Do patients with alcohol dependence respond to placebo? Results from the COMBINE Study

The purpose of this study was to examine the nature of the effect of placebo medication plus accompanying medical management in the treatment of alcohol dependence.

The National Institute on Alcohol Abuse and Alcoholism COMBINE (Combining Medications and Behavioral Interventions) study, a randomized controlled double-blind trial of 1,383 alcohol-dependent patients, compared combinations of medications (acamprosate [Campral] and naltrexone [ReVia]) and behavioral therapy (medical management and specialist-delivered behavioral therapy) for alcohol dependence. This report focuses on a subset of that study population (n = 466) receiving (1) specialized behavioral therapy alone (without pills), (2) specialized behavioral therapy + placebo medication + medical management, or (3) placebo + medical management.

During 16 weeks of treatment, participants receiving behavioral therapy alone had a lower percentage of days abstinent (66.6%) than did the participants receiving placebo and medical management (73.1%) or those receiving specialized behavioral therapy + placebo + medical management (79.4%). The group receiving behavioral therapy alone relapsed to heavy drinking more often (79.0%) than those receiving behavioral therapy + placebo + medical management (71.2%). This report focuses on potential explanations for this finding. The two groups of participants receiving placebo + medical management were more likely to attend Alcoholics Anonymous meetings during treatment (32.7% and 32.0% vs 20.4%) and were less likely to withdraw from treatment (14.1% and 22.9% vs 29.3%).

There appeared to be a significant "placebo effect" in the COMBINE Study, consisting of pill taking and seeing a health care professional. Contributing factors to the placebo response may have included pill taking itself, the benefits of meeting with a medical professional, repeated advice to attend Alcoholics Anonymous, and optimism about a medication effect.