Date of Award
2026
Degree Type
Dissertation
Degree Name
Doctor of Philosophy in Psychology
Specialization
Behavioral Science
Department
Psychology
First Advisor
Amy Stamates
Abstract
Simultaneous use of alcohol and cannabis, or co-use (i.e., the use of both substances so that effects overlap), is an increasingly significant public health concern among young adults between the ages of 18 and 25 in the U.S. (SAMHSA 2025; Terry-McElrath & Patrick, 2018). Protective behavioral strategies (PBS; i.e., tactics used to modify or limit substance use related harm; Pearson, 2013) have been robustly linked to fewer negative outcomes (e.g., lower use quantity, frequency, and consequences) for alcohol- and cannabis-only occasions (Bravo et al., 2016; Bravo et al., 2017; Bravo et al., 2019; Pearson, 2013; Pedersen et al., 2016; Pedersen et al., 2017; Prince et al., 2019; Treloar et al., 2015). However, research has not examined PBS in the context of co-use occasions. Consequently, the purpose of this study was to examine the extent that alcohol and cannabis PBS are used and associated with alcohol and cannabis use outcomes on co-use occasions relative to alcohol- and cannabis-only occasions. There were three aims: 1) To assess whether alcohol and cannabis PBS are used more frequently on alcohol- or cannabis-only occasions relative to co-use occasions, 2) to determine whether alcohol and cannabis PBS are associated with levels of alcohol use, cannabis use, and consequences experienced on alcohol- and cannabis-only occasions relative to co-use occasions, and 3) to identify daily factors (environmental context, social setting) related to alcohol and cannabis PBS on alcohol- and cannabis-only occasions relative to co-use occasions. Participants were 123 undergraduate students (63% female; n = 77) who reported engaging in co-use at least weekly. Participants completed four weekends of phone surveys Thursday-Sunday (16 days total), which assessed alcohol use, cannabis use, co-use, and the use of protective behavioral strategies. Multilevel modeling analyses showed that at the within-person level, 1) there was no effect of PBS use on likelihood of a co-use day relative to a single-substance use day, 2) there was no interaction between type of substance use day (i.e., co-use vs. single-substance) and PBS on level of substance use or negative consequences, and 3) there was an interaction between using alcohol or cannabis around people from multiple relationship categories (i.e., around friends and strangers) and type of substance use day and between using around friends only and type of substance use day on PBS. Specifically, the relationship between using around multiple types of people and PBS use was stronger on cannabis-only days relative to co-use days. Contrastingly, using around friends only was related to lower PBS use on cannabis-only days relative to co-use days. There was no interaction between substance use location and substance use day on PBS. Overall, the sample engaged in heavy substance use and used a similar level of alcohol and cannabis on co-use days as compared to single-substance use days. Participants also reported using a similar amount of PBS on co-use days as compared to single-substance use days. Taken together, level of use and contextual factors may be important for interventions targeting harm reduction on co-use days.
Recommended Citation
Todaro, Sabrina, "PROTECTIVE BEHAVIORAL STRATEGIES ON ALCOHOL AND CANNABIS CO-USE OCCASIONS" (2026). Open Access Dissertations. Paper 4560.
https://digitalcommons.uri.edu/oa_diss/4560