Obsessive compulsive disorder among idiopathic focal dystonia patients: an epidemiological and family study.

BACKGROUND: A disturbed function of striato-thalamo-cortical circuitry is hypothesized to underlie idiopathic focal dystonia (IFD) and obsessive compulsive disorder (OCD), two severe and disabling neurologic and psychiatric disorders. Previous studies on small samples showed either higher obsessionality scores or higher frequency of OCD in dystonic patients than in normal control subjects. The aim of this study was to evaluate the frequency and familial loading of OCD in a population of patients with IFD. METHODS: We evaluated OCD diagnosis and family history in 76 patients affected by IFD. RESULTS: Of our subjects 19.7% satisfied DSM-IV criteria for OCD diagnosis and had a family morbidity risk for OCD of 13.8%, significantly higher than that found in the general population. CONCLUSIONS: Our results support the hypothesis of a common pathologic background for OCD and IFD, at least in a subgroup of IFD, indicating basal ganglia dysfunction.