Young people who engage in binge drinking and cannabis use did not appear to be influenced by specific advice from their family doctors to reduce excessive use of these substances, indicate the results from a clinical trial published in CMAJ (Canadian Medical Association Journal).

Binge drinking (more than 5 drinks in 1 sitting) and excessive use of cannabis in youth have been associated with later health issues in adults. In the US and Europe, about 30% to 50% of adolescents and young adults are binge drinkers, and about 10% use cannabis excessively. Research indicates that counselling of adults about binge drinking can positively change behaviour, although the research for this approach with young people is less clear.

To determine whether screening for excessive substance use and counselling by family doctors could reduce risky behaviour, researchers from Switzerland, the United Kingdom and Australia launched the Primary Care Intervention Addressing Substance Misuse in Adolescents (PRISM-Ado) randomized controlled trial. The trial involved 33 family doctors and pediatricians in the French-speaking part of Switzerland and 594 youth aged 15 to 24 years who were asked about their health, use of alcohol and drugs, and sociodemographic factors. The physicians in the intervention group received training in a proven motivational interview style that has shown success when used with young people. Most of the physicians had previous moderate to extensive training in working with youth and alcohol-related issues. Doctors were randomized to an intervention or control group.

About half the participants (49%) indicated that they engaged in binge drinking and/or used cannabis. There was no significant difference between the group that received counselling and the one that did not in rates of excessive substance use rates at 3, 6 and 12 months after counselling. By 12 months, there was a 28% reduction in the number of excessive substance users among those who had reported excessive use at the start of the study.

"Training family doctors to deliver a brief intervention to address excessive substance use failed to reduce binge drinking and excessive cannabis use among young patients at 3, 6 and 12 months follow-up," writes Dr. Dagmar Haller, University of Geneva and Geneva University Hospitals, Switzerland, and the University of Melbourne, Australia, with coauthors.

"Formal training in using the brief intervention may only have had a modest impact on the ability of experienced and interested family physicians to adapt their communication style with young people," suggest the authors. "Improved outcomes in both groups may also have been due to the patients completing the baseline survey. This step in the study protocol may have encouraged the patients who were already primed through public health and education messages to identify a personal need for change."

The authors suggest that a screening approach targeted specifically to youth with additional follow-up calls or visits might be more successful.

"These negative results of our trial do not undermine a possible role for family physicians in modifying substance use behaviours in adolescence," write the authors. "Further research on interventions with a stronger emphasis on multisectoral collaborations, effective screening and longer follow-up may provide more."