Attention Deficit Hyperactivity Disorder (ADHD) is a commonly co-occurring condition among children and adolescents with TS. Indeed, in some cases, ADHD presents a more serious problem for individuals than the motor tics. The standard medications for ADHD are stimulants such as methylphenidate, d-amphetamine and pemoline. However, the use of these stimulants in the treatment of children with tics remains controversial. Although recent evidence suggests that some children with TS can tolerate treatment without an unacceptable increase in their tics, others exhibit more tics upon exposure to stimulants. Consequently, many clinicians and families are reluctant to use these medications for children with tic disorders and comorbid ADHD. The purpose of this study is to evaluate the effectiveness of another type of medication, guanfacine, in the treatment of children and adolescents with both TS and ADHD. Guanfacine is an antihypertensive medication that shares several features in common with clonidine. However, it appears to be less sedating than clonidine. In addition, guanfacine also has a longer duration of action which means that it can usually be taken in three doses per day. Recent open studies with guanfacine in children with ADHD, with and without TS, have provided promising results. To date, however, there have been no double-blind studies of this medication in children with ADHD or TS. This study consists of a double-blind phase and an open treat¬ment phase. The term double-blind means that neither the investiga¬tors nor the family are aware of which drug is being assigned. In the double-blind phase, the child is randomly assigned to receive either guanfacine or an inactive placebo. In the second phase, the child is treated with guanfacine in an open fashion. The open phase permits the clinical team and the family to evaluate the stability of treatment effects after the double-blind phase. To evaluate the effects of guanfacine, we will use teacher and parent ratings of behavior, as well as computerized tests of attention, and ratings of tic severity. When a medication is effective under double-blind conditions, these data provide persuasive evidence that the medication is indeed effective. Thus, this study will help confirm whether guanfacine is a useful medication for the treatment of children and adolescents who have both ADHD and TS. Lawrence Scahill, M.S.N., M.P.H. Yale Child Study Center New Haven, CT Robert A. King, M.D. Yale University School of Medicine New Haven, CT Award $23,966 Tourette Association of America Inc. – Research Grant Award 1996