Objective: The aim of this study was to assess whether weekend drug holidays during methylphenidate (MPH) administration would change the efficacy and tolerability to the medication in male children with Attention-Deficit Hyperactivity Disorder (ADHD).
Methods: In a 28-day, double-blind study, children with diagnoses of ADHD were randomized to receive BID MPH for 7 days a week (n = 21) or to receive BID MPH on weekdays and a placebo on weekends (n = 19). Parents completed the Conners' Abbreviated Rating Scale (ABRS) to assess ADHD symptoms and the Barkley's Side Effect Rating Scale (SERS) to assess side effects on weekends. Teachers completed the ABRS on each Monday after weekends.
Results: Both groups showed a significant reduction on the ABRS over time as the dose was increased. However, the group difference in the ABRS scores was not statistically significant, either on weekend parent ratings (at the endpoint, p = 0.41; effect size = 0.26) or on teachers' ratings (at the endpoint, p = 0.99; effect size = 0.002). The omission of MPH on weekends was associated with significantly less severity of insomnia (F = 3.96, d.f. = 1, p = 0.05) and a trend for less interference on appetite (F = 3.18, d. f. = 1, p = 0.08).
Conclusion: Our findings suggest that weekend holidays during MPH administration reduce the side effects of insomnia and appetite suppression without a significant increase in symptoms, either on weekends or in the first school day after them. Possible explanations for these findings (rate-dependent response or impact of demands of the environment) are discussed in this paper.