Fine-motor skill deficits in childhood predict adulthood tic severity and global psychosocial functioning in Tourette's syndrome

Background: Most children with Tourette's syndrome (TS) experience a significant decline in tic symptoms during adolescence. Currently no clinical measures have been identified that can predict whose tic symptoms will persist into adulthood. Patients with TS have deficits on neuropsychological tests involving fine-motor coordination and visual-motor integration. We seek to determine if these neuropsychological tests are useful in predicting future symptom severity. Methods: Thirty-two children, aged 8 - 14, with TS underwent clinical evaluation and a focused neuropsychological testing battery consisting of the Purdue Pegboard, Beery Visual-Motor Integration (VMI) Test and the Rey-Osterreith Complex Figure Task (RCFT). A follow-up clinical assessment was performed on these children an average of 7.5 years later. Ordinal logistic regression analysis was used to correlate neuropsychological testing at Time 1 with tic severity, OCD severity and global psychosocial functioning at Time 2. Results: Poor performance with the dominant hand on the Purdue Pegboard test predicted worse adulthood tic severity and correlated with tic severity at the time of childhood assessment. Poor performance on the VMI and Purdue Pegboard tests (both dominant and non-dominant hand) also predicted worse adulthood global psychosocial functioning. None of the neuropsychological tests were useful in predicting the future course of OCD symptoms in TS patients. Conclusion: Fine motor skill deficits may be a predictor of future tic severity and global psychosocial function in children with TS. We hypothesize that performance on the Purdue Pegboard test may serve as a useful endophenotype in the study of TS and provide a rough measure of the degree of basal ganglia dysfunction present in TS patients.