Non-drug interventions for TS (e.g., habit reversal training; HRT) teach people techniques that may help to control (i.e., suppress) their tics. However, voluntary tic suppression may have unwanted behavioral side effects including a “rebound effect” in which tic frequency, after a period of voluntary suppression, temporarily increases to levels greater than baseline. If this is true, it would suggest that we should be cautious in our approaches and use of non-drug therapies for TS. While many professionals assume that the rebound effect occurs, very little research has been done. It is unclear what enhances a person’s ability to voluntarily suppress tics, and if a rebound effect occurs, the behavioral factors that create or prevent this effect are unknown. Our study will be coordinated by the University of Wisconsin-Milwaukee, and data will be collected at North Dakota State (Fargo, ND) and Western Michigan (Kalamazoo/Grand Rapids, MI) Universities. Our objectives are first to evaluate the effects of voluntary tic suppression on the frequency and severity of motor and vocal tics after three durations of tic suppression (5 min, 25 min, and 50 min). We hypothesize that tic suppression may lead to a temporary rebound effect that will increase as the duration of suppression lengthens. Second, we propose to identify variables that predict an individual’s ability to suppress tics. It is expected that increased tic severity, decreased response inhibition, and deficits in working memory will reduce the ability to suppress symptoms. Our results will allow us to determine the presence or absence of a rebound effect, and whether it is more likely to occur as periods of suppression increase. Likewise, results may inform us on neuropsychological factors that would predict tic suppression or rebound effects. Our findings will be informative in the development and modification of non-pharmacological interventions for TS, and will aid in the understanding of tic suppression and its effects. Douglas W. Woods, Ph.D. University of Wisconsin, Milwaukee, WI Award: $21,284 In loving memory of Virginia Graeme Baker Tourette Association of America Inc. – Research Grant Award 2004-2005