Principal components analysis of a large cohort with Tourette syndrome

BACKGROUND: Tourette syndrome is a heterogeneous familial disorder for which the genetic mechanisms are unknown. A better characterisation of the phenotype may help identify susceptibility genes. AIMS: To extend previous factor-analytic studies of the syndrome. METHOD: Symptom data from 410 people with Tourette syndrome were included in agglomerative hierarchical cluster and principal components analyses. RESULTS: Five factors were observed, characterised by: (1) socially inappropriate behaviours and other complex vocal tics; (2) complex motor tics; (3) simple tics; (4) compulsive behaviours; and (5) touching self. Individuals with co-occurring attention-deficit hyperactivity disorder had significantly higher factor scores on Factors 1 and 3, whereas individuals with co-occurring obsessive-compulsive disorder and behaviours had significantly higher factor scores for Factors 1-4. CONCLUSIONS: These findings add to the growing body of evidence that Tourette syndrome is not a unitary condition and can be disaggregated into more homogeneous symptom components.