Complementarity in daily marijuana and alcohol among emerging adults.

Abstract

Objective: The relationship between marijuana and alcohol use among late adolescents was examined as whether marijuana use was related to quantity of alcohol consumed that day, and whether changes in marijuana and alcohol use frequency over 3 years were related. Method: College students (n = 375) reported marijuana and alcohol use for 28 days over 3 years. Results: Within-day analyses showed that more alcohol was consumed on days on which marijuana was used. Co-use varied by alcohol use problems, day of week, and year in study; the relation between marijuana and alcohol use was stronger among those who reported less problematic alcohol use, on weekdays, and as time increased. Daily level co-use relations also differed marginally by gender. At the annual level, there was a marginal relation between changes in use such that increasing use of one substance over time was weakly associated with increased use of the other substance over the same time period. Conclusions: Results add to the emerging conclusion of complementary marijuana and alcohol co-use within a single day, showing it occurs for both women and men, across a full range of marijuana use, and increases with time while being affected by alcohol use problems and day of week. The overall strong co-use relationship highlights risky behavior among late adolescents and supports an emphasis on common underlying substance use causes. However, the different pattern when assessed yearly demonstrates the importance of tailoring the timescale of analysis to the specific substance use question. Public Health Significance StatementResults show that late adolescents making the transition to college co-use marijuana and alcohol within individual days, with marijuana use on a particular day associated with more drinks consumed the same day. The relationship between daily marijuana and alcohol use was weaker among those with more problematic alcohol use, on weekends, and marginally so among men. Marijuana use also showed a stronger relation to alcohol use across the measurement period, suggesting co-use risk increased across the college transition. The consistent evidence of within-day co-use suggests substance use interventions need to explicitly consider motivations for and target co-use.

Simultaneous Alcohol and Marijuana Use Among Young Adults: A Scoping Review of Prevalence, Patterns, Psychosocial Correlates, and Consequences

“… 45 For same-day co-use, several papers found that more alcohol was consumed on days marijuana was also used relative to days that only alcohol was used. 46 – 48 Between-person findings in these papers provided some evidence that greater average alcohol intake was associated with more frequent SAM use 32 and less frequent same-day co-use. 46 , 47 …”

Unplanned versus planned simultaneous alcohol and cannabis use in the daily lives of a predominantly white college student sample: What are the motives, contexts, and outcomes?

“…Simultaneous alcohol and cannabis use (also sometimes called simultaneous alcohol and marijuana use) is common in the U.S. (Subbaraman & Kerr, 2015, 2020), particularly among college students (White et al, 2019). Simultaneous use has been linked to increased alcohol and cannabis consumption and negative consequences compared to single-substance use (Ito et al, 2021; Lee et al, 2020; Linden-Carmichael et al, 2020; Metrik et al, 2018). However, almost no research has explored whether college students plan for simultaneous use or if it is unplanned and incidental, for example, unintentionally using cannabis after having been drinking, which has implications for its relations to etiological correlates (e.g., motives, contexts) and outcomes (Pearson & Henson, 2013).…”

Combined use of alcohol and cannabis: Introduction to the special issue.

“…In contrast, Waddell et al (2021) found greater support for substitution, such that for individuals with mean or low levels of impulsive traits (i.e., positive urgency and lack of perseverance), quantity of alcohol use was lower on days with co-use. Critically, there were several noteworthy differences between the samples—whereas Ito et al (2021) examined associations among a sample of college students, Waddell et al (2021) studied a slightly older sample of veterans, a group at increased risk for impulsivity and substance use (Bhalla et al, 2019; Gunn et al, 2020; Hawn et al, 2019; Meadows et al, 2018). These findings highlight the importance of examining person-level factors when considering one’s risk for increasing alcohol or cannabis use on co-use occasions.…”

“…Daily diary and EMA designs are well suited to examine complementarity or substitution effects for alcohol and cannabis use (see Gunn et al, 2019; O’Hara et al, 2016). In this special issue, disparate findings emerged on this research question: Ito et al (2021) found evidence for complementarity in a sample of college students such that more alcohol was consumed on days when cannabis was used. In contrast, Waddell et al (2021) found greater support for substitution, such that for individuals with mean or low levels of impulsive traits (i.e., positive urgency and lack of perseverance), quantity of alcohol use was lower on days with co-use.…”