Are there distinct subtypes in Tourette syndrome? Pure-Tourette syndrome versus Tourette syndrome-plus, and simple versus complex tics

Abstract

Valsamma Eapen,1,2 Mary M Robertson3,41School of Psychiatry, University of New South Wales, Sydney, NSW, Australia; 2Academic Unit of Child Psychiatry, South Western Sydney Local Health District, Ingham Institute, Liverpool, NSW, Australia; 3Neuropsychiatry, University College London, UK; 4St Georges Hospital and Medical School, London, UKAbstract: This study addressed several questions relating to the core features of Tourette syndrome (TS) including in particular coprolalia (involuntary utterance of obscene words) and copropraxia (involuntary and inappropriate rude gesturing). A cohort of 400 TS patients was investigated. We observed that coprolalia occurred in 39% of the full cohort of 400 patients and copropraxia occurred in 20% of the cohort. Those with coprolalia had significantly higher Yale Global Tic Severity Scale (YGTSS) and Diagnostic Confidence Index (DCI) total scores and a significantly higher proportion also experienced copropraxia and echolalia. A subgroup of 222 TS patients with full comorbidity data available were also compared based on whether they had pure-TS (motor and vocal tics only) or associated comorbidities and co-existent psychopathologies (TS-plus). Pure-TS and TS-plus groups were compared across a number of characteristics including TS severity, associated clinical features, and family history. In this subgroup, 13.5% had pure-TS, while the remainder had comorbidities and psychopathologies consistent with TS-plus. Thirty-nine percent of the TS-plus group displayed coprolalia, compared to (0%) of the pure-TS group and the difference in proportions was statistically significant. The only other significant difference found between the two groups was that pure-TS was associated with no family history of obsessive compulsive disorder which is an interesting finding that may suggest that additional genes or environmental factors may be at play when TS is associated with comorbidities. Finally, differences between individuals with simple versus complex vocal/motor tics were evaluated. Results indicated that individuals with complex motor/vocal tics were significantly more likely to report premonitory urges/sensations than individuals with simple tics and TS. The implications of these findings for the assessment and understanding of TS are discussed.Keywords: Tourette syndrome, comorbidity, simplex tics, complex tics