Psychometric evaluation of the appearance anxiety inventory in adolescents with body dysmorphic disorder.

The Appearance Anxiety Inventory (AAI) is a self-report measure assessing the typical cognitions and behaviours of body dysmorphic disorder (BDD). Despite its use in research and clinical settings, its psychometric properties have not been evaluated in young people with BDD. We examined the factor structure, reliability, validity, and sensitivity to change of the AAI in 182 youths with BDD (82.9% girls; Mage = 15.56, SD = 1.37) consecutively referred to two specialist outpatient clinics in Stockholm, Sweden (n = 97) and London, England (n = 85). An exploratory factor analysis identified three factors, namely "threat monitoring", "camouflaging", and "avoidance", explaining 48.15% of the variance. The scale showed good internal consistency (McDonalds omega = 0.83) and adequate convergent validity with the Yale-Brown Obsessive-Compulsive Scale Modified for Body Dysmorphic Disorder for Adolescents (BDD-YBOCS-A; rs = 0.42) and the Clinical Global Impression-Severity Scale (rs = 0.32). Sensitivity to change was adequate, with AAI total scores and individual factor scores significantly decreasing over time in the subgroup of participants receiving multimodal treatment for BDD (n = 79). Change of AAI scores over treatment showed a positive statistically significant moderate-to-good correlation (r = 0.55) with changes in BDD symptom severity, measured by the BDD-YBOCS-A. The study provides empirical support for the use of the AAI in young people with BDD in clinical settings.

Psychometric Evaluation of the Yale-Brown Obsessive-Compulsive Scale Modified for Body Dysmorphic Disorder for Adolescents (BDD-YBOCS-A).

The Yale-Brown Obsessive-Compulsive Scale Modified for Body Dysmorphic Disorder for Adolescents (BDD-YBOCS-A) is a clinician-rated measure of BDD symptom severity in youth. Despite widespread use in both research and clinical practice, its psychometric properties have not been formally evaluated. The current study examined the factor structure, reliability, validity, and sensitivity to change of the BDD-YBOCS-A in 251 youths with BDD attending two specialist clinics. A principal component analysis identified two factors, explaining 56% of the variance. The scale showed good internal consistency (Cronbach's alpha = 0.87) and adequate convergent and divergent validity. In a subgroup of participants receiving BDD treatment (n = 175), BDD-YBOCS-A scores significantly decreased over time, demonstrating sensitivity to change. BDD-YBOCS-A change scores over treatment were highly correlated with severity changes measured by the Clinical Global Impression - Severity scale (r = .84). The study provides empirical support for the use of the BDD-YBOCS-A in children and adolescents with BDD.

Effectiveness of Multimodal Treatment for Young People With Body Dysmorphic Disorder in Two Specialist Clinics.

Body dysmorphic disorder (BDD) typically originates in adolescence and is associated with considerable adversity. Evidence-based treatments exist but research on clinical outcomes in naturalistic settings is extremely scarce. We evaluated the short- and long-term outcomes of a large cohort of adolescents with BDD receiving specialist multimodal treatment and examined predictors of symptom improvement. We followed 140 young people (age range 10-18) with a diagnosis of BDD treated at two national and specialist outpatient clinics in Stockholm, Sweden (n = 96) and London, England (n = 44), between January 2015 and April 2021. Participants received multimodal treatment consisting of cognitive behavior therapy and, in 72% of cases, medication (primarily selective serotonin reuptake inhibitors). Data were collected at baseline, posttreatment, and 3, 6, and 12 months after treatment.The primary outcome measure was the clinician-rated Yale-Brown Obsessive-Compulsive Scale Modified for BDD, Adolescent version (BDD-YBOCS-A). Secondary outcomes included self-reported measures of BDD symptoms, depressive symptoms, and global functioning. Mixed-effects regression models showed that BDD-YBOCS-A scores decreased significantly from baseline to posttreatment (coefficient [95% confidence interval] = -16.33 [-17.90 to -14.76], p<0.001; within-group effect size (Cohen's d) = 2.08 (95% confidence interval, 1.81 to 2.35). At the end of the treatment, 79% of the participants were classified as responders and 59% as full or partial remitters. BDD symptoms continued to improve throughout the follow-up. Improvement was also seen on all secondary outcome measures. Linear regression models identified baseline BDD symptom severity as a predictor of treatment outcome at posttreatment, but no consistent predictors were found at the 12-month follow-up. To conclude, multimodal treatment for adolescent BDD is effective in both the short- and long-term when provided flexibly within a specialist setting. Considering the high personal and societal costs of BDD, specialist care should be made more widely available.

Clinical characteristics of 172 children and adolescents with body dysmorphic disorder.

Body dysmorphic disorder (BDD) often starts in childhood, with most cases developing symptoms before age 18. Yet, BDD research has primarily focused on adults. We report the clinical characteristics of the world's largest cohort of carefully diagnosed youths with BDD and focus on previously unexplored sex and age differences. We systematically collected clinical data from 172 young people with BDD consecutively referred to 2 specialist pediatric obsessive-compulsive and related disorders outpatient clinics in Stockholm, Sweden and in London, England. A series of clinician-, self-, and parent-reported measures were administered. The cohort consisted of 136 girls, 32 boys, and 4 transgender individuals (age range 10-19 years). The mean severity of BDD symptoms was in the moderate to severe range, with more than one third presenting with severe symptoms and more than half showing poor or absent insight/delusional beliefs. We observed high rates of current psychiatric comorbidity (71.5%), past or current self-harm (52.1%), suicide attempts (11.0%), current desire for cosmetic procedures (53.7%), and complete school dropout (32.4%). Compared to boys, girls had significantly more severe self-reported BDD symptoms, depression, suicidal thoughts, and self-harm. Compared to the younger participants (14 or younger), older participants had significantly more severe compulsions and were more likely to report a desire for conducting cosmetic procedures. Adolescent BDD can be a severe and disabling disorder associated with significant risks and substantial functional impairment. The clinical presentation of the disorder is largely similar across sexes and age groups, indicating the importance of early detection and treatment. More research is needed specifically focusing on boys and pre-pubertal individuals with BDD.

Are body dysmorphic symptoms dimensional or categorical in nature? A taxometric investigation in adolescents.

Body dysmorphic disorder (BDD) is a debilitating mental health condition which usually emerges during adolescence and is characterised by distressing and impairing appearance concerns. It is currently unclear whether body dysmorphic concerns represent an extreme manifestation of normal appearance concerns (a dimensional conceptualisation), or whether they are qualitatively distinct (a categorical conceptualisation). This study aimed to determine whether body dysmorphic symptoms are dimensional or categorical in nature by investigating the latent structure using taxometric procedures. Body dysmorphic symptoms were assessed using validated measures among 11-16-year-old school pupils (N=707). Items of the Body Image Questionnaire Child and Adolescent version were used to construct four indicators that broadly corresponded to the DSM-5 diagnostic criteria for BDD (appearance concerns, repetitive behaviours, impairment, and insight). Indicators were submitted to three non-redundant taxometric procedures (MAMBAC, MAXEIG and L-MODE). Overall, results of all three taxometric procedures indicated a dimensional latent structure of body dysmorphic symptoms. The current study provides preliminary evidence that body dysmorphic symptoms are continuously distributed among adolescents, with no evidence of qualitative differences between mild and severe symptoms. Implications for clinical practice and research are discussed.

Empirically defining treatment response and remission in body dysmorphic disorder.

BACKGROUND: The number of clinical trials in body dysmorphic disorder (BDD) has steadily increased in recent years. As the number of studies grows, it is important to define the most empirically useful definitions for response and remission in order to enhance field-wide consistency and comparisons of treatment outcomes across studies. In this study, we aim to operationally define treatment response and remission in BDD. METHOD: We pooled data from three randomized controlled trials of cognitive-behavior therapy (CBT) for BDD (combined n = 153) conducted at four academic sites in Sweden, the USA, and England. Using signal detection methods, we examined the Yale-Brown Obsessive Compulsive Scale modified for BDD (BDD-YBOCS) score that most reliably identified patients who responded to CBT and those who achieved remission from BDD symptoms at the end of treatment. RESULTS: A BDD-YBOCS reduction ⩾30% was most predictive of treatment response as defined by the Clinical Global Impression (CGI) - Improvement scale (sensitivity 0.89, specificity 0.91, 91% correctly classified). At post-treatment, a BDD-YBOCS score ⩽16 was the best predictor of full or partial symptom remission (sensitivity 0.85, specificity 0.99, 97% correctly classified), defined by the CGI - Severity scale. CONCLUSION: Based on these results, we propose conceptual and operational definitions of response and full or partial remission in BDD. A consensus regarding these constructs will improve the interpretation and comparison of future clinical trials, as well as improve communication among researchers, clinicians, and patients. Further research is needed, especially regarding definitions of full remission, recovery, and relapse.

The Role of Paternal Accommodation of Paediatric OCD Symptoms: Patterns and Implications for Treatment Outcomes.

Family accommodation (FA) refers to the participation of family members in obsessive-compulsive disorder (OCD) rituals. Most studies have focused on maternal accommodation; consequently, little is known about fathers' accommodation of OCD. The current study aims to extend the existing literature by examining maternal versus paternal accommodation of OCD symptoms.The sample consisted of 209 children with OCD (Mean [M] age = 14.1 years) and their parents (NMothers = 209, NFathers = 209) who had completed the Family Accommodation Scale- Parent Report (FAS-PR). Paired t-test and chi-square analyses were used to compare FA of OCD symptoms between mothers and fathers. Linear regression was used to examine correlates of maternal and paternal FA and its impact on treatment outcomes.Mothers reported significantly higher levels of daily FA than fathers. Correlates of maternal and paternal accommodation included OCD symptom severity, emotional and behavioral difficulties, and parent psychopathology. Both maternal and paternal FA significantly predicted worse treatment outcomes.Both mothers and fathers accommodate child OCD symptoms with high frequency, and in similar ways. Although mothers accommodate to a greater extent than fathers, both maternal and paternal involvement in rituals are a significant predictor of the child's treatment response. Results emphasise the need to consider the whole family system, including fathers, in understanding and treating OCD in children.

Changes in Dosing and Dose Timing of D-Cycloserine Explain Its Apparent Declining Efficacy for Augmenting Exposure Therapy for Anxiety-related Disorders: An Individual Participant-data Meta-analysis.

The apparent efficacy of d-cycloserine (DCS) for enhancing exposure treatment for anxiety disorders appears to have declined over the past 14 years. We examined whether variations in how DCS has been administered can account for this "declining effect". We also investigated the association between DCS administration characteristics and treatment outcome to find optimal dosing parameters. We conducted a secondary analysis of individual participant data obtained from 1047 participants in 21 studies testing the efficacy of DCS-augmented exposure treatments. Different outcome measures in different studies were harmonized to a 0-100 scale. Intent-to-treat analyses showed that, in participants randomized to DCS augmentation (n = 523), fewer DCS doses, later timing of DCS dose, and lower baseline severity appear to account for this decline effect. More DCS doses were related to better outcomes, but this advantage leveled-off at nine doses. Administering DCS more than 60 minutes before exposures was also related to better outcomes. These predictors were not significant in the placebo arm (n = 521). Results suggested that optimal DCS administration could increase pre-to-follow-up DCS effect size by 50%. In conclusion, the apparent declining effectiveness of DCS over time may be accounted for by how it has been administered. Optimal DCS administration may substantially improve outcomes. Registration: The analysis plan for this manuscript was registered on Open Science Framework (https://osf.io/c39p8/).

Prevalence and heritability of body dysmorphic symptoms in adolescents and young adults: a population-based nationwide twin study.

BACKGROUND: Body dysmorphic disorder (BDD) usually begins during adolescence but little is known about the prevalence, etiology, and patterns of comorbidity in this age group. We investigated the prevalence of BDD symptoms in adolescents and young adults. We also report on the relative importance of genetic and environmental influences on BDD symptoms, and the risk for co-existing psychopathology. METHODS: Prevalence of BDD symptoms was determined by a validated cut-off on the Dysmorphic Concerns Questionnaire (DCQ) in three population-based twin cohorts at ages 15 (n = 6968), 18 (n = 3738), and 20-28 (n = 4671). Heritability analysis was performed using univariate model-fitting for the DCQ. The risk for co-existing psychopathology was expressed as odds ratios (OR). RESULTS: The prevalence of clinically significant BDD symptoms was estimated to be between 1 and 2% in the different cohorts, with a significantly higher prevalence in females (1.3-3.3%) than in males (0.2-0.6%). The heritability of body dysmorphic concerns was estimated to be 49% (95% CI 38-54%) at age 15, 39% (95% CI 30-46) at age 18, and 37% (95% CI 29-42) at ages 20-28, with the remaining variance being due to non-shared environment. ORs for co-existing neuropsychiatric and alcohol-related problems ranged from 2.3 to 13.2. CONCLUSIONS: Clinically significant BDD symptoms are relatively common in adolescence and young adulthood, particularly in females. The low occurrence of BDD symptoms in adolescent boys may indicate sex differences in age of onset and/or etiological mechanisms. BDD symptoms are moderately heritable in young people and associated with an increased risk for co-existing neuropsychiatric and alcohol-related problems.

Long-Term Outcomes of Cognitive-Behavioral Therapy for Adolescent Body Dysmorphic Disorder.

Emerging evidence suggests that cognitive-behavioral therapy (CBT) is an efficacious treatment for adolescent body dysmorphic disorder (BDD) in the short term, but longer-term outcomes remain unknown. The current study aimed to follow up a group of adolescents who had originally participated in a randomized controlled trial of CBT for BDD to determine whether treatment gains were maintained. Twenty-six adolescents (mean age = 16.2, SD = 1.6) with a primary diagnosis of BDD received a course of developmentally tailored CBT and were followed up over 12 months. Participants were assessed at baseline, midtreatment, posttreatment, 2-, 6-, and 12-month follow-up. The primary outcome measure was the clinician-rated Yale-Brown Obsessive-Compulsive Scale Modified for BDD. Secondary outcomes included measures of insight, depression, quality of life, and global functioning. BDD symptoms decreased significantly from pre- to posttreatment and remained stable over the 12-month follow-up. At this time point, 50% of participants were classified as responders and 23% as remitters. Participants remained significantly improved on all secondary outcomes at 12-month follow-up. Neither baseline insight nor baseline depression predicted long-term outcomes. The positive effects of CBT appear to be durable up to 12-month follow-up. However, the majority of patients remained symptomatic and vulnerable to a range of risks at 12-month follow-up, indicating that longer-term monitoring is advisable in this population. Future research should focus on enhancing the efficacy of CBT in order to improve long-term outcomes.

D-Cycloserine Augmentation of Exposure-Based Cognitive Behavior Therapy for Anxiety, Obsessive-Compulsive, and Posttraumatic Stress Disorders: A Systematic Review and Meta-analysis of Individual Participant Data.

Importance: Whether and under which conditions D-cycloserine (DCS) augments the effects of exposure-based cognitive behavior therapy for anxiety, obsessive-compulsive, and posttraumatic stress disorders is unclear. Objective: To clarify whether DCS is superior to placebo in augmenting the effects of cognitive behavior therapy for anxiety, obsessive-compulsive, and posttraumatic stress disorders and to evaluate whether antidepressants interact with DCS and the effect of potential moderating variables. Data Sources: PubMed, EMBASE, and PsycINFO were searched from inception to February 10, 2016. Reference lists of previous reviews and meta-analyses and reports of randomized clinical trials were also checked. Study Selection: Studies were eligible for inclusion if they were (1) double-blind randomized clinical trials of DCS as an augmentation strategy for exposure-based cognitive behavior therapy and (2) conducted in humans diagnosed as having specific phobia, social anxiety disorder, panic disorder with or without agoraphobia, obsessive-compulsive disorder, or posttraumatic stress disorder. Data Extraction and Synthesis: Raw data were obtained from the authors and quality controlled. Data were ranked to ensure a consistent metric across studies (score range, 0-100). We used a 3-level multilevel model nesting repeated measures of outcomes within participants, who were nested within studies. Results: Individual participant data were obtained for 21 of 22 eligible trials, representing 1047 of 1073 eligible participants. When controlling for antidepressant use, participants receiving DCS showed greater improvement from pretreatment to posttreatment (mean difference, -3.62; 95% CI, -0.81 to -6.43; P = .01; d = -0.25) but not from pretreatment to midtreatment (mean difference, -1.66; 95% CI, -4.92 to 1.60; P = .32; d = -0.14) or from pretreatment to follow-up (mean difference, -2.98, 95% CI, -5.99 to 0.03; P = .05; d = -0.19). Additional analyses showed that participants assigned to DCS were associated with lower symptom severity than those assigned to placebo at posttreatment and at follow-up. Antidepressants did not moderate the effects of DCS. None of the prespecified patient-level or study-level moderators was associated with outcomes. Conclusions and Relevance: D-cycloserine is associated with a small augmentation effect on exposure-based therapy. This effect is not moderated by the concurrent use of antidepressants. Further research is needed to identify patient and/or therapy characteristics associated with DCS response.

A critical review of cosmetic treatment outcomes in body dysmorphic disorder.

A high proportion of individuals with body dysmorphic disorder (BDD) undergo cosmetic treatments in an attempt to 'fix' perceived defect/s in their physical appearance. Despite the frequency with which such procedures are sought, few studies have prospectively examined the outcomes of cosmetic procedures in individuals with BDD. This article aims to critically review the literature and discuss the current debate that exists on outcomes of cosmetic treatment for individuals with BDD. An emerging literature suggests the majority of individuals with BDD have poor outcomes after cosmetic interventions; however, based on the current literature, it cannot be fully ruled out that certain individuals with mild BDD and localised appearance concerns may benefit from these interventions. Gaps in the current literature are highlighted, alongside recommendations for future research. Carefully conducted longitudinal studies with well-characterised patient populations are needed.

Understanding the covariation of tics, attention-deficit/hyperactivity, and obsessive-compulsive symptoms: A population-based adult twin study.

Chronic tic disorders (TD), attention-deficit/hyperactivity-disorder (ADHD), and obsessive-compulsive disorder (OCD) frequently co-occur in clinical and epidemiological samples. Family studies have found evidence of shared familial transmission between TD and OCD, whereas the familial association between these disorders and ADHD is less clear. This study aimed to investigate to what extent liability of tics, attention-deficit/hyperactivity, and obsessive-compulsive symptoms is caused by shared or distinct genetic or environmental influences, in a large population-representative sample of Swedish adult twins (n = 21,911). Tics, attention-deficit/hyperactivity, and obsessive-compulsive symptoms showed modest, but significant covariation. Model fitting suggested a latent liability factor underlying the three phenotypes. This common factor was relatively heritable, and explained significantly less of the variance of attention-deficit/hyperactivity symptom liability. The majority of genetic variance was specific rather than shared. The greatest proportion of total variance in liability of tics, attention-deficit/hyperactivity, and obsessive-compulsive symptoms was attributed to specific non-shared environmental influences. Our findings suggest that the co-occurrence of tics and obsessive-compulsive symptoms, and to a lesser extent attention-deficit/hyperactivity symptoms, can be partly explained by shared etiological influences. However, these phenotypes do not appear to be alternative expressions of the same underlying genetic liability. Further research examining sub-dimensions of these phenotypes may serve to further clarify the association between these disorders and identify more genetically homogenous symptom subtypes. © 2016 Wiley Periodicals, Inc.

A Pilot Randomized Controlled Trial of Cognitive-Behavioral Therapy for Adolescents With Body Dysmorphic Disorder.

OBJECTIVE: Body dysmorphic disorder (BDD) typically starts in adolescence, but evidence-based treatments are yet to be developed and formally evaluated in this age group. We designed an age-appropriate cognitive-behavioral therapy (CBT) protocol for adolescents with BDD and evaluated its acceptability and efficacy in a pilot randomized controlled trial. METHOD: Thirty adolescents aged 12 to 18 years (mean = 16.0, SD = 1.7) with a primary diagnosis of BDD, together with their families, were randomly assigned to 14 sessions of CBT delivered over 4 months or a control condition of equivalent duration, consisting of written psycho-education materials and weekly telephone monitoring. Blinded evaluators assessed participants at baseline, midtreatment, posttreatment, and at 2-month follow-up. The primary outcome measure was the Yale-Brown Obsessive-Compulsive Scale Modified for BDD, Adolescent Version (mean baseline score = 37.13, SD = 4.98, range = 24-43). RESULTS: The CBT group showed a significantly greater improvement than the control group, both at posttreatment (time × group interaction coefficient [95% CI] = -11.26 [-17.22 to -5.31]; p = .000) and at 2-month follow-up (time × group interaction coefficient [95% CI] = -9.62 [-15.74 to -3.51]; p = .002). Six participants (40%) in the CBT group and 1 participant (6.7%) in the control condition were classified as responders at both time points (χ(2) = 4.658, p = .031). Improvements were also seen on secondary measures, including insight, depression, and quality of life at posttreatment. Both patients and their families deemed the treatment as highly acceptable. CONCLUSION: Developmentally tailored CBT is a promising intervention for young people with BDD, although there is significant room for improvement. Further clinical trials incorporating lessons learned in this pilot study and comparing CBT and pharmacological therapies, as well as their combination, are warranted. CLINICAL TRIAL REGISTRATION INFORMATION: Cognitive-Behaviour Therapy for Adolescents With Body Dysmorphic Disorder; http://www.isrctn.com/; ISRCTN67699666.

EFFECTS OF HOMEWORK COMPLIANCE ON COGNITIVE-BEHAVIORAL THERAPY WITH D-CYCLOSERINE AUGMENTATION FOR CHILDREN WITH OBSESSIVE COMPULSIVE DISORDER.

BACKGROUND: The present study examined the effects of homework compliance on outcome from cognitive behavioral therapy (CBT) for children with obsessive-compulsive disorder (OCD) and the extent to which these effects differ as a function of augmentation of CBT with D-cycloserine (DCS). METHODS: Twenty-seven youth with OCD were randomized to either 50 mg DCS or placebo (PBO) administered immediately after each of 10 CBT sessions, primarily consisting of exposure and ritual prevention (ERP). Independent evaluators assessed OCD severity using the Children's Yale-Brown Obsessive-Compulsive Scale (CY-BOCS) at the start of each session. Compliance with between-session ERP assignments was also assessed at the start of each session using the Patient ERP Adherence Scale (PEAS). RESULTS: Greater homework compliance between the previous session and the current session was related to lower CY-BOCS at the current session. However, the relation between homework compliance and CY-BOCS varied by treatment condition. Higher homework compliance was related to lower CY-BOCS for participants in the DCS condition, but not for participants in the PBO condition. Furthermore, participants receiving DCS were estimated to have significantly lower CY-BOCS than those given PBO among those with the highest levels of homework compliance. CONCLUSIONS: DCS may more effectively facilitate the effects of CBT for youth with OCD when patients are compliant with prescribed homework. Theoretical and clinical implications are discussed.

Cognitive-behavioural therapy with post-session D-cycloserine augmentation for paediatric obsessive-compulsive disorder: pilot randomised controlled trial.

A partial N-methyl-D-aspartate agonist, D-cycloserine, enhances fear extinction when given before or shortly after exposure to feared stimuli in animals. In this pilot double-blind placebo-controlled trial (trial number: ISRCTN70977225), 27 youth with obsessive-compulsive disorder were randomised to either 50 mg D-cycloserine or placebo administered immediately after each of ten cognitive-behavioural therapy (CBT) sessions, primarily consisting of exposure and ritual prevention. Both groups improved significantly and maintained their gains at 1-year follow-up, with no significant advantage of D-cycloserine over placebo at any time point. The effects of CBT may not be augmented or accelerated when D-cycloserine is administered after sessions.

The structure of genetic and environmental risk factors for dimensional representations of DSM-5 obsessive-compulsive spectrum disorders.

IMPORTANCE: The new DSM-5 "Obsessive-Compulsive and Related Disorders" chapter contains a series of conditions thought to be etiologically related to obsessive-compulsive disorder (OCD). However, the evidence to support this relatedness remains incomplete. OBJECTIVE: To estimate the degree to which genetic and environmental risk factors are shared and/or unique to dimensionally scored OCD, body dysmorphic disorder (BDD), hoarding disorder (HD), trichotillomania (hair-pulling disorder) (TTM), and excoriation (skin-picking) disorder (SPD). DESIGN, SETTING, AND PARTICIPANTS: Multivariate twin modeling methods involving 5409 female members of the TwinsUK adult population-based twin register. MAIN OUTCOMES AND MEASURES: Scores on the Obsessive-Compulsive Inventory-Revised, the Dysmorphic Concern Questionnaire, the Hoarding Rating Scale, the Massachusetts General Hospital Hairpulling Scale, and the Skin Picking Scale. RESULTS: A 2-latent factor common pathway model fitted the data best; the first latent factor loaded on all 5 phenotypes, particularly on OCD, BDD, and HD. A second factor loaded exclusively on TTM and SPD. Disorder-specific genetic (for OCD, BDD, and HD only) and particularly nonshared environmental risk factors were also evident. Shared environmental influences were negligible. CONCLUSIONS AND RELEVANCE: Obsessive-compulsive and related disorders may be influenced by 2 distinct liability factors rather than a single liability factor. One of these factors was common to all disorders, and another was exclusive to TTM and SPD. Disorder-specific genetic factors unique to OCD, BDD, and HD were also apparent, whereas TTM and SPD were largely influenced by the same latent genetic factor. Environmental influences were largely disorder specific. The results help explain the apparent similarities as well as some important differences between the disorders included in the new Obsessive-Compulsive and Related Disorders chapter.

Holistic versus detailed visual processing in body dysmorphic disorder: testing the inversion, composite and global precedence effects.

Individuals with Body Dysmorphic Disorder (BDD) are preoccupied with perceived defects in their appearance that are not visible to others. An excessive focus and processing of details has been proposed as a possible mechanism underlying this distorted self-image in BDD. The nature and extent of visuoperceptual abnormalities in BDD however require further investigation; specifically, it remains unclear whether feature-based processing in BDD is a result of a failure of holistic perceptual processes. The present study evaluated whether BDD is associated with an impairment in global processing. Twenty-five individuals with a primary diagnosis of BDD (15 unmedicated, 10 medicated) and 25 matched healthy controls were administered three robust behavioural tasks that test holistic encoding, namely the face inversion, the composite and the navon tasks. Overall, individuals in the BDD and control groups performed similarly in all aspects of holistic processing tested. Our findings suggest that the excessive focus on specific aspects of appearance in BDD may not be explained by impairments in the global encoding of visual information. Implications of these results and suggestions for future research on visual processing in BDD are discussed.

Population-based, multigenerational family clustering study of obsessive-compulsive disorder.

IMPORTANCE: Controlled family studies have consistently found that obsessive-compulsive disorder (OCD) aggregates in families but have typically relied on samples recruited from specialist clinics. Furthermore, previous studies could not disentangle genetic from environmental factors contributing to the observed familiality. OBJECTIVE: To provide unbiased estimates of familial risk for and heritability of OCD at the population level. DESIGN AND SETTING: Population-based, multigenerational, case-control family and twin studies using the Swedish National Patient Register, Multi-Generation Register, and Twin Register. PARTICIPANTS: All individuals diagnosed as having OCD between January 1, 1969, and December 31, 2009 (n = 24 768) and all their available first-, second-, and third-degree relatives, as well as nonbiological relatives and matched general population control subjects. Twins (n = 16 383) were included from the population-based Twin Register. MAIN OUTCOME AND MEASURE: The risk for OCD among relatives of OCD probands. RESULTS: The risk for OCD among relatives of OCD probands increased proportionally to the degree of genetic relatedness. The risk for first-degree relatives was significantly higher than that for second- and third-degree and nonbiological relatives. Second-degree relatives had higher risk for OCD than third-degree relatives. Relatives at similar genetic distances had similar risks for OCD, despite different degrees of shared environment. Separate twin modeling analyses confirmed that familial risk for OCD was largely attributable to additive genetic factors (47%; 95% CI, 42%-52%), with no significant effect of shared environment. Nonbiological relatives (spouses or partners who have at least 1 child together) also had an elevated risk for OCD (odds ratio, 2.61; 95% CI, 1.99-3.42). Early-onset probands (3907 individuals; mean age, 13.7 years) had slightly (nonsignificantly) higher familial risk than the total sample, although this was substantially lower than previously reported. There were no significant sex differences in the familial pattern or heritability estimates. CONCLUSIONS AND RELEVANCE: Obsessive-compulsive disorder clusters in families primarily due to genetic factors. Nonshared environmental factors are at least as important. The quest for candidate genes, nonshared environmental risk factors, and their possible correlation or interaction should continue. The finding of possible assortative mating in OCD is intriguing and should be investigated further.

Overlap and specificity of genetic and environmental influences on excessive acquisition and difficulties discarding possessions: Implications for hoarding disorder.

A reluctance to discard items, leading to severely cluttered living spaces, is the landmark feature of hoarding disorder (HD). Many, but not all, individuals with HD also excessively acquire, buy or even steal items that they do not need and for which no space is available. In DSM-5, "excessive acquisition" can be coded as a specifier of HD. Despite their consistent co-occurrence, the question of whether excessive acquisition and difficulties discarding possessions share a common etiology remains unanswered. The current study sought to flesh out this relationship by examining the extent of shared genetic and environmental influences on the association between excessive acquisition and difficulties discarding in a community sample of adult, female twins. A total of 5,022 female twins (2,529 pairs; mean age = 55.5 years) completed a self-report measure of hoarding symptoms, including items assessing excessive acquisition and difficulties discarding. The data were analyzed using bivariate twin modeling methods in the statistical program Mx. As expected, we found a strong phenotypic correlation (0.63) between excessive acquisition and difficulty discarding items. Both traits were moderately heritable. The genetic correlation between the traits was estimated to be 0.77 (95% CI: 0.69-0.85), indicating a substantial but imperfect genetic overlap. The non-shared environmental correlation (0.50 [95% CI: 0.42-0.57]), though lower, was also significant. The findings demonstrate a substantial genetic, and more modest environmental, etiological overlap between the excessive acquisition of possessions and difficulties discarding them, providing a possible explanation for their frequent co-occurrence in HD. However, given that the etiological overlap is not perfect, unique etiological influences, particularly environmental, on each phenotype seem plausible.