Objective: To determine the effects of methylphenidate (MPH) and dextroamphetamine (DEX) on tic severity in boys with attention-deficit/hyperactivity disorder (ADHD) comorbid with Tourette's syndrome.
Method: A 9-week, placebo-controlled, double-blind crossover using a wide range of doses was completed by 20 subjects in three cohorts.
Results: Relatively high doses of MPH and DEX in the first cohort produced significant increases in tic severity which were sustained on higher doses of DEX but which attenuated on MPH. Overall, 14 of 20 subjects continued stimulant treatment for 1 to 3 years, generally in combination with other psychotropics. Stimulant-associated adverse effects, including tic exacerbations, were reversible in all cases.
Conclusion: A substantial minority of comorbid subjects had consistent worsening of tics on stimulants, although the majority experienced improvement in ADHD symptoms with acceptable effects on tics. MPH was better tolerated than DEX.