The familial phenotype of obsessive-compulsive disorder in relation to tic disorders: the Hopkins OCD family study
Authors
Marco A Grados ; Mark A Riddle ; Jack F Samuels ; Kung-Yee Liang ; Rudolf Hoehn-Saric ; O.Joseph Bienvenu ; John T Walkup ; DongHo Song ; Gerald Nestadt
Family study ; obsessive-compulsive disorder ; tic disorders ; Tourette’s syndrome
Abstract
Background: Obsessive-compulsive disorder (OCD) and tic disorders have phenomenological and familial-genetic overlaps. An OCD family study sample that excludes Tourette’s syndrome in probands is used to examine whether tic disorders are part of the familial phenotype of OCD.
Methods: Eighty case and 73 control probands and their first-degree relatives were examined by experienced clinicians using the Schedule for Affective Disorders and Schizophrenia-Lifetime Anxiety version. DSM-IV psychiatric diagnoses were ascertained by a best-estimate consensus procedure. The prevalence and severity of tic disorders, age-at-onset of OCD symptoms, and transmission of OCD and tic disorders by characteristics and type of proband (OCD + tic disorder, OCD − tic disorder) were examined in relatives.
Results: Case probands and case relatives had a greater lifetime prevalence of tic disorders compared to control subjects. Tic disorders spanning a wide severity range were seen in case relatives; only mild severity was seen in control relatives. Younger age-at-onset of OCD symptoms and possibly male gender in case probands were associated with increased tic disorders in relatives. Although relatives of OCD + tic disorder and OCD − tic disorder probands had similar prevalences of tic disorders, this result is not conclusive.
Conclusions: Tic disorders constitute an alternate expression of the familial OCD phenotype.