The efficacy of deprenyl, a monoamine oxidase inhibitor, was evaluated in the treatment of ADHD in 24 children and adolescents with comorbid Tourette’s syndrome (TS) enrolled at the University of Rochester and Baylor College of Medicine. A double-blind placebo-controlled crossover design included two 8-week treatment periods separated by a 6-week washout period. A beneficial effect of deprenyl on tics was noted, but improvement of ADHD symptoms was limited to the first treatment period. 
COMMENT. Deprenyl is metabolized to amphetamine and methamphetamine. By inhibiting breakdown of dopamine and increasing synaptic dopamine levels, deprenyl might be expected to worsen tics. These authors report a controlling effect on tics, possibly due to an influence on dopamine receptors. The failure to demonstrate a significant beneficial effect on ADHD could be explained by the crossover study design and patient dropout.