
same time reduce the number of extinction trials that the patients can practice the competing
response in high-risk situations. Therefore, it is possible that SC interventions can
compromise the long-term outcome of HRT. Some researchers have also suggested that
internal events like urges, impulses, and aversive affects may play important role in
promoting relapse. possibly be more effective in treating these problems (Keuthen et al.,
2011; Woods, Wetterneck, & Flessner, 2006) but those internal events are not treated directly
in HRT-SC. However, in HRT-CERP, the numbers of extinction trials will increase and
internal events are also treated. Thus, in this randomized controlled clinical trial, HRT-CERP
was compared to HRT-SC. Twenty university students diagnosed with either HPD or SPD
were randomized to receive either HRT-SC or HRT-CERP. It was hypothesized that HRT-
CERP would show similar effect as HRT-SC at post-assessment (hypothesis 1). It was also
hypothesized that the relapse rate would be lower for HRT-CERP at the one-month follow-
up, but the results of the follow-up will not be discussed in this essay.
The design of the study also allowed to explore mechanisms of change -if cue-
reactivity would decrease from pre to post treatment and if the magnitude of the decrease
would differ between treatment conditions. It was expected that cue-reactivity would
decrease from pre- to post treatment (hypothesis 2). It was also expected that this reduction
would be greater in HRT-CERP because it explicitly targets high-risk situations and
encourages clients to experience strong urges without picking that may extinguish negative or
positive reinforcement contingencies in HPD and SPD (hypothesis 3).
16
Method
Participants
Participants were recruited by sending an invitation via email to all students registered
at the University of Iceland (N≈10.000). Subsequently, the participants who responded to the
email were contacted and a phone screening was performed. Total of 124 individuals (82%
female) responded to the recruitment email and underwent phone screening to determine
eligibility. Eligible participants were then invited to an assessment interview which also
included more thorough screening. Inclusion and exclusion criteria can be seen in Table 1.
After phone screening, 24 (23 female) participants were invited to the pre-assessment
interview that was also used as a more thorough screening. Four participants were excluded
because they did not meet the inclusionary or the exclusionary criteria. The participant flow
can be seen on the consort diagram in Figure 1. As displayed in the consort diagram, 20
participants diagnosed with either SPD (n=15) or HPD (n=5), enrolled into randomization.
Enrolled participants were all female and the mean age was 26.5 years (SD=5.4).
Table 1
Inclusion / exclusion criteria
Inclusion criteria
a. A primary DSM-5 diagnosis of SPD or HPD
b. Not currently receiving psychotherapy for SPD or HPD
c. Participant could be on psychotropic medications, but must agree not to alter the dosage
of the medication, or start new medication, during the course of treatment
d. Committed to a 4 week treatment
e. Willing to be randomized
Exclusionary criteria
a. A lifetime diagnosis of Bipolar I Disorder, Psychotic Disorder, Autism spectrum
disorders
b. Current major depressive episode, severe
c. Current diagnosis of substance use disorder (except nicotine dependence)
d. Current suicidal risk
17
Measures
Phone screen. The phone screening consisted of a 16-item interview form
constructed by the researchers, with question regarding HP/SP behavior, current DSM-5
diagnostic criteria for SPD and HPD, and inclusion/exclusion criteria.
Psychiatric interviews.
The Mini International Neuropsychiatric Interview. (MINI; Sheehan et al., 1997) is
a semi structured diagnostic interview that screens for the most common mental disorders of
the DSM-IV (APA, 2000). The interview has good psychometric properties and high
correlation with longer and more comprehensive diagnostic interviews (Lecrubier et al, 1997;
Sheehan et al., 1997). The Icelandic version, translated by Pétur Tyrfingsson, has
psychometric properties that are comparable to the original version (Sigurðsson, 2008). The
present study employed a composite version of the MINI and the Body Dysmorphic Disorder
(BDD) module of MINI-plus with additional questions.
Clinical Global impression (CGI) Scale. This is a semi-structured interview that
assesses overall impairment and treatment response. The interview has two items, a 7 point
Figure 1. Consolidated Standards of Reporting Trials (CONSORT) diagram of participants flow.
18
impairment scale and a 7 point improvement scale. This interview is considered by many as
the gold standard in research on effectiveness of psychological and pharmacological
treatments of psychiatric problems (Bushner & Targum, 2007; Guy & Bonato, 1970).
Problematic Habit Interview Schedule (PHIS). This is a semi-structured interview
designed to assess the DSM-5 diagnoses and clinical characteristics of HPD and SPD. The
interview assesses both current and past skin-picking/hair-pulling habits, and whether current
HP/SP behavior meets DSM-5 criteria for HPD or SPD. In particular, the interview examines
whether HP/SP results in (1) skin lesion/hair-loss, (2) emotional distress, (3) impairment in
functioning, (4) desire to stop or reduce behavior, and (5) previous attempts to stop or reduce
behavior. The interview also assesses if behavior is solely due to a medical condition,
substances or another psychiatric disorder (Snorrason, Belleau, & Lee, unpublished). The
interview was translated to Icelandic by Ívar Snorrason.
Skin Picking Scale-Revised Interview Version (SPS-R-IV). This is an interview
version of the SPS-R self-report scale that is described below.
MGH Hair Pulling Scale Interview Version (MGH-HPS-IV). This is an interview
version of the MGH-HP self-report scale that is described below.
Prior treatment history interview. Information about prior treatment history was
gathered in the pre-assessment interview. Participants were asked if they had mentioned the
disorder, or sought treatment, from a healthcare professional (e.g. psychiatrist or
psychologist). If so they were asked about what kind of intervention or reaction they
received. The interview was designed by the research group to evaluate the knowledge and
treatment on HPD/SPD by healthcare professionals in Iceland.
Self-Report Measures for SPD.
Skin Picking Scale-Revised (SPS-R). SPS-R is an 8 item self-report scale that was
designed to measure the severity of skin-picking during the past week. It has two subscales;
Symptom severity that consists of items assessing frequency and intensity of urges, time
spent picking and control over the skin-picking behavior. The other subscale is Impairment
that consists of items assessing emotion distress, functional impairment, skin damage and
social avoidance. All the items are rated on a 5 point scale that ranges from 0 (none) to 4
(extreme). The scale was translated to Icelandic by Ívar Snorrason. The scale has good
psychometric properties (Snorrason et al., 2012).
Milwaukee Inventory for Dimensions of Adult Skin Picking (MIDAS). MIDAS is a
12-item self-report scale that is designed to measure focused and automatic style of skin-
19
picking. Each subscale consists of 6 items. Focused skin-picking is when behavior is done
with full awareness in response to urges or negative affective states. Automatic style is
characterized by picking without reflective awareness. All items are rated on a 5 point scale
ranging from 1 (not true for any of my picking) to 5 (true for all my picking). The scale was
translated to Icelandic by Ívar Snorrason. Walther, Flessner, Conelea, and Woods (2009)
demonstrated acceptable psychometric properties of both scales.
Skin Picking Reward Scale (SPRS). SPRS is a 12-item scale that is designed to
assess how much an individual wants and likes to pick skin. It has two subscales; wanting
(motivational drive to engage in picking) that consists of 6 items and liking (pleasurable
experience during picking) that also consists of 6 items. The items are rated on a scale from 1
(almost never) to 4 (almost always). The scale was translated to Icelandic by Ívar Snorrason.
Snorrason, Ólafsson, Houghton, Woods, and Lee (2015) showed that the psychometric
properties of the scale are good.
Self-Report Measures for HPD.
Massachusetts General Hospital Hair pulling Scale (MGH-HS). MGH-HS is a
seven-item self-report scale that measures urge frequency, intensity, and controllability. It
also measures hair pulling frequency, resistance, and controllability, and associated distress
during the prior week. All items are rated on a 5-point scale with ratings from 0 to 4. The
total score ranges from 0-28, with higher score indicating greater severity. The scale was
translated to Icelandic by Ívar Snorrason. The scale has excellent test-retest reliability and
good convergent and divergent validity (Diefenbach, Tolin, Crocetto, Maltby, & Hannan,
2005; Keuthen et al., 1995).
Milwaukee Inventory for Subtypes of Trichotillomania-Adult Version (MIST-A).
MIST-A is a 15 item self-report scale that measures focused and automatic pulling. The
focused pulling scale has ten items and the automatic scale has five items. The items are rated
from 0 to 9 with focused scale score ranging from 0-90 and automatic scale score from 0-45.
According to Flessner et al. (2008) the scale has a satisfactory internal consistency and good
convergent and divergent validity. The scale was translated to Icelandic by Ívar Snorrason.
Hair Pulling Reward Scale (HPRS). HPRS is designed to assess how much an
individual wants (motivational drive to engage in pulling) and likes (pleasurable experience
during pulling) to pull hair. This scale is identical to the Skin Picking Reward Scale, the only
difference being that this scale assesses how much the individual wants and likes hair-pulling,
not skin-picking. The scale was translated to Icelandic by Ívar Snorrason. The self-report
20
scale is a 12-item scale. It has two subscales, wanting and liking that both consists of 6 items.
The items are rated on a scale from 1 (almost never) to 4 (almost always) and a previous
study has shown that it has good psychometric properties (Snorrason et al., unpublished).
Other self-report measures.
Depression Anxiety and Stress Scale 21-item version (DASS-21). The DASS-21 is a
21-item questionnaire designed to measure symptoms of depression, anxiety, and stress in
both clinical and non-clinical populations. Each domain contains seven items in which the
respondent has to indicate the extent to which a statement applies to him using a 4-point
Likert scale. Studies show that all three scales have good psychometric properties (Anthony,
Bieling, Cox, Enns, & Swinson, 1998). The Icelandic version was translated by Pétur
Tyrfingsson and the translated version shows good psychometric properties, good convergent
and divergent validity on depression and anxiety scales but results are unclear for the stress
scale (Ingimarsson, 2010).
Not Just Right Experiences-Questionnaire-Revised (NJRE-Q-R). The NJRE-Q-R is
a 19-item questionnaire that is designed to assess a general tendency for not just right
experiences. In the beginning there is a list of 10 common NJRE and the respondent is asked
to indicate whether or not they have experienced them in the past month. The sum of these
items yields NJRE-Q-R variety score. The respondent is asked to select the most recent NJRE
and rate it on seven severity items. The sum of these items yields NJRE-Q-R- Severity score
(Coles, Frost, Heimberg, & Rheaume, 2003). The scale was translated to Icelandic by Ragnar
P. Ólafsson but psychometric properties are unclear in the Icelandic version.
Intolerance of Uncertainty (IUS). The IUS is a 27-item self-questionnaire that is
used to measure participants level of uncertainty of intolerance. In this scale uncertainty is
being perceived as a stressful and upsetting phenomena, uncertainty leading to the inability to
act, or uncertain events being perceived as negative and should be avoided. The respondent is
asked to rate items on a 5-point Likert scale range from 1 (“not at all characteristic of me“)
to 5 (“entirely characteristic of me“) (Freeston, Rhéaume, Letarte, Dugas, & Ladocuer,
1994). The IUS has been shown to have excellent internal consistency and good test-retest
reliability over a 5 week period (Buhr & Dugas, 2002). The Icelandic version was translated
by Ragnar P. Ólafsson.
Paper/pencil cue reactivity test. In this simple cue-reactivity test, responders are
presented with a written instruction and asked to imagine pulling/picking at the present
moment. Then they are asked to answer two questions; 1) How pleasurable would it be to
21
pick skin/pull hair at this moment? 2) How much gratification would you experience if you
picked skin/pulled hair right at this moment? Both items are rated on a 0-10 scale with ends
labeled not at all pleasant to extremely pleasant. Both items are administered twice – before
and after the administration of self-questionnaires about positive aspects of skin picking/hair
pulling. The greater before-after increases in the pleasure/gratification ratings suggest greater
cue-reactivity (Snorrason et al., 2015).
Satisfaction questionnaire. Participant’s satisfaction and opinion about the treatment
and treatment factors were evaluated on a 14-item self-report questionnaire, divided into 4
subscales. The first subscale measured how much the client’s knowledge on SPD/HPD had
increased after treatment. Second subscale measured how useful the client evaluated different
treatment factors. The third subscale assessed the likelihood of certain treatment factors to be
used if relapse would occur. The last subscale evaluated the similarity between this treatment
protocol and prior treatment. Only participants with prior treatment history answered the last
subscale. All items are rated on a 5-point scale with ratings of 1 to 5, the higher the score the
higher was the satisfaction and positive opinion.
Picture ratings. Pictures of hair loss or skin damage were taken pre and post
treatment. Independent evaluators, blind to the purpose of the study, will be asked to rate the
severity of the hair loss/skin damage for each photo. Average score of each subject, across
raters, will be compared from pre and post treatment. The pictures will not be used to
evaluate treatment progress in this essay.
Procedure
The study was approved by the Icelandic data protection authority and the National
Bioethics Committee. All the students who answered the email invitation went through a
brief phone screening. Participants deemed eligible during phone screening were invited to a
baseline assessment that included more thorough screening. After signing an informed
consent and answering general background information that consisted of question about
participant’s age, gender, marital status and their educational level, participants completed a
package of self-report questionnaires (described above). The package included the following
self-report questionnaires: general background information; paper/pencil cue reactivity test
package; SPS-R/MGH-HS; DASS-21; IUS; NJRE-QR. After completing the self-report
questionnaires, participants underwent a psychiatric interview that included interview about
prior treatment history, PHIS, SPS-R-IV or MGH-HS-IV, CGI, and MINI. At the end of the
baseline assessment pictures were taken of picking/pulling locations on each participant.
22
Eligible participants were randomized to either treatment condition. The randomization into
treatment groups was issued by an individual independent from the study itself. The primary
diagnosis of HPD and SPD was used as a variable block in the randomization into treatment
groups so the ordering was as equal as possible with two individuals with HPD in HRT-SC
and three individuals with HPD in HRT-CERP. First treatment session was scheduled within
seven days from the baseline session.
Treatments. The treatment for both groups consisted of HRT that included self-
monitoring, awareness training, competing response, and relapse prevention methods. Both
treatment groups also got psychoeducation and motivational enhancement alongside with
HRT. The difference between the groups was that ten participants got HRT implemented with
CERP and ten participants got HRT implemented with SC. Both treatment protocols were
developed by Snorrason and Ólafsson (unpublished), and adapted from existing protocols.
The treatment packages consisted of four 1-hour individual sessions that were conducted
weekly. In table 2 is an overview of session by session of both treatment forms.
Table 2
Session by session overview of both treatments
HRT-SC HRT-CERP
Session#1
Psychoeducation; treatment rationale
Functional assessment
Motivational enhancement
Homework assignment: self-monitoring;
psychoeducation; motivational assignment
Psychoeducation; treatment rationale
Functional assessment
Motivational enhancement
Homework assignment: Self-monitoring;
psychoeducation; motivational assignment
Session#2
Review homework
Awareness training
Assign competing response (CR)
Develop stimulus control (SC) intervention
Homework assignment: self-monitoring; CR; SC
intervention
Review homework
Awareness training
Fill out exposure hierarchy
Assign competing response (CR)
In-session cue exposure
Post-exposure processing
Homework assignment: self-monitoring; cue
exposure; CR
Session#3
Review homework
SC intervention
CR problem-solving
Homework assignment: self-monitoring; CR; SC
intervention
Review homework
CR problem-solving
In-session cue exposure
Post-exposure processing
Homework assignment: self-monitoring; cue-
exposure; CR
Session#4
Review homework
SC intervention
CR problem-solving
Relapse prevention
Review homework
CR problem-solving
In-session cue exposure
Post-exposure processing
Relapse prevention
23
HRT and other shared treatment factors. The psychoeducation was the same for both
treatment groups except for the treatment rationale. The goal of the education was to provide
general information on the disorder and the treatment. All participants were provided with a
psychoeducational handout and encouraged to read further educational material on their own.
Two exercises were used in motivational enhancement. In session the client was
asked to list costs and benefits associated with continuing pulling/picking, and stop
pulling/picking. Then the costs and benefits of either option were evaluated. For homework
after first session the participants got either inconvenience review or the magic wand thought
experiment. In the inconvenience review the client was asked to list negative consequences of
HP/SP that covers different life domains. In the magic wand thought experiment the client
was asked to imagine and write down how their life would be different if the habit would
disappear.
Considering that the behavioral model of HPD/SPD assumes that the behavior is
maintained by reinforcing consequences the functional assessment consisted of questions that
assessed (1) antecedents of hair pulling (e.g. cues that evoke urges, discriminative stimuli that
signals upcoming HP/SP reward), (2) detailed description of HP/SP episode and (3) negative
and positive consequences of HP/SP.
One of the main elements in HRT is awareness training. The following three activities
were used to increase the client’s awareness of the behavior. (1) Through functional
assessment interview, (2) with self-monitoring which can also provide valuable information
about high-risk situations and (3) with in-session exercises. During a casual conversation
with the client the therapist performed a warning sign and the client had to indicate when he
identified the sign. Then the roles were reversed.
When the client had become efficient with identifying warning signs she was
introduced to a competing response. The client was instructed to perform a competing
response every time she noticed a warning sign or found herself picking/pulling. The CR
should be performed for 1 minute or until the urge was gone. The client was also asked to
demonstrate the competing responses in session.
The relapse prevention was mainly a discussion about the difference between a lapse
and a relapse. The client was also helped to identify emotions, thoughts, and situations that
signals upcoming lapse or relapse and coping strategies were designed to deal with them.
The difference between the treatment groups. In cue-exposure exercises, the client
was asked to evoke the urge to pull/pick while at the same time do nothing to relief the urge
24
(i.e., not allowed to pull/pick or to engage in any distraction). In the beginning stages of
treatment exposure hierarchy was created with the client, based on information from the
functional assessment. Before every exercise clients beliefs and expectations were
documented to set up for potential expectancy violation.
The main focus of stimulus control is to figure out ways to change the client’s
environment so pulling/picking behavior becomes more effortful and/or less rewarding. All
stimulus control interventions were chosen in collaboration with the client and were selected
based on the information gathered from the functional assessment.
Phone follow-up
Approximately one month after last treatment session, participants received a phone
call from the therapists and the following measurements were used to assess the current
situation regarding HP/SP behavior; PHIS, SPS-R-IV/MGH-HP-IV and CGI. The results of
the 1-month phone follow up will not be discussed in this essay.
Therapists
The treatments were delivered by two therapists who were master’s-level students in
clinical psychology at the University of Iceland. Both therapists were carefully trained to
deliver both treatments. Supervision- and consult meetings were held at least weekly over the
course of treatment. Every treatment session was audio-recorded and random session listened
to by supervisors.
Statistical Analysis
The statistical program IBM SPSS statistic data editor version 20 was used for
processing of data. T-tests and Fisher’s exact tests were used for group comparisons at
baseline. A two-tailed (superiority) mixed ANOVAs, with treatment groups as between-
subjects factor and time of assessment (pre vs. post treatment) as the within-subjects factor,
were used to test for changes during treatment and in interaction with type of treatment.
Cohen‘s d effect sizes were calculated from mean difference between the groups that
was divide by the pooled standard deviation of the means. Cohen (1988) suggests that
d=0.2 should be considered a 'small' effect, 0.5 a 'medium' effect and 0.8 a 'large' effect size.
Because the self-report questionnaires SPS-R and MGH-HS contained eight and
seven items each, average scores were constructed by dividing the total score with number of
25
items in each questionnaire. The resulting average score is on a scale from 0 to 4 (i.e. the
response scale).
The total missing value count was six data points on four different self-report
questionnaires. Due to the fact that the frequency of missing values was low, every missing
value was replaced with the most frequent response choice on that questionnaire (or scale) for
each participant.
26
Results
Pre-treatment Comparisons
Demographic and clinical characteristics. Descriptive statistics for demographic
and clinical variables for both groups are presented in Table 3. All participants were female
and mean age was similar across groups. All participants were university students so the
educational level was similar.
The background of participants was generally similar across groups. Number of
comorbid psychiatric problem was similar in both groups but four participants had current
diagnosis of MDD in HRT-SC group against two participants in HRT-CERP.
Table 3
Demographic information by condition
Variable
HRT-SC
(n=10)
HRT-CERP
(n=10) Test statistics p
Age mean (SD) 25.2 (2.2) 27.5 (7.3) 6.52a 0.36
Marital status n
3.33b 0.17
Single 8 4
Married or cohabiting 2 6
Educational level n
0.95b 0.63
Studying for a bachelor degree 7 6
Finished bachelor degree 3 4
Primary diagnosis n
0.27b 1.0
HPD 2 3
SPD 8 7
Automatic or focused behavior n 1.82b 0.37
Automatic 4 7
Focused 6 3
Comorbid disorders according to MINI n 0.20b 1.0
one disorder 2 3
two or more 3 2
…of those with MDD 4 2 0.95b 0.63
Note: SD=Standard deviation. HRT-SC=Habit Reversal Training – Stimulus Control; HRT-CERP=Habit Reversal Training
– Cue Exposure with Response Prevention; HPD=Hair-Pulling Disorder; SPD=Skin-Picking Disorder; MDD=Major
Depressive Disorder. a Independent samples t-test bFisher’s Exact Test - with 2 tailed significance
27
Depression, anxiety, and stress (DASS-21). Table 4 shows baseline severity of
anxiety, depression and stress for both treatment groups. There was no significant difference
in the total DASS-21 score between HRT-SC and HRT-CERP conditions before treatment;
t(18)=0.22, p=0,828, and no significant differences emerged on the subscale level of the
DASS either (p >0.10 in all cases).
Symptom severity. Table 4 displays the scaled mean scores of SPS-R / MGH-HS,
SPS-R-IV / MGH-HS-IV, and CGI at baseline for both groups. There were no group
differences on SPS-R/MGH-HS; t(18)=0.153, p=0.880, SPS-R-IV/MHG-HS-IV;
t(18)=0.522, p=0.608 or CGI severity scale t(18)=0.399, p=0.695 before treatment.
Table 4
Mean scores for measures of symptom severity pre- and post-treatment and effect sizes for both
treatment groups (n=10 in both treatment groups).
Pre-treatment Post-treatment
Measurements M (SD) M (SD) Cohen‘s d
DASS-21
Anxiety
HRT-SC 7.60 (8.47) 4.60 (4.10) 0.45
HRT-CERP 6.40 (6.45) 4.20 (5.20) 0.38
Both groups 7.00 (7.36) 4.40 (4.57) 0.42
Depression
HRT-SC 16.40 (13.56) 10.60 (11.5) 0.46
HRT-CERP 12.20 (9.91) 5.80 (6.5) 0.76
Both groups 14.30 (11.74) 8,20 (9.45) 0.57
Stress
HRT-SC 14.00 (8.74) 9.20 (4.0) 0.71
HRT-CERP 17.00 (9.13) 12.00 (9.97) 0.52
Both groups 15.50 (9.13) 10.60 (7.54) 0.59
Total score
HRT-SC 38.00 (26.0) 24.40 (16.1) 0.63
HRT-CERP 35.60 (22.5) 22.00 (20.9) 0.63
Both groups 36.80 (23.74) 23.20 (18.24) 0.64
HPD/SPD symptom severity
Self-reports (SPS-R/MGH-HS)1
HRT-SC 2.20 (0.55) 1.40 (0.64) 1.30
HRT-CERP 2.19 (0.47) 0.90 (0.51) 2.50
Both groups 2.21 (0.51) 1.19 (0.62) 1.80
Interview versions(SPS-R-IV/MGH-
HS-IV)1
HRT-SC 2.24 (0.42) 1.45 (0.75) 1.29
HRT-CERP 2.14 (0.44) 0.81 (0.45) 2.96
Both groups 2.19 (0.43) 1.13 (0.69) 1.72
CGI-Severity
HRT-SC 4.50 (1.18) 2.80 (1.47) 1.28
HRT-CERP 4.30 (1.06) 1.80 (1.14) 2.27
Both groups 4.40 (1.10) 2.30 (1.38) 1.68 Note: M=mean; SD=standard deviation; DASS-21=Depression Anxiety Stress Scale-21item; SPS-R=Skin Picking Scale-Revised; MGH-HS=Massachusetts General Hospital-Hair-pulling Scale; SPS-R-IV=Skin Picking Scale-Revised-Interview Version; MGH-HS-
IV=Massachusetts General Hospital-Hair-pulling Scale-Interview Version; CGI= Clinical Global Scale; HRT-SC=Habit Reversal Training
– Stimulus Control; HRT-CERP=Habit Reversal Training – Cue Exposure with Response Prevention. 1Scaled mean score because of different item count on each list. In appendix I is a table that displays total scores from self-report and
interview version for each participant.
28
Treatment Efficacy
Correlation between primary outcome measures. The correlation between
SPSR/MGH-HS, SPS-R-IV/MGH-HS-IV, and CGI-severity scale at pre and post treatment is
shown in Table 5. There was a significant relationship between SPS-R/MGH-HS and SPS-R-
IV/MGH-HS-IV in the pre-assessment. There was also a significant relationship between
SPS-R/MGH-HS and SPS-R-IV/MGH-HS-IV post-assessment. This strong correlation
indicates that there was convergence between ratings of symptom severity between
participants and therapists, at both pre and post treatment.
SPS-R/MGH-HS self-report scales. A 2(time: pre- vs. post-assessment) x
2(treatment group; HRT-SC vs. HRT-CERP) mixed design ANOVA was conducted. There
was a significant main effect for SPS-R/MGH-HPS across the two time points,
F(1,18)=45.95, p<0.001. No significant main effect of group was found, F(1,18)=1.945,
p=0.180, nor an interaction between time and group, F(1,18)=2.50, p=0.131. Effect size was
calculated to gain further insight into clinical significance of the improvement achieved in the
two conditions as displayed in Table 4.
SPS-R-IV/MGH-HS-IV interview. A 2(time: SPS-R-IV/MGH-HS-IV; pre- vs. post-
assessment) x 2(treatment group; HRT-SC vs. HRT-CERP) mixed design ANOVA was
conducted. There was a significant main effect for HP and SP severity across the two time
Table 5
Correlations between self-administered and interview based assessment of symptom severity at pre
and post treatment
1 2 3 4 5 6
1. SPS-R/MGH-HS pre treatment ―
2. SPS-R-IV/MGH-HS-IV pre
treatment
.841** ―
3. CGI-severity scale pre
treatment
.040 .145 ―
4. SPS-R/MGH-HS post
treatment
.252 .511* .153 ―
5. SPS-R-IV/MGH-HS-IV post
treatment
.268 .510* .315 .934** ―
6. CGI-severity scale post
treatment
-.068 .167 .439 .807** .822** ―
Notes: SPS-R=Skin Picking Scale-Revised; MGH-HS=Massachusetts General Hospital-Hair-pulling Scale; SPS-R-IV=Skin Picking
Scale-Revised-Interview Version; MGH-HS-IV=Massachusetts General Hospital-Hair-pulling Scale-Interview Version; CGI= Clinical
Global Scale *p<0.05, **p<0.01
29
points, F(1,18)=75.74, p<0.001. There was also a significant interaction between time and
group, F(1,18)=4.798, p=0.042. No significant main effect of group was found,
F(1,18)=3.169, p=0.092. This indicates that there was no significant difference between the
groups at pre-assessment however the mean scores from SPS-R-IV/MGH-HS-IV are
significantly lower for HRT-CERP compared to HRT-SC at post-assessment.
Effect size was calculated to gain further insight into clinical significance of the
improvement achieved in the two conditions as displayed in Table 4. The effect size for
HRT-SC measured on SPS-R-IV/MGH-HS-IV interview was 1.29 but 2.96 for the HRT-
CERP group.
CGI scores. A 2(time: CGI-Severity scale; pre- vs. post-assessment) x 2(treatment
group; HRT-SC vs. HRT-CERP) mixed designed ANOVA was conducted. There was a
significant main effect for CGI severity across the two time points, F(1,18)=51.88, p<0.001.
No significant main effect of group was found, F(1,18)=1.68, p=0.211, or an interaction
between time and group, F(1,18)=1.88, p=0.187. This indicates that both treatments have
significant effect on CGI severity score but the effect did not differ between groups.
Effect size was calculated to gain further insight into clinical significance of the
improvement achieved in the two conditions as displayed in Table 4. The effect size for
HRT-SC measured on CGI-severity scale was 1.28 but 2.27 for the HRT-CERP group.
The CGI-improvement scale showed that 40% of patients in HRT-SC were estimated
by researchers to be “much” or “very much” improved after treatment. 70% of participants in
HRT-CERP were estimated to be “much” or “very much” improved after treatment.
Session-by-session self-report mean scores. Table 6 displays the session-by-session
mean score of SPS-R/MGH-HS for both treatment groups over the course of treatment. The
mean score of those in HRT-CERP gradually decreased over time. In the HRT-SC the mean
score decreased throughout treatment but remained relatively stable from session#4 to post-
assessment.
Table 6
The scaled mean score of SPS-R/MGH-HS from pre assessment to post-assessment for both groups
Treatment groups Pre -
treatment
Session #1 Session #2 Session #3 Session #4 Post -
treatment
HRT-SC – Mean (SD) 2.23 (0.55) 1.98 (0,57) 1.76 (0.48) 1.53 (0.52) 1.41 (0.63) 1.45 (0.64)
HRT-CERP – Mean (SD) 2.19 (0.47) 2.12 (0.61) 1.68 (0.45) 1.43 (0.62) 1.07 (0.62) 0.94 (0.51)
30
Other outcomes
DASS-21. A 2(time: DASS-21 total score; pre- vs. post-assessment) x 2(treatment
group; HRT-SC vs. HRT-CERP) mixed design ANOVA was conducted. There was a
significant main effect for time, F(1,18)=9.616, p=0.006. No significant main effect of group
was found, F(1,18)=0.0, p=1.0, nor an interaction between time and group, F(1, 18)=0.077,
p=0.785. This means that significant reductions in DASS scores were observed following
treatments, that were not qualified by type of treatment. Effect sizes were moderate in size
(table 4).
Cue-reactivity. It was hypothesized that cue-reactivity would decrease from pre to
post treatment in the HRT-CERP. However, no significant changes were observed as a result
of the cue in the cue-reactivity test pre- or post treatment. This means that changes in cue-
reactivity as a result of the treatment could not be assessed.
SPRS/HPRS ‘Wanting’ and ‘Liking’ subscale scores. It was examined if the
change in the wanting and liking subscale from SPRS/HPRS correlated with the change in
SPS-R/MGH-HS and SPS-R-IV/MGH-HS-IV severity scores. As displayed in Table 7, the
correlation between the change in ‘wanting’ and the changes in severity of symptoms was
non-significant. The correlation between the change in ‘liking’ and the change in SPS-
R/MGH-HS scores was significant, r(18)=0.537, p=0.0145, and the change in liking and
SPS-R-IV/MGH-HS-IV was also significant, r(18)=0.500, p=0.025. This moderately strong
correlation suggests that changes in positive attitudes towards pulling/picking behavior and
changes in symptom severity are related.
Change in SPRS/HPRS ‘Wanting’ subscale score. A 2(time: ‘wanting’; pre- vs.
post-assessment) x 2(treatment group; HRT-SC vs. HRT-CERP) mixed design ANOVA was
conducted. There was a significant main effect for time, F(1,18)=11.35, p=0.03. No
significant main effect of group was found, F(1,18)=19.6, p=0.449, nor an interaction
between time and group, F(1,18)=0.196, p=0.663. This means that there was a significant
change in wanting scores following treatment that was not qualified by type of treatment.
Change in SPRS/HPRS ‘Liking’ subscale score. A 2(time: ‘liking’; pre- vs. post-
assessment) x 2(treatment group; HRT-SC vs. HRT-CERP) mixed design ANOVA was
conducted. No significant main effect of group was found, F(1,18)=3.23, p=0.736 but there
was a significant interaction between time and group, F(1,18)=4.50, p=0.048. No differences
were observed between the groups pre-treatment but mean scores from the ‘liking’ subscale
31
from SPRS/HPRS were significantly lower for HRT-CERP group compared to HRT-SC at
post-assessment.
Table 7
Correlation matrix of pre-post treatment difference from self-reports, interview versions, and
‘Liking’ and ‘Wanting’ subscales
1 2 3 4
1. SPS-R/MGH-HS pre-post difference ―
2. SPR-R-IV/MGH-HS-IV pre-post difference 0.849**
―
3. SPRS/HPRS ‘Liking’ subscale pre-post difference 0.537* 0.500
* ―
4. SPRS/HPRS ‘wanting’ pre-post difference 0.295 0.335 0.357 ―
Notes: SPS-R=Skin Picking Scale-Revised; MGH-HS=Massachusetts General Hospital-Hair-pulling Scale; SPS-R-IV=Skin Picking
Scale-Revised-Interview Version; MGH-HS-IV=Massachusetts General Hospital-Hair-pulling Scale-Interview Version; SPRS=Skin-
Picking Reward Scale; HPRS=Hair-Pulling Reward Scale *p<0.05, **p<0.01
32
Discussion
The primary aim of the present study was to examine the efficacy of HRT-CERP as a
treatment for HPD/SPD. A secondary aim of the study was to examine if cue-reactivity
would decrease from pre to post treatment and if this decrease would differ between the
HRT-CERP and HRT-SC.
The results showed that both HRT-CERP and HRT-SC significantly reduced
symptoms of HPD and SPD, according to all outcome measures, including self-report
questionnaires (SPS-R-IV/MGH-HS), the symptom severity interview (SPS-R-IV/MGH-HS-
IV) and general clinical impression (CGI). Comparison between the treatments suggested an
overall equal efficacy. In general, these results suggest HRT-CERP can beat least, equally as
efficacious as HRT-SC, which is an established first-line treatment for HPD and SPD. If
anything, the HRT-CERP may have been slightly superior to HRT-SC in the sample. In all
measurements assessing HPD/SPD symptom severity the effect size was larger for HRT-
CERP in comparison to HRT-SC. Moreover, HRT-CERP did show significantly greater
efficacy according to the symptom severity interview and CGI-Improvement. The reason for
the difference between interviews and self-report measures is unclear. One possibility is that
interviewer was able to identify clinically meaningful improvement in symptoms not reported
by the participants. However, the correlation between the self-report and the interview
versions was very high after treatment, which indicates that there was a similarity between
how the participants and interviewer rated the severity of symptoms. Further studies in larger
samples, with independent raters blind to treatment condition and study purpose, are needed
to confirm these results.
CERP vs SC in preventing relapse
HRT-SC is an empirically supported first-line treatment for HPD and SPD. However,
as noted in the introduction the relapse rate is relatively high after recovery in HRT-SC
(Capriotti et al., 2015; Rhem, Moulding, Nedeljkovic, 2015; Snorrason et al., 2015). It is
believed that HRT works in part by extinguish negative reinforcement contingency between
picking/pulling urges, picking/pulling behavior and subsequent reinforcing experiences
(Mansueto et al., 1999). In HRT, the patient is taught to engage in a competing response
every time an urge or other signals to pick or pull occurs. By doing so the patient undergoes
repeated naturalistic extinction trials. However, when HRT is implemented with SC, the goal
of SC is to reduce pulling/picking opportunities and avoid high-risk situations (Mansueto et
33
al, 1999). Therefore, SC can reduce the number of extinction trials for the patient to practice
in. Even though SC may be effective to reduce picking/pulling in the short-run, it may
enhance relapse rates by reducing the chances to practice in high-risk situations.
Instead of avoiding environmental factors or cues that provoke the urge to pull/pick,
in CERP the patient is encouraged to experience those urges without pulling or picking in
those difficult situations. With repeated exposure to those cues and triggers in the absence of
pulling/picking the association between the cues and the behavior will extinguish and the
cues will no longer evoke the urge to pick/pull (Hoogduin, 1997). With this repeated
exposure and expectancy violation on set of beliefs about the behavior and the urges, the
patients in the HRT-CERP group will get new information about the triggering stimuli.
Therefore, the patient will be more able to handle cues and triggers in the future and less
likely to relapse.
In conclusion, it can be argued that HRT-CERP is better able to prevent relapse after
treatment, compared to HRT-SC. Therefore, it was hypothesized that participants in HRT-
CERP would have maintained treatment gains better than participants in HRT-SC at one
month follow-up. Unfortunately, the follow-up measures were not available at the time when
this essay was due. These results will be reported elsewhere.
Mechanisms of Change
Despite small sample size, preliminary analyses were conducted to explore possible
mechanisms of change.
Cue-reactivity. Because CERP focuses on reducing cue-triggered urges and internal
experiences, it can be argued that CERP works in part by reducing cue-reactivity. To test
this, we administered a paper/pencil cue-reactivity test before and after treatments (Snorrason
et al., 2015). However, the paper/pencil cue-reactivity manipulation failed to induce cue
reactivity in this sample. Plausible reason for why it did not work might be because in this
study all the phenomenology questionnaires were translated to Icelandic and therefore might
have been a slight difference in the cue itself. For future researches there is a reason to
speculate that using different types of cues (e.g. pictures of skin imperfection or coarse hairs)
might provoke stronger cue-reactivity. The sample size was also rather small so repeating the
cue-reactivity test again with larger sample size might work.
34
Because the cue-reactivity manipulation failed to induce significant cue-reactivity it
was decided to examine if self-report scales assessing wanting and liking skin picking/hair
pulling (Snorrason et al., 2015; Snorrason et al., 2017) would mediate treatment effects,
particularly in CERP. The results showed that reduction in liking (but not wanting) scores
were significantly correlated with change in symptom severity in HRT-CERP, but not HRT-
SC. These results suggest HRT-CERP may reduce symptoms by reducing liking or
pleasurable experiences associated with picking/pulling episodes.
Automatic versus focused behavior. In the study, six out of ten participants that
received HRT-SC were considered to be primarily focused in their pulling and picking
behavior, against only three in the HRT-CERP group. Even though these behavior styles tend
to co-occur within an individual (most people experience both styles to some extent),
clinicians have speculated that the difference styles might preferentially respond to different
treatment interventions (Flessner et al; 2008; Walter, Flessner, Conelea, & Woods; 2009). In
particular, it can be argued that CERP, and other interventions that address internal
experiences, would be more suitable for individuals with primarily focused behavior. In
contrast, for individuals were the behavior is primarily automatic, HRT-SC could be more
suitable because it emphasizes awareness training (Flessner et al; 2008). There were total of
nine participants with primarily focused behavior in the study but unfortunately the
randomization didn’t divide them equally into the two treatment groups. For that reason
interpretation about a possible role of different types of the behavior is difficult to determine.
Limitations
There were a few limitations in the present study. First, the sample may have differed
from the general population on some characteristics. All participants were women, university
student and 19 out of 20 were Caucasian. So our sample was rather homogeneous and may
not have adequately reflected the general SPD/HPD clinical population. Secondly, the sample
size was small, only 20 participants divided equally to both treatment groups. There was also
no waiting-list/no-treatment condition to control for natural influences. The clinical
symptoms of participants in this study were similar to other studies, but the severity may have
been lower, as expected in a university population. Finally, another important limitation is
that although interviewers were blind to the treatment conditions, they were not blind to the
purpose of the study.
35
Strengths
The study also had its strengths. As far as we know this is the first study to compare
the efficacy of HRT-CERP and HRT-SC as a treatment for HPD/SPD. Treatment was
implemented by trained psychotherapists who were supervised in weekly meetings. Also
multiple outcome measures were used to assess symptom improvement, including self-report
scales, clinical interviews and photograph ratings.
Conclusions
The main conclusion from this study is that both HRT-SC and HRT-CERP are
effective interventions to treat both HPD and SPD. The efficacy of HRT-SC is similar to
prior studies (e.g. Schuck, Keijsers, & Rinck, 2011; Teng, Woods, & Twohig, 2006) but as
mentioned before, this is the first controlled trial study with HRT- CERP as a treatment
protocol for HPD/SPD. These results advocate the application of HRT-CERP. It will be
interesting to see the result of the follow-up evaluation, and if there is a difference in relapse
rate between the two conditions. If our hypothesis is supported it will further support
implementing HRT-CERP as a treatment protocol for HPD and SPD.
The challenge for the future is to compare these behavioral interventions with sample
that is closer to the general population and with a larger treatment groups. We also believe
that four treatment sessions might have been too short of an intervention, at least for some of
our participants. Thus, a similar study with more treatment sessions would be interesting.
HRT-CERP might also be compared to other type of interventions like pharmacotherapy and
some combination of both treatments. Furthermore, future researches should attempt to gain
more insight into the mechanisms of change like the role of cue-reactivity.
36
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45
Appendix
I
Table 1
Individual scores for each participant on both SPS-R/MGH-HS self-report scales and SPS-R-IV/MGH-
HS-IV clinical interview from before and after treatment
participants SPS-R/MGH-HS SPS-R-IV/MGH-HS-IV
Pre-assessment Post-assessment Pre-assessment Post-assessment
HPD
1 20 9 19 8
2 16 9 17 10
3 18 6 20 5
4 21 18 21 19
5 21 6 19 4
SPD
6 16 12 16 10
7 15 3 14 3
8 15 10 15 8
9 16 8 15 9
10 21 9 20 8
11 14 10 15 9
12 15 16 16 14
13 18 5 16 6
14 23 20 22 20
15 13 6 13 4
16 18 3 16 2
17 10 13 16 10
18 13 4 13 4
19 21 6 16 5
20 16 11 18 17
Note: Total score for MGH-HS/MGH-HS-IV is on the scale of 0-28. Total score for SPS-R/SPS-R-IV is
on the scale of 0-32.