Epidemiology and Genetics of OCD: A Review and Discussion of Future Directions for Research

Abstract

AbstractThe author reviews both the epidemiology and the genetics of obsessive-compulsive disorder (OCD). A relatively common disorder, OCD has an onset in late adolescence or early adulthood. Its gender distribution is nearly equal, although women are slightly more likely to develop the disorder. Usually chronic, OCD fluctuates depending on factors including the presence of depressed mood or stressful life events. OCD is associated with substantial psychiatric comorbidity, it affects quality of life, and it affects health care utilization. Many questions remain unanswered, such as whether its natural history has changed with the advent of effective therapies, and to what extent patients with OCD are disabled.There are no adoption studies of OCD, but reports of twins suggest greater monozygotic than dizygotic concordance. Family study results are not entirely consistent, probably because of differences in study methods, but tend to show that OCD is familial. They also show a genetic relationship to subclinical OCD and Tourette's syndrome. Molecular genetic studies are just getting under way. Important issues remain to be answered, including defining the extent of an OCD spectrum of disorders, and determining what constitutes an OCD phenotype.The author concludes by recommending that further studies on OCD involve samples from the general population rather than clinic- or hospital-based samples, which are inherently biased for severity.The past 15 years have been exciting for psychiatric researchers interested in the epidemiology and genetics of OCD. Combined with ongoing development of effective pharmacologic and behavioral treatments, new research in these areas has affected how physicians think about OCD, as well as how we clinically manage patients. More work needs to be done, as many important questions about both the epidemiology and genetics of OCD remain unanswered.