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Does Long-Term MPH Treatment Worsen Tics?

How to medicate children with comorbid attention-deficit hyperactivity disorder (ADHD) and chronic multiple tic disorder has been a clinical challenge. Medications used for ADHD, such as methylphenidate (MPH), block the dopamine transporter, thus increasing the availability of dopamine at receptors. MPH was thought to exacerbate tics, although clinical evidence was lacking; however, recent studies showed that MPH did not worsen tics in children comorbid for the two disorders. This follow-up of one study sheds further light on this issue.

Thirty-four children (mean age, 10.8) were nonblindedly reassessed on a comprehensive battery at six-month intervals for two years. On all but a few measures, tics did not worsen, even though the mean dose of MPH increased from 16.5 mg to 34.5 mg. Heart rate increased a mean of 10 beats per minute (of controversial clinical significance), but there were no other clinically significant side effects.

Comment: As the authors point out, the generalizability of findings may be limited by the small number of subjects, and findings may be confounded by individual variations in the natural course of tic disorders. In Tourette's syndrome, tic severity is known to wax and wane, and symptoms may peak at ages 10 to 11 years (i.e., during the follow-up phase of this study). Lack of blindedness is also an issue. However, these findings are important because ADHD is often the more clinically problematic of the two conditions in comorbid children.

— B Geller

Published in Journal Watch Psychiatry June 1, 1999

Citation(s):

Gadow KD et al. Long-term methylphenidate therapy in children with comorbid attention-deficit hyperactivity disorder and chronic tic disorder. Arch Gen Psychiatry 1999 Apr 56 330-336.

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