With both MPH and AMPH, Castellanos et al. (1997) found a dose-dependent worsening of tics in a substantial minority of patients comorbid for ADHD and Tourette’s syndrome. As already noted, three discontinued medication at the conclusion of the trials due to increased tic severity on both MPH and Amph. They observed, a substantial proportion of our small sample (one third) continued to have stimulant-associated exacerbations of their tic disorder which outweighed the clinical benefits of stimulants.