Motor inhibition and cognitive flexibility in pathologic skin picking

Clinical Characteristics of Youth with Trichotillomania (Hair-Pulling Disorder) and Excoriation (Skin-Picking) Disorder

Body-focused repetitive disorders (BFRBDs) are understudied in youth and understanding of their underlying mechanisms is limited. This study evaluated BFRBD clinical characteristics, and two factors commonly implicated in their maintenance - emotion regulation and impulsivity - in 53 youth aged 11 to 17 years: 33 with BFRBDs and 20 controls. Evaluators administered psychiatric diagnostic interviews. Participants rated BFRBD severity, negative affect, quality of life, family functioning, emotion regulation, distress tolerance, and impulsivity. Youth with BFRBDs showed poorer distress tolerance and quality of life, and higher impulsivity and negative affect than controls, with no differences in family impairment. BFRBD distress/impairment, but not BFRBD severity, correlated with anxiety and depression, and poorer distress tolerance. Findings suggest youth with BFRBDs show clinical patterns aligning with prior research; highlight the role of distress tolerance in child BFRBDs; and suggest the utility of acceptance and mindfulness-based therapies for unpleasant emotions in BFRBDs. Continued research should evaluate factors underlying BFRBDs in youth.

Structural neuroimaging of skin-picking disorder

BACKGROUND

Skin-picking disorder (SPD) is conceptualized as an obsessive-compulsive and related disorder (OCRD). Patients with SPD excessively manipulate their skin, which leads to skin lesions, psychological distress, and functional impairment. The neuroanatomical facets of this disorder are still poorly understood.

METHODS

A total of 220 participants (123 patients with a primary diagnosis of SPD and 97 healthy controls; mean age = 30 years, 80% female) were recruited for a voxel-based morphometry (VBM) study. VBM data were compared between patients and controls, and between three SPD subgroups, each characterized by a distinct age of symptom onset (before puberty, during puberty, adulthood).

RESULTS

Relative to the healthy comparison group, patients with SPD had significantly less grey matter volume (GMV) in regions of interest (ROIs: insula, orbitofrontal cortex, pallidum, cerebellum, supramarginal gyrus) and in the frontal pole and occipital regions (whole-brain findings). Early onset of symptoms (before puberty) was associated with elevated levels of focused skin-picking, in addition to less GMV in specific ROIs (insula, orbitofrontal cortex) as well as in paracingulate/ superior temporal regions (whole-brain findings).

CONCLUSIONS

SPD-related reductions in GMV were identified in brain regions involved in interoception, emotion regulation, and motor control. This partially aligns with findings for OCD. The detection of different age-of-onset groups based on clinical as well as morphometric data points to the heterogeneity of the disorder and warrants further investigation.

Atypical cerebellar activity and connectivity during affective touch in adults with skin-picking disorder

Excessive touching and picking of one's skin are core symptoms of skin-picking disorder (SPD). Previous research has shown that patients with SPD display difficulties in motor control and show altered reward responsivity. Considering the limited knowledge about neuronal mechanisms in SPD, particularly concerning the cerebellum, the analysis focused on this brain region due to its involvement in sensorimotor and affective functions. The participants of the present study received affective (caress-like), which is typically perceived as pleasant and can be passively enjoyed. A total of 132 female participants (70 patients with SPD, 62 healthy controls) received affective and nonaffective touch to their forearms (slow vs. fast brushing) during functional magnetic resonance imaging. This tactile stimulation was rated according to pleasure, arousal, and the urge to pick one's skin. Being touched was perceived as more negative and arousing by the SPD group, and elicited a greater urge to perform skin-picking. During affective touch, those participants with SPD were characterized by reduced activity in lobule VIII, reduced functional connectivity of lobule VIII with the hippocampus, and increased connectivity with the superior parietal lobule. Since VIII is involved in the inhibition of movement, the present findings point to deficient motor control in SPD in the context of affective-sensory processing.

Negative Affectivity Moderates the Relationship between Attentional Control and Focused Skin Picking

Very little is known about the cognitive functioning of people with body-focused repetitive behaviours and the few existing studies provide mixed findings. The aim of this study was to investigate the interplay between attentional control, negative affectivity, and focused skin picking. We hypothesized that the control of attention is associated with focused style of skin picking and that this relationship is moderated by negative affectivity. The final sample consisted of 273 non-clinical subjects (79% women) aged 18 to 54 years; study variables were assessed using questionnaires. Moderation analysis was conducted, followed by a simple slope analysis, and the Johnson–Neyman technique was used to probe the interaction effect. We found that at the low level of negative affectivity, the relationship between attentional control and focused skin picking is negative, but not at the higher levels of this trait. Interestingly, when negative affectivity reaches very high intensity, the association between attentional control and skin picking becomes positive. This relationship seems to be quite complex and may depend on the way that cognitive abilities are used by the individual, as well as on the stage of cognitive processing that they are applied to. Further studies using behavioural measures of attention are needed to better understand this issue.

Trichotillomania and Skin-Picking Disorder: An Update

Trichotillomania (hair pulling disorder) and skin-picking (excoriation) disorder are common neuropsychiatric disorders (each with a point prevalence of around 2%) but are underrecognized by professionals. Affected individuals repeatedly pull out their own hair or pick at their skin, and these symptoms not only have a negative impact on these individuals because of the time they occupy but can also lead to considerable physical disfigurement, with concomitant loss of self-esteem and avoidance of social activities and intimate relationships. The behaviors may also have serious physical consequences. Trichotillomania and skin picking frequently co-occur, and both disorders commonly present with co-occurring depression, anxiety, impulsive, and obsessive-compulsive disorders. Behavioral therapy currently appears to be the most effective treatment for both. Pharmacotherapy, in the form of N-acetylcysteine or olanzapine, may also play a role in treatment.

Evaluating the role of Approach-Avoidance Training on action-tendencies in individuals with skin-picking disorder: A preliminary randomized experiment

BACKGROUND AND AIMS

Pathological skin-picking (PSP) or excoriation disorder is a destructive behavior that affects 1-2% of the general population. The purpose of this pilot study was to evaluate the effect of a computerized behavior modification task on action-tendencies (i.e., approach or avoidance) in adults with PSP. We aimed to modify these action-tendencies by having participants with PSP complete the Approach-Avoidance Training (AAT) task, using a joystick to simulate an approach (=pull) or avoidance (=push) response.

METHOD

Forty-five participants diagnosed with PSP were randomized to one of three training conditions: (1) Avoidance Training (AvT; n = 15), (2) Approach Training (ApT; n = 15), or (3) Placebo Training (PT; n = 15). We hypothesized that after training, those in the AvT would have the greatest reduction in behavioral approach (i.e., their overall reaction time [RT] to approach pictures of irregular skin stimuli).

RESULTS

Results of the pre-training assessment task revealed a positive correlation between behavioral approach to irregular skin stimuli and skin-picking severity as assessed by the Skin Picking Scale-Revised (SPS-R). After training, a lower behavioral approach and urges to pick were found in the AvT and PT groups, while those in the ApT reported higher behavioral approach and urges to pick. At two-week follow-up, no significant changes on the SPS-R were reported between groups.

DISCUSSION

Our preliminary data suggest that the AAT is a promising avenue of research to develop as a cognitive intervention to address an excessive behavioral approach tendency that characterizes skin-picking problems.

Shared and unique neural mechanisms underlying pediatric trichotillomania and obsessive compulsive disorder

BACKGROUND

Little is known about the neural underpinnings of pediatric trichotillomania (TTM). We examined error-related negativity (ERN)-amplitude and theta-EEG power differences among youth with TTM, OCD, and healthy controls (HC).

METHODS

Forty channel EEG was recorded from 63 pediatric participants (22 with TTM, 22 with OCD, and 19 HC) during the Eriksen Flanker Task. EEG data from inhibitory control were used to derive estimates of ERN amplitude and event-related spectral power associated with motor inhibition.

RESULTS

TTM and HC were similar in brain activity patterns in frontal and central regions and TTM and OCD were similar in the parietal region. Frontal ERN-amplitude was significantly larger in OCD relative to TTM and HC, who did not differ from each other. The TTM group had higher theta power compared to OCD in frontal and central regions, and higher theta than both comparison groups in right motor cortex and superior parietal regions. Within TTM, flanker task performance was correlated with EEG activity in frontal, central, and motor cortices whereas global functioning and impairment were associated with EEG power in bilateral motor and parietal cortices.

CONCLUSIONS

Findings are discussed in terms of shared and unique neural mechanisms in TTM and OCD and treatment implications.

Dermatillomania: Strategies for Developing Protective Biomaterials/Cloth

Dermatillomania or skin picking disorder (SPD) is a chronic, recurrent, and treatment resistant neuropsychiatric disorder with an underestimated prevalence that has a concerning negative impact on an individual’s health and quality of life. The current treatment strategies focus on behavioral and pharmacological therapies that are not very effective. Thus, the primary objective of this review is to provide an introduction to SPD and discuss its current treatment strategies as well as to propose biomaterial-based physical barrier strategies as a supporting or alternative treatment. To this end, searches were conducted within the PubMed database and Google Scholar, and the results obtained were organized and presented as per the following categories: prevalence, etiology, consequences, diagnostic criteria, and treatment strategies. Furthermore, special attention was provided to alternative treatment strategies and biomaterial-based physical treatment strategies. A total of six products with the potential to be applied as physical barrier strategies in supporting SPD treatment were shortlisted and discussed. The results indicated that SPD is a complex, underestimated, and underemphasized neuropsychiatric disorder that needs heightened attention, especially with regard to its treatment and care. Moreover, the high synergistic potential of biomaterials and nanosystems in this area remains to be explored. Certain strategies that are already being utilized for wound healing can also be further exploited, particularly as far as the prevention of infections is concerned.

Resting-State Functional Connectivity of Supplementary Motor Area Associated with Skin-Picking Symptom Severity

Pathological skin picking (excoriation) is a relatively common disorder. Although it has been hypothesized to share a similar pathophysiological basis as other obsessive-compulsive (OC) spectrum disorders, to date, little work has specifically examined the precise neurobiological mechanisms involved in excoriation. Disruption in functional circuits involving the right inferior frontal gyrus (rIFG) and supplementary motor area (SMA) may be particularly relevant to skin-picking pathology as these regions have been implicated in other OC-spectrum disorders for their roles in response inhibition and voluntary motor action, respectively. To this end, the present study examined the associations between skin-picking symptom severity and resting-state functional connectivity of the rIFG and bilateral SMA. Participants endorsing elevated symptoms of excoriation completed a self-report measure of symptom severity and resting-state functional magnetic resonance imaging scan. Results indicated that symptom severity was associated with weaker connectivity between the SMA and clusters within the orbitofrontal cortex and angular gyrus. Contrary to hypotheses, there were no effects of symptom severity on functional connectivity of the rIFG. Overall, these findings suggest that skin-picking symptom severity may be associated with disruption in higher-order motor networks contributing to deficits in top-down regulation of motor behavior.

Defining Subtypes in Children with Nail Biting: A Latent Profile Analysis of Personality

OBJECTIVE

This study aimed to examine personality profiles and behavioral problems of children with nail biting (NB) to gain insight into the developmental trajectory of pathological NB.

METHODS

681 elementary school students were divided into non NB (n=436), occasional NB (n=173) and frequent NB group (n=72) depending on the frequency of NB reported in Child Behavioral Checklist (CBCL). Children's personality was assessed using the Junior Temperament and Character Inventory (JTCI), and behavioral problems were assessed using the CBCL. Latent Profile Analysis (LPA) was performed using JTCI profiles to classify personalities of the children with NB (belonging to frequent and occasional NB group, n=245).

RESULTS

For subscale scores of CBCL, the total, internalizing, externalizing, anxious/depressed withdrawn/depressed, depression, thought, rule-breaking, and aggressive behavior problems, were most severe in the frequent NB group followed by occasional NB and non NB group. LPA of personality profile in children with NB revealed four classes ('adaptiveness,' 'high reward dependence,' 'low self-directedness,' and 'maldaptiveness'). The four personality classes demonstrated significant group differences in all of the CBCL subscales. Children who showed low self-directedness and cooperativeness and high novelty seeking and harm avoidance personality profiles demonstrated highest tendency for problematic behavior irrespective of the frequency of NB.

CONCLUSION

Children with NB reported significantly more problematic behaviors compared to children without NB. Children with specific personality profile demonstrated higher tendency for problematic behavior irrespective of the frequency of NB. Therefore, accompanying personality profiles should be considered when assessing behavioral problems in children with NB.

Disgust, shame and the psychosocial impact of skin picking: Evidence from an online support forum

This article examines the accounts of individuals who problematically pick their skin and explores their subjective experiences. In total, 100 problem disclosure statements were taken from posts made to a publicly accessible online skin picking support forum. These posts were systematically analysed using thematic analysis. Themes of disgust, shame and psychosocial avoidance dominated the analysis and appeared central to the experience of skin picking. Skin picking was shown to be a heterogeneous experience with a complex emotional profile. We argue that disgust, shame and related avoidance behaviour should be considered when conceptualising skin picking and considering treatment interventions.

Should skin picking disorder be considered a diagnostic category? A systematic review of the evidence

OBJECTIVES

The aim of this study was to conduct a systematic review of the literature to collect, analyse and synthesise the evidence on skin picking disorder as defined by Arnold's criteria or the Diagnostic and Statistical Manual of Mental Disorders - fifth edition (DSM-5) and to examine whether skin picking disorder warrants inclusion in the DSM-5 as a distinct disorder.

METHOD

The databases CINAHL, Medline, Embase and PsycINFO were searched for articles published between January 2008 and May 2018. Eligible articles were empirical studies that used Arnold's or DSM-5 criteria to diagnose skin picking disorder, published in English, with participants aged 18 years or older. The methodological quality of included studies was assessed according to the National Health and Medical Research Council's guidelines and suggested nosological classification of skin picking disorder were summarised. Eligible studies were assessed against the five criteria proposed by Blashfield and colleagues to determine the validity of the inclusion of skin picking disorder in the DSM-5.

RESULTS

A total of 20 studies were considered eligible out of 1554. Most of the papers were case-control studies with small clinical samples. Only one out of Blashfield's five criteria was met; there were commonly accepted diagnostic criteria and assessment scales present in the literature. However, at the time of review, the criterion of 50 published articles (25 of which are required to be empirical) was not met; there had been no publication specifically assessing the clinical utility or validity of skin picking disorder and no studies addressing the differentiation of skin picking disorder from other obsessive-compulsive and related disorders.

CONCLUSION

Only a small proportion of published studies on skin picking disorder have employed validated criteria. The current literature fulfills only one of Blashfield's five criteria for the inclusion of skin picking disorder as a specific entity in psychiatric diagnostic manuals. Further empirical studies on skin picking disorder are needed in order to substantiate skin picking disorder as a disorder distinct from related disorders under the obsessive-compulsive and related disorders category.

Skin picking in patients with obesity: Associations with impulsiveness and self-harm

Previous studies suggest elevated prevalence rates of skin picking and self-harm in patients with obesity compared to individuals in the general population. Hence, further studies should investigate prevalence rates and correlates of skin picking in this population - especially its differentiation to self-harm. Skin picking and obesity are both associated with specific facets of impulsiveness. This relation should be explored to shed light on potentially shared mechanisms in etiology. Therefore, the present study examined the occurrence of skin picking and its associations with impulsiveness and self-harm in a sample of pre-bariatric surgery patients with obesity class II/III. Within the routine preoperative psychiatric evaluation, a total of 139 bariatric surgery candidates (78% female, BMI range 35-69) completed a self-report questionnaire assessing sociodemographic variables, anxiety, depression, self-harm, impulsiveness, and skin picking severity (urges: frequency, intensity, controllability; behavior: frequency, intensity, controllability; resistance, emotional distress, impairment, and avoidance). Ten participants (7.2% of the sample) reported recurrent skin picking leading to skin damage, repeated attempts to decrease skin picking, and psychosocial impairment (emotional distress, impairment in functional areas, avoidance) due to skin picking. In line with previous findings, skin picking severity shows a medium correlation with attentional impulsiveness. The majority of self-harm types were not associated with skin picking severity. The current study reveals a high occurrence of skin picking compared to the general population. The results indicate an association between skin picking severity and attentional impulsiveness. Further research is needed to investigate the differentiation of skin picking and self-harm in more detail.

An fMRI Pilot Study of Cognitive Flexibility in Trichotillomania

Trichotillomania is a relatively common psychiatric condition, although its neurobiological basis is unknown. Abnormalities of flexible responding have been implicated in the pathophysiology of obsessive-compulsive disorder and thus may be relevant in trichotillomania. The purpose of this study was to probe reversal learning and attentional set-shifting in trichotillomania. Twelve adults with trichotillomania and 13 matched healthy control subjects undertook a functional MRI task of cognitive flexibility. Group-level activation maps for extradimensional and reversal switches were independently parcellated into discrete regions of interest using a custom watershed algorithm. Activation magnitudes were extracted from each region of interest and study subject and compared at the group level. Reversal events evoked the expected patterns of insula and parietal regions and activity in the frontal dorsal cortex extending anterior to the frontal poles, whereas extradimensional shifts evoked the expected frontal dorsolateral and parietal pattern of activity. Trichotillomania was associated with significantly increased right middle frontal and reduced right occipital cortex activation during reversal and set-shifting. Elevated frontal activation coupled with reduced activation in more posterior brain regions was identified. These pilot data suggest potentially important neural dysfunction associated with trichotillomania.

Neuroanatomical Correlates of Impulsive Action in Excoriation (Skin-Picking) Disorder

Excoriation (skin-picking) disorder (SPD) has similarities to obsessive-compulsive disorder (OCD) and is included within the obsessive-compulsive and related disorders (OCRD) diagnostic class in DSM-5. Separate neuroimaging and neurocognitive studies suggest that people affected by SPD find it difficult to inhibit dominant motor responses due to a failure of "top-down" control mechanisms. No study has examined the neural correlates of SPD in participants with varying degrees of impulsive motor behavior. This study correlated cortical thickness and volumes of selected subcortical structures with stop-signal task performance in participants with SPD (N=15) and in healthy control subjects (N=8). All participants were free from current psychiatric comorbidity, including OCD. In volunteers with SPD, longer stop-signal reaction times were correlated with cortical thinning in the right insula and right-inferior parietal lobe and with increased cortical thickness in the left-lateral occipital lobe, though these findings did not withstand correction for multiple comparisons. There were no significant correlations between cortical thickness in these three structures and stop-signal reaction times in the control group. This study suggests that structural abnormalities in the insular cortex and parietal and occipital regions may play a role in the pathophysiology of SPD. Further neuroimaging research is needed to understand the neurobiology of SPD and its relationship with other putative OCRDs.

Response inhibition and error-monitoring processes in individuals with obsessive-compulsive disorder

Response inhibition (RI) has been putatively linked to the symptoms of OCD. Despite the enticing link between RI and OCD, there are points in the relationship that require clarification. We examined the RI-OCD relationship taking into account a) the potentially differential pattern of RI-OCD relationship between obsessions and compulsions, and b) the potentially confounding effect of negative affect, particularly in regards to depression. Additionally, we investigated how error-monitoring processes in the inhibitory context account for OCD symptoms. Results showed that the RI-OCD relationship is robust in regards to compulsion symptoms, but not for obsessions, even when controlling for negative affect. Additionally, while individuals with OCD display behavioral slow-down following commission errors on the stop-signal task, slow-down following successful inhibition is significantly related to compulsion symptoms. Findings suggest that future studies investigating RI in OCD should take into account heterogeneous clinical presentations in OCD, as well as incorporate error-monitoring variables to better understand RI processes in OCD.

Neurocognitive Findings in Onychophagia (Pathological Nail Biting)

A notable number of people struggle to control the desire to bite their nails, resulting in impairment and distress. Understanding this behavior and the inability to control it has received little research attention. One possible mechanism to understand nail biting is through the use of neurocognitive assessments. Neurocognitive assessments of pathological nail biting, however, are lacking. This analysis assesses the clinical presentation and neurocognitive profile of adults with nail biting relative to participants without nail biting. A total of 87 participants (aged 18-29 years) were recruited for a study on nail biting in young adults. Participants completed diagnostic, self-report, and neurocognitive measures which assessed two cognitive domains - motor impulsivity and cognitive flexibility. In the sample, 34 participants reported current nail biting. The nail biting group showed no significant differences in impulsivity or cognitive flexibility compared to the healthy controls. The lack of association between nail biting and cognitive deficits suggests that perhaps identifying meaningful subtypes of nail biting that reflect distinct pathology from normal grooming behavior may be important.

A structural MRI study of excoriation (skin-picking) disorder and its relationship to clinical severity

Excoriation (skin-picking) disorder (SPD) shares symptomology with other obsessive-compulsive and related disorders. Few studies, however, have examined the neurological profile of patients with SPD. This study examined differences in cortical thickness and basal ganglia structural volumes between 20 individuals with SPD and 16 healthy controls using magnetic resonance imaging (MRI). There were no significant differences in demographic variables (age, gender, education and race) between groups. All subjects completed a structural MRI scan and completed a battery of clinical assessments focusing on SPD symptom severity, depression and anxiety symptoms, and quality of life. No statistically significant differences in basal ganglia (caudate, putamen, and nucleus accumbens) structural volumes were found between groups. In individuals with SPD, increasing impulsiveness correlated positively with increased cortical thickness in the left insula, and skin picking severity correlated negatively with cortical thickness in the left supramarginal gyrus and a region encompassing the right inferior parietal, right temporal and right supramarginal gyrus. This study suggests similarities and differences exist in symptomology between SPD and the other obsessive-compulsive and related disorders. Additional neuroimaging research is needed to better delineate the underlying neurobiology of SPD.

Genital Dermatillomania

Dermatillomania is a rare disease that seldom affects the genitals. Genital dermatillomania has not yet been recognized as a separate entity within the disease. The purpose of the report is to highlight a new facet of dermatillomania and inform urologists that dermatillomania could be a potential reason for genital ulcers. This report documents 2 cases of genital dermatillomania which vary in severity from mild (case 1), where the patient's ulcers healed after extensive counseling, to extremely dire (case 2), where the patient lost his penis after recurring ulcers and multiple reconstructive surgeries. Clinicians should be aware of the characteristics of dermatillomania to ensure that appropriate therapy can be promptly initiated to prevent morbidity.

Clinical correlates of symptom severity in skin picking disorder

BACKGROUND

Skin picking disorder (SPD) remains poorly understood with limited data regarding its underlying pathophysiology and appropriate treatment choices. One approach to refining our treatment of SPD might be to better understand the range of illness severity and the clinical associations with severity.

METHODS

125 adults aged 18 to 65 with a primary, current DSM-5 diagnosis of SPD were assessed for the severity of their picking, using the Skin Picking Symptom Assessment Scale, and related mental health symptoms. To identify clinical and demographic measures associated with variation in disease severity, we utilized the statistical technique of partial least squares (PLS).

RESULTS

Greater SPD symptom severity was associated with higher Barratt attentional impulsiveness and motor impulsivity, higher Eysenck impulsivity, higher state anxiety/depression, having a current anxiety disorder, and having a lifetime substance use disorder.

CONCLUSIONS

The present analysis is, to our knowledge, the most complete assessment of clinical variables and their relationship to illness severity in a sample of adults with SPD. Aspects of impulsivity and anxiety are both strongly associated with worse illness severity, and functional disability, in SPD. Treatment approaches should incorporate these as possible treatment targets when developing new treatment approaches to this disorder.

P300 Source Localization Contrasts in Body-Focused Repetitive Behaviors and Tic Disorders

Tic disorders (TD) and body-focused repetitive behaviors (BFRB) have similar phenotypes that can be challenging to distinguish in clinical settings. Both disorders show high rates of comorbid psychiatric conditions, dysfunctional basal ganglia activity, atypical cortical functioning in the prefrontal and motor cortical regions, and cognitive deficits. Clinicians frequently confound the two disorders and it is important to find reliable objective methods to discriminate TD and BFRB. Neuropsychological tests and event-related potential (ERP) studies have yielded inconsistent results regarding a possible context updating deficit in TD and BFRB patients. However, most previous studies did not control for the presence of comorbid psychiatric condition and medication status, which might have confounded the findings reported to date. Hence, we aimed to investigate the psychophysiology of working memory using ERP in carefully screened TD and BFRB patients excluding those with psychiatric comorbidity and those taking psychoactive medication. The current study compared 12 TD patients, 12 BRFB patients, and 15 healthy control participants using a motor oddball task (button press). The P300 component was analyzed as an index of working memory functioning. Results showed that BFRB patients had decreased P300 oddball effect amplitudes over the right hemisphere compared to the TD and control groups. Clinical groups presented different scalp distributions compared to controls, which could represent a potential endophenotype candidate of BFRB and TD.

Biological markers for anxiety disorders, OCD and PTSD: A consensus statement. Part II: Neurochemistry, neurophysiology and neurocognition

OBJECTIVE

Biomarkers are defined as anatomical, biochemical or physiological traits that are specific to certain disorders or syndromes. The objective of this paper is to summarise the current knowledge of biomarkers for anxiety disorders, obsessive-compulsive disorder (OCD) and posttraumatic stress disorder (PTSD).

METHODS

Findings in biomarker research were reviewed by a task force of international experts in the field, consisting of members of the World Federation of Societies for Biological Psychiatry Task Force on Biological Markers and of the European College of Neuropsychopharmacology Anxiety Disorders Research Network.

RESULTS

The present article (Part II) summarises findings on potential biomarkers in neurochemistry (neurotransmitters such as serotonin, norepinephrine, dopamine or GABA, neuropeptides such as cholecystokinin, neurokinins, atrial natriuretic peptide, or oxytocin, the HPA axis, neurotrophic factors such as NGF and BDNF, immunology and CO2 hypersensitivity), neurophysiology (EEG, heart rate variability) and neurocognition. The accompanying paper (Part I) focuses on neuroimaging and genetics.

CONCLUSIONS

Although at present, none of the putative biomarkers is sufficient and specific as a diagnostic tool, an abundance of high quality research has accumulated that should improve our understanding of the neurobiological causes of anxiety disorders, OCD and PTSD.

Behavioural addiction-A rising tide?

The term 'addiction' was traditionally used in relation to centrally active substances, such as cocaine, alcohol, or nicotine. Addiction is not a unitary construct but rather incorporates a number of features, such as repetitive engagement in behaviours that are rewarding (at least initially), loss of control (spiralling engagement over time), persistence despite untoward functional consequences, and physical dependence (evidenced by withdrawal symptoms when intake of the substance diminishes). It has been suggested that certain psychiatric disorders characterized by maladaptive, repetitive behaviours share parallels with substance addiction and therefore represent 'behavioural addictions'. This perspective has influenced the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), which now has a category 'Substance Related and Addictive Disorders', including gambling disorder. Could other disorders characterised by repetitive behaviours, besides gambling disorder, also be considered 'addictions'? Potential examples include kleptomania, compulsive sexual behaviour, 'Internet addiction', trichotillomania (hair pulling disorder), and skin-picking disorder. This paper seeks to define what is meant by 'behavioural addiction', and critically considers the evidence for and against this conceptualisation in respect of the above conditions, from perspectives of aetiology, phenomenology, co-morbidity, neurobiology, and treatment. Research in this area has important implications for future diagnostic classification systems, neurobiological models, and novel treatment directions.

Effects of stress on behavioral flexibility in rodents

Cognitive flexibility is the ability to switch between different rules or concepts and behavioral flexibility is the overt physical manifestation of these shifts. Behavioral flexibility is essential for adaptive responses and commonly measured by reversal learning and set-shifting performance in rodents. Both tasks have demonstrated vulnerability to stress with effects dependent upon stressor type and number of repetitions. This review compares the effects of stress on reversal learning and set-shifting to provide insight into the differential effect of stress on cognition. Acute and short-term repetition of stress appears to facilitate reversal learning whereas the longer term repetition of stress impairs reversal learning. Stress facilitated intradimensional set-shifting within a single, short-term stress protocol but otherwise generally impaired set-shifting performance in acute and repeated stress paradigms. Chronic unpredictable stress impairs reversal learning and set-shifting whereas repeated cold intermittent stress selectively impairs reversal learning and has no effect on set-shifting. In considering the mechanisms underlying the effects of stress on behavioral flexibility, pharmacological manipulations performed in conjunction with stress are also reviewed. Blocking corticosterone receptors does not affect the facilitation of reversal learning following acute stress but the prevention of corticosterone synthesis rescues repeated stress-induced set-shifting impairment. Enhancing post-synaptic norepinephrine function, serotonin availability, and dopamine receptor activation rescues and/or prevents behavioral flexibility performance following stress. While this review highlights a lack of a standardization of stress paradigms, some consistent effects are apparent. Future studies are necessary to specify the mechanisms underlying the stress-induced impairments of behavioral flexibility, which will aid in alleviating these symptoms in patients with some psychiatric disorders.

IMPAIRED EXECUTIVE FUNCTIONING IN PEDIATRIC TRICHOTILLOMANIA (HAIR PULLING DISORDER)

BACKGROUND

No neurocognitive examinations of pediatric trichotillomania (hair pulling disorder; HPD) have taken place. As a result, science's understanding of the underlying pathophysiology associated with HPD in youths is greatly lacking. The present study seeks to begin to address this gap in the literature via examination of executive functioning in a stimulant-free sample of children with HPD.

METHODS

Sixteen and 23 children between 9 and 17 years of age meeting DSM-5 diagnostic criteria for HPD or classified as a healthy control, respectively, were recruited (N = 39) to complete structured interviews, self-reports, and a subset of tests from the Cambridge Automatic Neurocognitive Test Assessment Battery (CANTAB) assessing cognitive flexibility/reversal learning (intradimensional/extradimensional; IED), working memory (spatial span; SSP), and planning and organization (Stocking of Cambridge; SOC).

RESULTS

Hierarchical regression analyses indicated that, after controlling for appropriate covariates, diagnostic status predicted impaired performance on both the IED (reversal learning only) and SOC (planning and organization) but failed to predict cognitive flexibility or working memory capacity. Correlational analyses revealed that pulling severity was strongly related to working memory capacity, while disparate relationships between pulling styles (automatic, focused pulling) were evident with respect to working memory and planning and organization.

CONCLUSIONS

Children with HPD performed more poorly on tasks of executive functioning as compared to controls. Correlational analyses suggest potentially distinct pathophysiology underlying automatic and focused pulling warranting further research. Limitations and future areas of inquiry are discussed.

Investigation of the Phenomenological and Psychopathological Features of Trichotillomania in an Italian Sample

Trichotillomania (TTM) is still a scarcely known and often inadequately treated disorder in Italian clinical settings, despite growing evidence about its severe and disabling consequences. The current study investigated the phenomenology of TTM in Italian individuals; in addition, we sought to examine patterns of self-esteem, anxiety, depression, and OCD-related symptoms in individuals with TTM compared to healthy participants. The current study represents the first attempt to investigate the phenomenological and psychopathological features of TTM in Italian hair pullers. One hundred and twenty-two individuals with TTM were enrolled: 24 were assessed face-to-face (face-to-face group) and 98 were recruited online (online group). An additional group of 22 face-to-face assessed healthy controls (HC group) was included in the study. The overall female to male ratio was 14:1, which is slightly higher favoring female than findings reported in literature. Main results revealed that a higher percentage of individuals in the online group reported pulling from the pubic region than did face-to-face participants; furthermore, the former engaged in examining the bulb and running the hair across the lips and reported pulling while lying in bed at higher frequencies than the latter. Interestingly, the online TTM group showed greater functional and psychological impairment, as well as more severe psychopathological characteristics (self-esteem, physiological and social anxiety, perfectionism, overestimation of threat, and control of thoughts), than the face-to-face one. Differences between the two TTM groups may be explained by the anonymity nature of the online group, which may have led to successful recruitment of more serious TTM cases, or fostered more open answers to questions. Overall, results revealed that many of the phenomenological features of Italian TTM participants matched those found in U.S. clinical settings, even though some notable differences were observed; therefore, cross-cultural invariance might represent a characteristic of OCD-related disorders.

Impulsivity in body-focused repetitive behavior disorders: Disparate clinical associations between three distinct measures

OBJECTIVE

Research on trichotillomania (TTM) and excoriation (skin-picking) disorder (SPD) has suggested that impulsivity may be an important cognitive underpinning of the behavior, but many studies have produced mixed results. This analysis assessed impulsivity in TTM and SPD using three measures: the Barratt Impulsiveness Scale (BIS), the Eysenck Impulsiveness Questionnaire (EIQ), and the Stop-Signal Task (SST).

METHODS

Two hundred and eighty three subjects with TTM or SPD completed measurement of impulsivity as a part of participation in several research studies. Subjects scoring one standard deviation above or below measure means were included in the analysis for that scale (SST: N = 45; EIQ: N = 32; BIS: N = 34). High and low impulsive groups were compared within measures on demographic, clinical, and behavioral variables.

RESULTS

Results differed by group, with domains of the BIS showing associations with clinical severity, quality of life, and anxiety, and the SST showing several differences, but not clinical severity. The EIQ domains showed no significant differences. No groups differed demographically.

CONCLUSIONS

These results suggest that the EIQ, BIS, and SST assess distinct characteristics. Notably, only the attentional domain from the BIS predicted higher severity scores. Future research needs to clarify the ideal utility for these scales as they relate to TTM and SPD. Key points The BIS, EIQ, and SST domains are associated with distinct clinical differences between high and low impulsivity groups. Only the subjects in the high attentional impulsivity domain of the BIS showed significantly elevated symptom severity. The high and low impulsivity groups within the EIQ domains did not show any significant differences. These disparate associations may indicate the need for better subtyping of impulsivity, as different measures of specific domains appear to show associations with distinct features.

Skin picking disorder with co-occurring body dysmorphic disorder

There is clinical overlap between skin picking disorder (SPD) and body dysmorphic disorder (BDD), but little research has examined clinical and cognitive correlates of the two disorders when they co-occur. Of 55 participants with SPD recruited for a neurocognitive study and two pharmacological studies, 16 (29.1%) had co-occurring BDD. SPD participants with and without BDD were compared to each other and to 40 healthy volunteers on measures of symptom severity, social functioning, and cognitive assessments using the Stop-signal task (assessing response impulsivity) and the Intra-dimensional/Extra-dimensional Set Shift task (assessing cognitive flexibility). Individuals with SPD and BDD exhibited significantly worse picking, significantly worse overall psychosocial functioning, and significantly greater dysfunction on aspects of cognitive flexibility. These results indicate that when SPD co-occurs with BDD unique clinical and cognitive aspects of SPD may be more pronounced. Future work should explore possible subgroups in SPD and whether these predict different treatment outcomes.

Cognitive flexibility differentiates young adults exhibiting obsessive-compulsive behaviors from controls

The National Institute of Mental Health has proposed a shift toward classifying clusters of disorders on the basis of underlying biomarkers and neurological correlates. The present study sought to determine whether cognitive flexibility represents one such construct underlying obsessive-compulsive behaviors (OCBs), a cluster of behaviors characteristic of OCD and other body-focused repetitive behaviors (BFRBs), including trichotillomania, pathological skin picking, nail biting, and tic disorders. One-hundred and twenty-four undergraduate students completed the Depression Anxiety and Stress Scales, Padua Inventory-Washington State University Revision, Massachusetts General Hospital-Hairpulling Scale, Skin Picking Scale, and an Intradimensional/Extradimensional Shift (IDED) Test. Analyses were performed using a subsample of participants who met criteria for inclusion in the OCB group and a control group (N=56). Results indicated that young adults in the OCB group demonstrated significantly poorer performance on the IDED compared to controls. However, hierarchical regression analyses revealed that increased deficits in cognitive flexibility failed to predict worsened OCB severity-as assessed via a composite score. These results suggest that while cognitive flexibility differentiates those exhibiting OCBs from controls, it does not appear to be related to OCB severity. Future research is needed to replicate these results in larger clinical samples.

An Examination of Executive Functioning in Young Adults Exhibiting Body-Focused Repetitive Behaviors

Body-focused repetitive behaviors (BFRBs), including hair pulling, nail biting, and skin picking are repetitive, habitual, and compulsive in nature. Although characteristic of disorders such as trichotillomania and skin picking disorder, BFRBs are associated with other psychiatric conditions as well. To date, research has failed to examine neurocognitive risk factors, particularly executive functioning, implicated in BFRBs utilizing a transdiagnostic approach. The present study recruited 53 participants (n = 27 demonstrating BFRBs and n = 26 randomly selected controls) from a larger sample of young adults. Participants completed an automated neurocognitive test battery including tasks of cognitive flexibility, working memory, and planning and organization. Results revealed that participants in the BFRB group demonstrated significantly poorer cognitive flexibility (d = 0.63) than controls. No differences were noted in other neurocognitive domains. However, planning and organization demonstrated a significant relationship with various BFRB severity measures. Implications, limitations, and avenues for further research are discussed.

An interrogation of cognitive findings in pediatric obsessive-compulsive and related disorders

Current findings in the field of psychology have led to increased interest and a new conceptualization of disorders characterized by repetitive behaviors, namely the obsessive compulsive and related disorders (OCRDs). Scant research, however, has sought to collect and categorize the extant research on pediatric OCRDs. Particularly, no adequate review of the pediatric cognitive literature existed until now, despite the clear implication of abnormalities in neuroanatomical structures and cognitive functioning in adult samples. While evidence for cognitive dysfunction in pediatric samples is presented, this paper also suggests that differences in cognitive dysfunction may indeed exist between adults and youth with OCRDs. Specifically, those irregularities present in said youth at varying developmental stages may impact the origination and maintenance of OCRDs across time. Finally, this paper seeks to formulate potential future goals for the research field, particularly through transdiagnostic approaches to processes linked with symptom presentations. This is of particular importance as an improved understanding of the interaction of cognitive function and growth is key to further comprehension of the OCRDs.

Excoriation disorder: impulsivity and its clinical associations

Excoriation disorder is the repetitive scratching or picking of skin that leads to physical damage, distress, and functional impairment. Skin picking has been associated with impulsivity and problems with inhibition. We hypothesized that problems in these areas could be disease severity markers. We recruited 73 adults meeting DSM-5 criteria for excoriation disorder, and 50 adult controls. Those with excoriation disorder were categorized as either "high impulsive" (HI) or "low impulsive" (LI) using either a neurocognitive task of motor impulsivity (Stop Signal Task) or the Barratt Impulsiveness Scale's (BIS-11) motor impulsivity subscale. The HI subjects, based on the BIS-11, showed higher urges scores, anxiety, and depressive symptoms. These data suggest that impulsivity may reflect a specific clinical presentation among those with excoriation disorder, but the clinical characteristics differ depending upon the impulsivity measure used. Agreement on how to measure various domains of impulsivity may be important in better understanding the disorder psychopathology and so improve future treatments.

Gambling disorder and other behavioral addictions: recognition and treatment

Addiction professionals and the public are recognizing that certain nonsubstance behaviors--such as gambling, Internet use, video-game playing, sex, eating, and shopping--bear resemblance to alcohol and drug dependence. Growing evidence suggests that these behaviors warrant consideration as nonsubstance or "behavioral" addictions and has led to the newly introduced diagnostic category "Substance-Related and Addictive Disorders" in DSM-5. At present, only gambling disorder has been placed in this category, with insufficient data for other proposed behavioral addictions to justify their inclusion. This review summarizes recent advances in our understanding of behavioral addictions, describes treatment considerations, and addresses future directions. Current evidence points to overlaps between behavioral and substance-related addictions in phenomenology, epidemiology, comorbidity, neurobiological mechanisms, genetic contributions, responses to treatments, and prevention efforts. Differences also exist. Recognizing behavioral addictions and developing appropriate diagnostic criteria are important in order to increase awareness of these disorders and to further prevention and treatment strategies.

Animal models of obsessive-compulsive spectrum disorders

Obsessive-compulsive disorder (OCD) and related conditions (trichotillomania, pathological skin-picking, pathological nail-biting) are common and disabling. Current treatment approaches fail to help a significant proportion of patients. Multiple tiers of evidence link these conditions with underlying dysregulation of particular cortico-subcortical circuitry and monoamine systems, which represent targets for treatment. Animal models designed to capture aspects of these conditions are critical for several reasons. First, they help in furthering our understanding of neuroanatomical and neurochemical underpinnings of the obsessive-compulsive (OC) spectrum. Second, they help to account for the brain mechanisms by which existing treatments (pharmacotherapy, psychotherapy, deep brain stimulation) exert their beneficial effects on patients. Third, they inform the search for novel treatments. This article provides a critique of key animal models for selected OC spectrum disorders, beginning with initial work relating to anxiety, but moving on to recent developments in domains of genetic, pharmacological, cognitive, and ethological models. We find that there is a burgeoning literature in these areas with important ramifications, which are considered, along with salient future lines of research.

New developments in human neurocognition: clinical, genetic, and brain imaging correlates of impulsivity and compulsivity

Impulsivity and compulsivity represent useful conceptualizations that involve dissociable cognitive functions, which are mediated by neuroanatomically and neurochemically distinct components of cortico-subcortical circuitry. The constructs were historically viewed as diametrically opposed, with impulsivity being associated with risk-seeking and compulsivity with harm-avoidance. However, they are increasingly recognized to be linked by shared neuropsychological mechanisms involving dysfunctional inhibition of thoughts and behaviors. In this article, we selectively review new developments in the investigation of the neurocognition of impulsivity and compulsivity in humans, in order to advance our understanding of the pathophysiology of impulsive, compulsive, and addictive disorders and indicate new directions for research.

Where on the obsessive impulsive-compulsive spectrum does hair-pulling disorder belong?

OBJECTIVE

Hair-pulling disorder (HPD) is a putative obsessive-compulsive spectrum disorder, but proper categorization is challenging. Distinct subgroups of HPD may exist, depending on the primary motivation in the act of pulling. Two notable proposed subgroups are "relief pullers" (pulling primarily to reduce anxiety- a "compulsive" subgroup) and "pleasure/gratification pullers" (pulling primarily for reward- an "impulsive" subgroup) which we sought to examine in order to contribute to conversations on the categorization of HPD.

METHODS

A total of 111 HPD subjects (mean age 33.7 ± 10.7 [range 18-61] years; 87.4% female) were included. Demographic and clinical characteristics were compared between subgroups (pleasure: n = 51; relief: n = 60); and cognitive performance where data were available (n = 29 per group) and 32 matched healthy controls.

RESULTS

No significant demographic differences were noted between groups. Pleasure pullers were significantly more conscious of their pulling. Response inhibition and set shifting deficits were noted in HPD versus controls; however, pleasure and relief pullers did not differ significantly from each other on neurocognitive measures.

CONCLUSIONS

The results suggest common clinical features and associated neural dysfunction between relief and pleasure/gratification pullers, rather than supporting their existence as discrete clinical entities. Selection of appropriate treatment may focus on other aspects of hair pulling, including family history and comorbidity.

Noradrenergic modulation of cognition: therapeutic implications

The noradrenaline (norepinephrine) system exerts profound influences on cognition via ascending projections to the forebrain, mostly originating from the locus coeruleus. This paper provides an overview of available infrahuman and healthy human studies, exploring the effects of specific noradrenergic manipulations on dissociable cognitive functions, including attention, working memory, cognitive flexibility, response inhibition and emotional memory. Remarkable parallels across species have been reported which may account for the mechanisms by which noradrenergic medications exert their beneficial effects in disorders such as depression and attention-deficit hyperactivity disorder (ADHD). The literature is discussed in relation to prevailing models of noradrenergic influences over cognition and novel therapeutic directions, including in relation to investigating the effects of noradrenergic manipulations on other disorders characterized by impulsivity, and dementias. Unanswered questions are also highlighted, along with key avenues for future research, both proof-of-concept and clinical.

White matter abnormalities in skin picking disorder: a diffusion tensor imaging study

Skin picking disorder (SPD) is characterized by the repetitive and compulsive picking of skin, resulting in tissue damage. Neurocognitive findings in SPD implicate difficulty with response inhibition (suppression of pre-potent motor responses). This function is dependent on the integrity of the right frontal gyrus and the anterior cingulate cortices, and white-matter tracts connecting such neural nodes. It was hypothesized that SPD would be associated with reduced fractional anisotropy in regions implicated in top-down response suppression, particularly white-matter tracts in proximity of the bilateral anterior cingulate and right frontal (especially orbitofrontal and inferior frontal) cortices. 13-subjects meeting proposed SPD criteria for DSM-5 free from other current psychiatric comorbidities, and 12 healthy comparison subjects underwent MRI with a 3-T system. Between-group comparisons of imaging data underwent voxelwise analysis with permutation modeling and cluster correction. Fractional anisotropy (measured using diffusion tensor imaging) was the primary outcome measure. Subjects with SPD exhibited significantly reduced fractional anisotropy in tracts distributed bilaterally, which included the anterior cingulate cortices. Fractional anisotropy did not correlate significantly with SPD disease severity, or depressive or anxiety scores. These findings implicate disorganization of white-matter tracts involved in motor generation and suppression in the pathophysiology of SPD, findings remarkably similar to those previously reported in trichotillomania. This study adds considerable support to the notion that-in addition to the phenomenological and comorbid overlap between SPD and trichotillomania-these disorders likely share overlapping neurobiology.

Age at onset in trichotillomania:clinical variables and neurocognitive performance

OBJECTIVE

Trichotillomania (TTM), or compulsive hair pulling, is a common psychiatric disorder characterized by psychosocial impairment and reduced quality of life. The aim of this retrospective study was to characterize the impact of age at TTM onset on clinical variables and neuropsychological function using a variety of clinical and neurocognitive measures.

METHOD

The study sample included 98 adult treatment-seeking individuals with a DSM-IV diagnosis of TTM. Correlates were explored by grouping participants into childhood-onset (onset at ≤ 11 years old, n = 42) or later-onset (≥ 12 years old, n = 56) TTM and via linear regression. All subjects underwent a semistructured clinical interview with a psychiatrist and completed a variety of paper-pencil tests regarding TTM severity and quality of life. A subset (n = 44) of subjects underwent neurocognitive testing assessing motor inhibition and set-shifting compared to a sample (n = 27) of age- and gender-matched healthy controls. Data were collected from September 2006 through July 2011.

RESULTS

Postpubertal age at onset was significantly associated with greater TTM symptom severity. Clinically, the later-onset group pulled their hair for a significantly greater amount of time daily (P = .008), had higher clinician-rated TTM severity on the Clinical Global Impressions-Severity of Illness scale (P = .042), and had higher patient-rated severity on the Massachusetts General Hospital Hairpulling Scale (P = .022) compared to healthy controls. On the neurocognitive tasks, later-onset TTM was characterized by stop-signal impairments (P = .020) and relatively spared set-shifting, consistent with previous studies in the literature. In contrast, the childhood-onset manifestation was associated with set-shifting deficits in stages of the task completed and total errors adjusted (both P < .001) but relatively spared stop-signal performance compared to healthy controls.

CONCLUSION

Results indicate that childhood-onset of TTM is common, as confirmed by the fact that 42.9% of our sample met childhood-onset criteria, and may differ neurobiologically from the prototypical later-onset form. Future neurobiological and treatment studies should measure age at onset and explore further these putative differences.Trial Registration ClinicalTrials.gov identifiers: NCT00354770 and NCT00775229.

Motor inhibition and cognitive flexibility in eating disorder subtypes

Anorexia Nervosa (AN) and Bulimia Nervosa (BN) are complex Eating Disorders (EDs). Even if are considered two different diagnostic categories, they share clinical relevant characteristics. The evaluation of neurocognitive functions, using standardized neuropsychological assessment, could be a interesting approach to better understand differences and similarities between diagnostic categories and clinical subtypes in EDs thus improving our knowledge of the pathophisiology of EDs spectrum. This study explored cognitive flexibility and motor inhibition in patients with AN considering both Restricter and Binge/Purge subtypes, patients with BN and healthy comparisons subjects (HC). Intra-Extra Dimentional Set shifting Test and Stop Signal Task, selected from CANTAB battery, were administered to analyzed set-shifting and motor inhibition respectively. AN patients showed a deficient motor inhibition compared to HC, while no evidence for impaired motor inhibition was found in BN patients; a significant relationship between commission errors in the Stop Signal Task and attentional impulsiveness was found. Moreover, no difference in set-shifting abilities was found comparing all clinician groups and HC. So our results indicated no cognitive impairment in these two cognitive functions in BN patients, while AN and BN showed different performances in motor inhibition. A similar cognitive profile was found in other obsessive compulsive spectrum disorders. Finally, the paper suggests a new interactive approach for the study of cognitive profile in psychiatric disorders; it might be more useful since it is more closely related to the executive functions complexity.

Implicit processes in pathological skin picking: responses to skin irregularities predict symptom severity and treatment susceptibility

BACKGROUND AND OBJECTIVES

Implicit cognitive processes are relevant in understanding the development and maintenance of psychopathology and dysfunctional behaviours. The present study investigated the role of implicit processes in pathological skin picking (PSP).

METHODS

Using an Approach-Avoidance Task (AAT), we examined automatic response tendencies towards skin picking-related photographs in a sample of 34 college students who suffered from PSP and participated in a randomized, waiting-list controlled treatment study.

RESULTS

In comparison to a control sample (n = 49), PSP patients displayed significantly decelerated reaction times (distraction) in response to photographs of skin irregularities and a tendency to respond with avoidance to photographs of skin irregularities. Both distraction and avoidance in reaction to photographs of skin irregularities were significantly associated with current skin picking severity. Moreover, the strength of distraction in response to skin irregularities predicted unique variance in skin picking severity at post-measurement, over and above the effect of skin picking severity at pre-measurement and the effect of treatment condition. For the treatment condition, higher initial distraction predicted better treatment outcome (lower skin picking severity at post-measurement), whereas it predicted symptom deterioration at post-treatment for untreated participants.

LIMITATIONS

The specific characteristics of PSP patients (mainly female university students) and the relatively small sample size may compromise generalizability of findings.

CONCLUSIONS

In PSP, affective distraction in response to skin irregularities seems to characterize an important process related to symptom severity as well as treatment susceptibility.

Similar hyporesponsiveness of the dorsomedial prefrontal cortex in problem gamblers and heavy smokers during an inhibitory control task

BACKGROUND

Behavioral addictions like pathological gambling share many clinical characteristics with substance dependence. In addition, both types of disorders are associated with impairments in inhibitory control. Studies in patients with substance use disorders point to hyporesponsiveness of the dorsomedial prefrontal cortex. However, no such data exist on behavioral addictions.

METHODS

Using functional magnetic resonance imaging, we investigated the neural circuitry associated with impaired response inhibition in a group of male problem gamblers (n=17) using a stop signal task. We included control conditions tailored to specifically isolate neural correlates of inhibitory control. To investigate the specificity of effects, a group of heavy smokers (n=18) and a group of healthy controls (n=17) were also included.

RESULTS

Groups did not differ in behavioral performance on the stop signal task. However, both problem gamblers and heavy smokers showed hyporesponsiveness of the dorsomedial prefrontal cortex compared to healthy controls, during successful as well as failed response inhibition. These effects were robust against adjustments for depression and adult attention deficit scores.

CONCLUSIONS

These findings suggest that hypoactivation of the inhibition circuit is a shared neural mechanism in substance use disorders and behavioral addictions. As such, they support the reclassification of pathological gambling as a behavioral addiction in DSM-V.

A cognitive comparison of pathological skin picking and trichotillomania

OBJECTIVE

Pathological Skin Picking (PSP) and Trichotillomania (TTM) share overlapping comorbidity and phenomenology. The extent to which these disorders share a common cognitive phenotype, however, has yet to be examined. This study sought to compare inhibitory control processes in individuals with PSP or TTM.

METHODS

Thirty-one subjects with PSP (mean age 31.2 ± 12.5 years; 93.5% female), 39 subjects with TTM (mean age 35.9 ± 10.7 years; 87.2% female), and 33 matched controls (mean age 31.9 ± 9.9 years; 72.7% female) undertook cognitive assessments using the Stop-Signal Task (assessing response impulsivity) and the Intra-dimensional/Extra-dimensional (ID/ED) Set Shift task (assessing cognitive flexibility). Groups were matched for age, gender, race/ethnicity, and education.

RESULTS

PSP was associated with significantly impaired stop-signal reaction times but intact ID/ED cognitive flexibility compared to controls. TTM occupied an intermediate position in terms of stop-signal reaction times between controls and PSP but did not differ significantly from either group on the ID/ED Set Shift Task.

CONCLUSION

These results replicate the finding of impaired inhibitory control in PSP but suggest TTM may be heterogeneous with respect to such impairment. Future work should explore possible subgroups in TTM and whether cognitive variables are predictive of treatment outcomes.

Motor inhibition, reflection impulsivity, and trait impulsivity in pathological skin picking

Pathological skin picking (PSP) is often recognized as an impulse control disorder. The current study sought to investigate the relationship between PSP and different forms of impulsivity. University students that met criteria for PSP (n = 55) and university students without history of PSP (n = 55) answered a multidimensional impulsivity questionnaire (the UPPS Impulsive Behavior Scale) and completed 2 neurocognitive tasks that assess impulsivity (the Stop Signal Task and the Information Sampling Task). The PSP group scored significantly higher than the control group on the negative and positive urgency subscales of the UPPS, but the groups did not differ on other subscales or the neurocognitive tasks. Logistic regression demonstrated that the urgency scales added to the prediction of PSP after negative affect and other forms of impulsivity were adjusted for. The results indicate that PSP sufferers are characterized by emotion-based impulsivity and do not appear to be impulsive in other ways.