Background: This study examined short-term efficacy, side effects and acceptability of a placebo treatment procedure designed to maintain children with attention deficit hyperactivity disorder (ADHD) on 50% of their usual stimulant dose.
Methods: An open-label prospective crossover trial was conducted in 26 children with ADHD, ages 7-15 years, stable on stimulant therapy, followed at a community-based developmental paediatrics ADHD clinic. Subjects were randomly assigned to one of two orders of experimental conditions: (1) baseline (100%) dose (1 week), then 50% dose (1 week), then 50% dose + placebo (1 week), or (2) baseline (100%), then 50% dose + placebo, then 50% dose. The inert nature of the placebo was fully disclosed to parent and child. Treatment was open-label for child, parents and physician, but single blind for teachers. Main outcome measures included weekly IOWA Conners parent and teacher rating scales, the Pittsburgh side effects rating scale (PSERS) and the Clinical Global Impressions (CGI) scale.
Results: Parent IOWA showed ADHD behaviour tended to remain the same when the dose of stimulant medication was reduced with placebo but to deteriorate when the dose was reduced without placebo. There were no significant differences between conditions on the Teacher IOWA. PSERS scores were higher at baseline than on 50% dose. On the CGI, there was a significant difference (P = 0.004) between the 50% dose and the 50% + placebo conditions. Individual subject analysis showed that eight subjects met criteria for responder.
Conclusions: Results indicate that the open-label placebo treatment was acceptable and efficacious in the short term for some children.