Obsessive-compulsive disorder (OCD) may represent a syndrome with multiple aetiologies rather than a homogeneous disease entity. One putative subgroup of OCD is composed of those OCD patients with a lifetime history of tic symptoms (Tourette's syndrome

Abstract

Obsessive-compulsive disorder (OCD) may represent a syndrome with multiple aetiologies rather than a homogeneous disease entity. One putative subgroup of OCD is composed of those OCD patients with a lifetime history of tic symptoms (Tourette's syndrome (TS) or chronic motor or vocal tic disorder). Various studies examining familial, clinical descriptive, and neuropharmacological data suggest an association between obsessive-compulsive(OC) and tic symptoms. Compared with the general population, OC symp toms are much more prevalent among TS patients (Pauls et al, 1986), and a higher proportion of OCD patients and their first-degree relatives have a lifetime history of tic symptoms (Pauls, 1990). Consistent with this, Pitman et a! (1987) also found a high rate of tic symptoms in OCD patients and their relatives, and noted that tics were more useful in distinguishing relatives of OCD patients from relatives of controls than were obsessions or compulsions. In a recent family study of 100 OCD probands (Pauls et al, 1993, unpublished), approximately 10% of their first-degree relatives met criteria for TS. Additional support for an association between OCD and TS comes from brain imaging studies (Baxter eta!, 1990) and case reports of striatal injury (LaPlane et al, 1989), which implicate the basal ganglia and related structures as the possible neuroanatomic loci of both OCD and TS. Furthermore, some treatment response data suggest that tic history may identify a subgroup of otherwise treatment-resistant patients with OCD (McDougle et al, 1993) who respond favourably to a combination of a serotonin re-uptake inhibitor and a dopamine antagonist (McDougle et al, 1990). To explore further the heterogeneity of OCD, patients with OCD, with and without a lifetime history of a chronic tic disorder, were examined with respect to specific types of OC symptoms using the symptom checklist of the Yale—BrownObsessive Compulsive Scale (YBOCS) (Goodman eta!, 1989). The main objective was to identify a set of OC symptoms that could distinguish between these two putative subtypes of OCD.