a1 Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
a2 Department of Biostatistics, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA
a3 Department of Psychiatry and Human Behavior, Brown Medical School, Providence, RI, USA
a4 Columbia University College of Physicians and Surgeons, New York, NY, USA
a5 New York State Psychiatric Institute, New York, NY, USA
a6 Massachusetts General Hospital, Boston, MA, USA
a7 Harvard Medical School, Department of Psychiatry, Boston, MA, USA
a8 Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles School of Medicine, Los Angeles, CA, USA
a9 Laboratory of Clinical Science, National Institute of Mental Health, Bethesda, MD, USA
a10 Department of Psychiatry and Behavioral Sciences, Keck School of Medicine at the University of Southern California, Los Angeles, CA, USA
Background Experts have proposed removing obsessive–compulsive disorder (OCD) from the anxiety disorders section and grouping it with putatively related conditions in DSM-5. The current study uses co-morbidity and familiality data to inform these issues.
Method Case family data from the OCD Collaborative Genetics Study (382 OCD-affected probands and 974 of their first-degree relatives) were compared with control family data from the Johns Hopkins OCD Family Study (73 non-OCD-affected probands and 233 of their first-degree relatives).
Results Anxiety disorders (especially agoraphobia and generalized anxiety disorder), cluster C personality disorders (especially obsessive–compulsive and avoidant), tic disorders, somatoform disorders (hypochondriasis and body dysmorphic disorder), grooming disorders (especially trichotillomania and pathological skin picking) and mood disorders (especially unipolar depressive disorders) were more common in case than control probands; however, the prevalences of eating disorders (anorexia and bulimia nervosa), other impulse-control disorders (pathological gambling, pyromania, kleptomania) and substance dependence (alcohol or drug) did not differ between the groups. The same general pattern was evident in relatives of case versus control probands. Results in relatives did not differ markedly when adjusted for demographic variables and proband diagnosis of the same disorder, though the strength of associations was lower when adjusted for OCD in relatives. Nevertheless, several anxiety, depressive and putative OCD-related conditions remained significantly more common in case than control relatives when adjusting for all of these variables simultaneously.
Conclusions On the basis of co-morbidity and familiality, OCD appears related both to anxiety disorders and to some conditions currently classified in other sections of DSM-IV.
(Received September 24 2010)
(Revised April 06 2011)
(Accepted April 09 2011)
(Online publication May 13 2011)