COURSE OF TIC SEVERITY IN TOURETTE-SYNDROME - THE FIRST 2 DECADES

Objective. Prevalence studies indicate a 10-fold higher rate of Touret te syndrome (TS) among children compared with adults. The purpose of t his investigation was to examine the course of tic severity during the first 2 decades of life. Method. A birth-year cohort of 42 TS patient s followed at the Yale Child Study Center was recontacted an average o f 7.3 years after their initial clinical evaluation. Data concerning t he onset and course of tic severity until 18 years of age were availab le on 36 TS patients. A variety of statistical techniques were used to model aspects of the temporal patterning of tic severity. Results. Me an (SD) tic onset at 5.6 (2.3) years of age was followed by a progress ive pattern of tic worsening. On average, the most severe period of ti e severity occurred at 10.0 (2.4) years of age. In eight cases (22%), the frequency and forcefulness of the ties reached a severe level duri ng the worst-ever period such that functioning in school was impossibl e or in serious jeopardy. In almost every case this period was followe d by a steady decline in tic severity. By 18 years of age nearly half of the cohort was virtually tie-free. The onset of puberty was not ass ociated with either the timing or severity of ties. Conclusions. A maj ority of TS patients displayed a consistent time course of tic severit y. This consistency can be accurately modeled mathematically and may r eflect normal neurobiological processes. Determination of the model pa rameters that describe each patient's course of tic severity may be of prognostic value and assist in the identification of factors that dif ferentially influence the course of tic severity.