Electronic Theses and Dissertations





Date of Award


Document Type


Degree Name

Doctor of Philosophy




Clinical Psychology

Committee Chair

James G Murphy

Committee Member

Leslie A Robinson

Committee Member

Meghan E McDevitt-Murphy

Committee Member

Charles D Blaha


Brief motivational interventions (BMIs) have been shown to be efficacious in reducing heavy drinking and drug use among college students; however, effect sizes are small and more research is needed to identify predictors of responsiveness to these interventions. Depression, distress tolerance, delay discounting, and the reinforcing efficacy of substances have been implicated in substance use and may predict problem severity. Further, preliminary evidence suggests that these factors may be important predictors of treatment outcomes, but few studies have examined these constructs in this manner. This study tested a novel intervention approach that involves a BMI plus a supplemental intervention targeting behavioral economic and mood-related variables (Substance-Free Activity Session; SFAS). Participants were 97 college students who reported one or more past-month heavy drinking episodes. After completing an alcohol and drug- focused MI, participants were randomized to either the SFAS or an Education control session. The combination of the MI plus SFAS was associated with significantly greater reductions in drinking and drug use compared to the MI plus EDU at the 6-month follow-up. Across the two conditions, levels of depression were lower at 1 and 6 months post intervention and one measure of reinforcing efficacy was lower at 1-month follow-up suggesting a BMI may be effective at reducing depression and alcohol demand. Lower baseline proportion of reinforcement derived from substances and higher distress tolerance were predictive of better outcomes across conditions. Moderation analyses indicated that students with lower distress tolerance and higher discounting responded better to the MI + EDU session and students with lower discounting and reinforcing efficacy responded better to MI + SFAS. Changes in mood and behavioral economic variables did not mediate changes in substance use. These results suggest that a BMI + supplemental mood and behavioral economic session may be more effective overall in helping students reduce their drinking and drug use, but not necessarily through the targeted behavioral economic and mood-related mechanisms. So, although these variables may predict response to intervention, and students who vary in these domains may respond differentially to various interventions, more research is necessary to determine mechanisms of change in this novel intervention.


Data is provided by the student.

Library Comment

dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.