Descriptive norms but not harm reduction strategies as a mediator of personalized boosters after a computerized college drinking intervention.
BACKGROUND
Computer-delivered programs to reduce college drinking have strong appeal but are sometimes less efficacious than their in-person counterparts. Boosters may be an ideal way to strengthen and extend the effects of computerized interventions while maintaining low cost and easy dissemination. However, little is known about how they work. Consequently, the current study aimed to explore descriptive perceived drinking norms and use of protective behavioral strategies (PBS) as potential mediators of booster effects. We also examined norms and PBS as mediators of the main intervention. The present study was a follow-up analysis of data from a randomized controlled trial (Braitman & Lau-Barraco, 2018) testing the efficacy of emailed boosters containing personalized feedback after a computerized alcohol intervention.


METHODS
Participants were 537 (67.4% women) emerging adult college drinkers (M age = 19.65, SD = 1.67). They were randomly assigned to one of three conditions: general health education, alcohol intervention only, or alcohol intervention plus booster email. Participants completed assessments at baseline and follow-ups through 9 months.


RESULTS
Descriptive norms was a mediator of booster efficacy where receiving the booster yielded stronger reductions in alcohol use through reduced concurrent norms; however, fully longitudinal models did not reach significance. There was also an indirect effect for the intervention where those who received the intervention experienced an increase in drinking through increased concurrent norms. However, a stronger direct effect was found where those who received the intervention experienced a stronger decrease in drinking after controlling for norms. There was not support for PBS as a mediator of booster or intervention efficacy.


CONCLUSION
The present study was the first, to our knowledge, to demonstrate a potential mechanism of change in booster interventions. A simple, succinct reminder via email lead to reductions in perceptions of how much peers drink and this led to reductions in alcohol consumption. Our findings support the promise of utilizing brief and easily implemented targeted messaging to enhance the potency of computerized interventions for college drinkers.