Early predictors of maturing out of marijuana use among young men

Maturing out of alcohol and cannabis co-use: A test of patterns and personality predictors

OBJECTIVE

Reductions in substance involvement into adulthood are thought to represent a normative maturing out of substance use. However, patterns and predictors of maturing out of alcohol and cannabis co-use remain largely unstudied. Therefore, the current study tested developmental trajectories of alcohol and cannabis use from late adolescence into adulthood and whether late adolescent personality traits predicted trajectory class membership.

METHODS

Data come from a longitudinal study of family history of alcohol disorder (N = 458). Age bands were created to model trajectories of drinking quantity, negative alcohol consequences, and cannabis use frequency from late adolescence (age 18-22) to young adulthood (age 23-28) and adulthood (age 29-36). Participants reported on their sensation seeking, conscientiousness, and neuroticism during late adolescence and their typical drinking quantity, negative alcohol consequences, and cannabis use frequency at each age band.

RESULTS

Three trajectory classes were derived from an initial Parallel Process Growth Mixture Model: (1) low-risk maturing out of alcohol-only use, (2) high-risk maturing out of co-use, and (3) high-risk switchers who increased their cannabis use into adulthood. Late adolescent sensation seeking was associated with higher odds of being in both co-use trajectories, whereas a lack of conscientiousness was associated with higher odds of being a co-use switcher.

CONCLUSIONS

We identified heterogeneity in trajectories of co-use, which suggests that a lack of maturing out of alcohol involvement may be accompanied by increased cannabis use. Moreover, late adolescent personality traits may predispose individuals toward riskier developmental trajectories of substance use into adulthood.

Working Memory Development and Motor Vehicle Crashes in Young Drivers

IMPORTANCE

Adolescent drivers have the highest rate of motor vehicle crashes, and among equally novice drivers, crash risk is inversely age graded. Working memory (WM), crucial to driving hazard awareness, is also age graded, with ongoing development into late adolescence. Variability in WM capacity and growth trajectory positions WM as a candidate crash risk factor for study, clinical screening, and possible preventative intervention.

OBJECTIVE

To test the association between crashes and differential WM development.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study used data from a longitudinal cohort of 118 community youth in Philadelphia, Pennsylvania. Working memory and other risk factors were measured annually from age 11 to 13 years (prelicensure, in 2005) to 14 to 16 years (in 2009), and again at 18 to 20 years (in 2013). In 2015, a follow-up survey of driving experience identified 84 participants who had started driving. Latent growth curve modeling was used to examine the association between variability in the baseline (intercept) and developmental trajectory (slope) of WM and the crash outcome.

MAIN OUTCOMES AND MEASURES

Self-reported crashes were the primary outcome. Variability in the relative growth of WM development along with traits and behaviors associated with risky driving were assessed.

RESULTS

Of 84 participants (39 [46%] male; mean [SD] age, 20.46 [1.09] years), 25 (29.8%) reported they had been involved in at least 1 crash. Controlling for other crash risk factors, the model indicated that variation in the linear slope of WM growth was inversely associated with reporting a crash (b = -6.41; SE = 2.64; P = .02). Crashes were also associated with reckless driving behavior (b = 0.40; SE = 0.18; P = .03). Variation in the intercept of WM was not associated with crashes (b = -0.245; SE = 0.67; P = .72).

CONCLUSIONS AND RELEVANCE

The results suggest that a relatively slower WM growth trajectory is associated with young driver crashes. Routine assessment of WM across adolescence may help to identify at-risk teen drivers and opportunities for providing adaptive interventions (eg, driving aids or training) that can address limitations in WM-related skills that are critical for safe driving.

Neighborhood context and transitions in marijuana use among urban young adults

BACKGROUND

In emerging adulthood when many youth are maturing out of marijuana use, Blacks continue to have high rates of use and disorder. Theory suggests that factors tied to neighborhood disadvantage may partially explain this phenomenon but research is limited.

OBJECTIVES

This study examines the influence of neighborhood physical and social disorder on transitions in marijuana use during emerging adulthood in a low-income urban sample.

METHODS

379 primarily Black young adults residing in low-income neighborhoods in Baltimore City were followed-up annually from ages 18 to 21. Neighborhood environment was evaluated using a valid and reliable field-rater assessment of the residential block. Longitudinal latent class and latent transition analyses were performed.

RESULTS

Fit indices supported three-classes of marijuana use: no use, infrequent use and frequent use. Between ages 18 and 21, young adults tended to transition toward lower levels of use. However, neighborhood physical disorder was associated with transitioning to increased marijuana use (no use to frequent use; AOR = 2.712; p = .023) while positive neighborhood social activity was associated with a decreased risk (AOR = 0.002; p = .013). Neighborhood social activity was also associated with decreases in use (frequent to infrequent use; AOR = 2.342; p = .020). Conclusions/Importance: These findings demonstrate that physical disorder within the context of a low-income urban neighborhood adversely impacts marijuana use. However, even in the presence of physical disorder, interventions that foster collective efficacy among residents through positive social activity may prevent initiation and progression of marijuana use.

Becoming a medical marijuana user

BACKGROUND

Since marijuana became legal for medical use in California in 1996, reasons for medical use among medical marijuana patients (MMP) have become increasingly well described in qualitative studies. However, few studies have detailed how the use of marijuana for medical purposes fits into the broader career trajectories of either becoming a marijuana user or becoming a MMP, including the social influences on medical use.

METHODS

Young adult MMP (N=40) aged 18 to 26 years old were recruited in Los Angeles, CA in 2014-15 and administered a semi-structured interview that included questions focusing on marijuana use practices before and after becoming MMP.

RESULTS

MMP were categorized into three trajectory groups: primarily medical users (n=30); primarily non-medical users (n=3); and medical users who transitioned to non-medical users (n=7). Most medical users discovered medicinal effects from marijuana in the context of non-medical use as adolescents prior to becoming MMP. Becoming a mature MMP followed interactions with dispensary staff or further self-exploration of medical uses and often involved a social process that helped confirm the legitimacy of medical use and identity as a medical user. In some cases, MMP transitioned back to non-medical users as health conditions improved or remained primarily non-medical users even after becoming MMP for reasons unrelated to health, e.g., protection against arrest.

CONCLUSION

Becoming a medical marijuana user was an important career trajectory that was influenced by early discoveries of effective medicinal use, interaction with proponents of medical use at dispensaries, experiences with new kinds of medical use, and the demands of particular health condition requiring more or less treatment with marijuana.