The Multimodal Treatment Study of Children With Attention-Deficit/Hyperactivity Disorder (MTA)1 was seriously flawed.
First, the study was not placebo controlled or double blind. The MTA not only lacked a placebo control group, but in drawing their conclusions, the investigators relied on evaluations made by teachers and parents who were not blinded to the treatment. The MTA was "open label," with all the scientific flaws associated with such studies. As Nies and Spielberg2 observed, "Placebo effects, which occur in a large percentage of patients, can confound many studies—particularly those that involve subject responses; controls must take this into account."2(p45)
Breggin PR. MTA Study Has Flaws. Arch Gen Psychiatry. 2001;58(12):1184. doi:10.1001/archpsyc.58.12.1184