Placebo control groups in trials of major depressive disorder among older patients

Ethical concerns have been raised regarding the continued use of placebo control groups in randomized controlled trials of antidepressant medications for major depressive disorder. These concerns may be especially relevant for geriatric patients who may experience significant morbidity related to major depressive disorder.

Sixty-eight randomized placebo-controlled trials of antidepressant medication for major depressive disorder were examined, 6 of which measured response to medication and placebo in elderly patients.

Although this review is limited by the small number of studies focusing on older individuals, there are a number of similarities and some differences in geriatric studies in comparison to other studies of adults with major depressive disorder. In comparison to studies of younger adults, the proportion of patients responding to placebo in studies of older individuals was slightly higher, and the proportion of patients responding to active medication was lower, leading to a significantly reduced effect size.

The scientific importance of using control groups in studies of major depression poses ethical challenges. However, the substantial and variable response to placebo and the inability to predict accurately the response to placebo or medication raise serious doubts about the scientific value of trials of new medications in which there is no placebo group.