Patterns of obsessive compulsive symptoms in Tourette subjects are independent of severity

Studies have examined the expression of obsessive compulsive (OC) symptoms in obsessive compulsive disorder (OCD), OCD with co-occurring Tourette's Syndrome (TS) or chronic motor tic disorder (CMT) and TS alone. In adult samples, there appears to be a relatively consistent OC symptom thematic content that characterizes OCD alone and OCD in conjunction with tics or TS. Previous studies have controlled for the severity of OC symptoms in OCD and TS groups. In the current study, it was our objective to determine whether patterns of OC symptoms in TS are independent of OC symptom severity. The current exploratory study examined OC symptom expression in a nonclinically based TS sample with a broad range of OC symptoms and severity and a selected clinical OCD sample without TS/tics. Univariate and multivariate statistical analysis explored patterns of OC symptom expression between the two groups. Similar to previous reports examining OC symptoms in OCD and OCD with TS/tics, subjects with OCD alone were characterized by contamination obsessions and cleaning compulsions. In contrast, TS subjects had more somatic, sexual and symmetry obsessions and more checking, counting and touching/blinking compulsions, independent of OC symptom and tic severity. A discriminant function using obsessive items alone correctly grouped 91.4% of cases. The current study replicates patterns of OC symptom expression unique to OCD alone. Patterns of OC symptoms, in particular obsessive symptoms, can robustly predict membership in OCD or TS groups, even with a substantial variation in OC symptom severity as measured by the Y-BOCS score.