Reward sensitivity and outcome expectancies predict both alcohol and cannabis use in young adults
Creators: name: Depino, Vincenzina
Publisher: name: RMIT University
Year: 2024

description: The primary focus of this thesis was to examine the relationship of reward sensitivity and outcome expectancies, variables traditionally associated with alcohol use, to cannabis use behaviour and to explore the relationship of affect and locus of control to alcohol and cannabis use. It was hypothesised that hazardous alcohol and cannabis use would be related to higher levels of reward sensitivity and to the endorsement of more positive outcome expectancies. It was also hypothesised that positive outcome expectancies would mediate the relationship between reward sensitivity and cannabis use, and that the relationship between reward sensitivity and both alcohol and cannabis use would be moderated by punishment sensitivity. No specific hypotheses were formulated for the relationship of negative outcome expectancies, affect and locus of control of reinforcement to substance use.<br><br>A total of 465 young adults aged between 18 and 35 years completed a questionnaire which assessed substance use patterns, reward and punishment sensitivity, outcome expectancies, locus of control, and affect. Results indicated that higher levels of reward sensitivity reliably distinguished hazardous from non-hazardous alcohol and cannabis users as well as cannabis users from cannabis non-users. The relationship between reward sensitivity and substance use was partially mediated by outcome expectancies, but not moderated by punishment sensitivity. An exploratory factor analysis demonstrated a high rate of concordance between alcohol and cannabis outcome expectancies. Locus of control of reinforcement was found to be unrelated to alcohol and cannabis use behaviour. There was little commonality in the relationship of sensitivity to punishment, negative outcome expectancies, and affect to alcohol and cannabis use. The second focus of this thesis was to pilot an intervention aimed at reducing alcohol use via the challenging of expectations regarding the rewarding outcomes associated with alcohol use in a group of young adult Australian males. A three session intervention was completed by three males aged between 19 and 31 years. The results demonstrated no reduction in hazardous alcohol use or global positive alcohol outcome expectancies at the completion of the intervention program or at a 3-month follow-up. Furthermore, there was no reduction in expectancies of increased sexual interest for any of the participants at the 3-month follow-up compared to baseline, despite a reduction in these expectancies for one of the three participants at the completion of the intervention. A reduction in monthly drinking levels and in expectancies of increased confidence compared to baseline was noted for two of the three participants at the 3-month follow-up. It was concluded overall that there is consistency between the relationships of reward sensitivity and positive outcome expectancies to alcohol and cannabis use and that outcome expectancies may be a proximal mechanism through which reward sensitivity influences alcohol and cannabis use. It was further concluded that whilst causal inferences regarding the effectiveness of the intervention could not be made, the results provide some evidence for the usefulness of this treatment in changing a proportion of the studied outcomes. This potentially provides an incentive for future controlled design research in larger samples and with alternate substances.<br>