Variables associated with increased Tic severity in 5,500 participants with Tourette syndrome

Objective: Tourette syndrome (TS) is a common developmental disorder with childhood onset. This study utilizes the TIC consortium data to develop models of variables associated with increased severity of tics in people with TS. The TIC database comprised 5,500 people with TS. Method: This study included the 5,450 participants with clinician reported severity of tics (mild, moderate, or severe). We developed 3 models of tic severity. Results: Model 1 comprised age of diagnosis and total number of comorbidities and correctly classified 71% of mild-moderate cases, 46% of severe, and 68% of the total group. Model 2 comprised 7 of 21 comorbid conditions and classified 78% of mild-moderate cases, 53% of severe cases, and 74% of the total population. Model 3 comprised 6 comorbid conditions and correctly classified 75% of mild-moderate cases, 57% of severe cases, and 72% of the total cohort. We found the attention-deficit hyperactivity disorder was not associated with tic severity but obsessive compulsive disorder was an important variable associated with tic severity. Conclusion: This large dataset provides 3 models of variables associated with increased tic severity at the time of diagnosis. Further research is needed to identify factors associated with longitudinal changes in tic severity. This should include factors that are associated with both increased and decreased severity.