title: The structure of genetic and environmental risk factors for dimensional representations of DSM-5 obsessive-compulsive spectrum disorders.
abstract: OBJECTIVE
  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).
  
  
  METHODS
  Multivariate twin modeling methods involving 5409 female members of the TwinsUK adult population-based twin register.
  
  
  METHODS
  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
  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.
authors.affiliation: Department of Psychosis Studies, King's College London, Institute of Psychiatry, London, England.
authors.forename: Benedetta
authors.initials: B
authors.lastname: Monzani
authors.affiliation: Social, Genetic & Developmental Psychiatry Research Centre, King's College London, Institute of Psychiatry, London, England.
authors.forename: Fruhling
authors.initials: F
authors.lastname: Rijsdijk
authors.affiliation: Department of Twin Research and Genetic Epidemiology, King's College London School of Medicine, London, England.
authors.forename: Juliette
authors.initials: J
authors.lastname: Harris
authors.affiliation: Department of Psychosis Studies, King's College London, Institute of Psychiatry, London, England4Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
authors.forename: David
authors.initials: D
authors.lastname: Mataix-Cols
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D057215:Body Dysmorphic Disorders / Q000175:diagnosis / Q000209:etiology* / Q000235:genetics; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004200:Diseases in Twins / Q000175:diagnosis / Q000209:etiology / Q000235:genetics; D005163:Factor Analysis, Statistical; D005260:Female; D059647:Gene-Environment Interaction; D000067836:Hoarding Disorder / Q000175:diagnosis / Q000209:etiology / Q000235:genetics; D006801:Humans; D008875:Middle Aged; D009771:Obsessive-Compulsive Disorder / Q000175:diagnosis / Q000209:etiology* / Q000235:genetics; D025341:Principal Component Analysis; D012042:Registries; D012307:Risk Factors; D016728:Self-Injurious Behavior / Q000175:diagnosis / Q000209:etiology* / Q000235:genetics; D014256:Trichotillomania / Q000175:diagnosis / Q000209:etiology* / Q000235:genetics; D006113:United Kingdom; D055815:Young Adult