In all of the studies in which all available relatives of children and/or adolescents with OCD were interviewed,40-41,61-65 the rates of OCD and subclinical OCD were significantly higher than the population prevalence and/or the rate obtained in controls assessed in the same way. While the frequency of OCD and subclinical OCD differed within families across studies, the overall conclusion was the same: OCD and subclinical OCD are familial. Furthermore, the recurrence risks within these families were considerably higher than the rates observed in families ascertained through adults (see below). While the rate of OCD among relatives of adults with OCD was approximately two times that among controls, the rate of OCD among relatives of children and adolescents with OCD was increased approximately 10-fold in those studies where comparison with controls was possible.
