The effects of alcohol and tobacco co-use on momentary subjective cannabis effects: Risk for increasingly hazardous cannabis use

Restricted (Penn State Only)
- Author:
- Bedillion, Margaret
- Graduate Program:
- Biobehavioral Health
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- May 22, 2024
- Committee Members:
- Thomas Gould, Program Head/Chair
Eric Claus, Major Field Member
Emily Ansell, Chair & Dissertation Advisor
Rina Eiden, Outside Unit & Field Member
Robert Turrisi, Major Field Member
Joshua Smyth, Major Field Member - Keywords:
- EMA
co-use
cannabis
alcohol
tobacco
subjective drug effects - Abstract:
- The rates of cannabis co-use with alcohol and tobacco among young adults have continued to rise in recent years. Co-use places individuals at greater risk for driving under the influence, poorer mental-health and cognition, and co-morbid substance use disorder, compared to single-substance use. Theoretical models of substance use suggest that individuals engage in co-use to either complement, that is, experience an enhanced or additive effect of using the substances together or counter the effects of the other substance. Notably, studies show that subjective responses to alcohol, cannabis, and tobacco are central to the development of substance use disorders. Despite the increased prevalence and risk associated with co-use, very little research has examined how co-use patterns may influence moment-to-moment changes in subjective responses. The narrative review in this dissertation outlines the inconsistent and null findings on co-use and subjective drug effects in both experimental and naturalistic settings. The two empirical studies in this dissertation utilized 21 days of ecological momentary assessment to examine whether cannabis co-use with alcohol or tobacco differentially affects subjective responses in daily life. These studies also examined whether subjective responses to co-use were associated with hazardous cannabis use over time. Findings related to the co-use of alcohol and cannabis showed that when these substances were used within close proximity to each other, subjective responses (e.g., intoxication, stimulation, bad effects) were significantly higher compared to cannabis-only use moments. Additionally, the association between co-use days and changes in subjective intoxication varied depending on the quantification of the outcome (e.g., day-average, day-peak, end). Across two metrics of alcohol consumption (standard drinks, eBAC), results showed that consuming a greater amount of alcohol with cannabis did not lead to greater subjective intoxication during co-use episodes. Furthermore, the extent to which an individual becomes more intoxicated when co-using alcohol and cannabis, the greater the risk for hazardous cannabis use six months and one year later. Risk for increasingly hazardous cannabis use was greater for women when alcohol and cannabis co-use occurred farther apart. Conversely, risk for increasingly hazardous cannabis use was greater for men when co-use occurred within close proximity. Findings related to the co-use of cannabis and tobacco showed that sequential use was associated with higher stimulation and more good effects, liking, and willingness to take cannabis again. Whereas co-administration of tobacco and cannabis resulted in lower subjective intoxication and liking. This suggests that different patterns of tobacco and cannabis co-use may have distinct impacts on subjective responses. Moreover, the extent to which an individual becomes more stimulated during sequential use, the greater the risk for hazardous cannabis use six months later. Stimulatory effects related to sequential use may serve as an acute marker of risk. Overall, findings from this dissertation point to several key considerations when evaluating the effects of co-use in naturalistic settings: the temporal proximity of cannabis use with other substances, the amount of each substance consumed, and the methodological approach being implemented. Findings may be used to inform harm-reduction and prevention approaches to target potential risks related to co-use among young adults.