[Obsessive compulsive disorder. Clinical and epidemiologic studies].

Until recently, Obsessive-Compulsive Disorder (OCD) was considered rare trouble with rather poor outcome. Currently progress in behavioral psychology, psychopharmacology and methodology of epidemiologic studies multiplying by 50 the traditional prevalence rates, give an impetus to the interest in this pathology. Recent clinical and epidemiologic data in OCD are reported in this paper. Multiple questions are evoked such as the issue of OCD homogeneity, the meaning of comorbidity with other psychological disorders: depression, panic attacks, schizophrenia, Gilles de la Tourette syndrome, the reality of OCD prevalence rate in general and psychiatric populations, the usefulness of classical demarcation between psychosis/neurosis in the treatment of OCD, and finally the search for a genetic diathesis and risk factors implicated in predisposition to OCD. A close relationship between clinical, epidemiologic and genetic approaches seems to be required in order to answer these questions and constitutes a first step prior to carrying on basic and applied research.