A systematic review of research on adolescent solitary alcohol and marijuana use in the United States.

BACKGROUND AND AIMS: Alcohol use and marijuana use tend to be social activities among adolescents. Some youth use alcohol or marijuana while alone. This article provides a framework for examining the risk factors for and consequences of solitary alcohol and marijuana use, grounded in a motivational model that emphasizes coping with negative emotions, and provides the first systematic review of research on solitary alcohol and marijuana use among middle school- and high school-aged adolescents in the United States. METHODS: PubMed, PsycINFO and Web of Science were searched. Articles were included if they mention solitary alcohol or marijuana (or illicit drug) use among adolescents aged 12-18 years. Studies on non-human animals, college students, non-English language publications and articles exclusively about solitary tobacco or inhalant use were excluded. Overall, 22 articles were selected. RESULTS: Prevalence of adolescent solitary alcohol and marijuana use was relatively high (e.g. 14% life-time solitary drinking in the general adolescent population), particularly in high-risk subgroups (e.g. 38.8% life-time solitary drinking in a sample of youth recruited from clinical and community settings). Risk factors for solitary alcohol and marijuana use include earlier onset and heavier use, coping motives, negative emotions and positive expectancies about use. Solitary alcohol and marijuana use are prospectively associated with later substance use disorder (SUD) symptoms, diminished academic performance and perceived health. CONCLUSIONS: Approximately 1 in 7 adolescents in the US appear to have engaged in solitary alcohol and marijuana use at some point. It is positively associated with extent of drinking and marijuana use, cop;ing motives, negative emotions, and positive expectancies, as well as subsequent SUD symptoms and poor academic and health-related outcomes.

Solitary cannabis use in adolescence as a correlate and predictor of cannabis problems.

BACKGROUND: Most adolescent cannabis use occurs in social settings among peers. Solitary cannabis use during adolescence may represent an informative divergence from normative behavior with important implications for understanding risk for cannabis problems. This longitudinal study examined associations of adolescent solitary cannabis use with levels of cannabis use and problems in adolescence and in young adulthood. METHODS: Cannabis using-adolescents aged 12-18 were recruited from clinical programs (n=354; 43.8% female; 83.3% Caucasian) and community sources (n=93; 52.7% female; 80.6% Caucasian). Participants reported on cannabis use patterns and diagnostic symptoms at baseline and multiple follow-ups into young adulthood. RESULTS: Compared to social-only users, adolescent solitary cannabis users were more likely to be male and reported more frequent cannabis use and more DSM-IV cannabis use disorder (CUD) symptoms. Regression analyses showed that solitary cannabis use in adolescence predicted CUD symptom counts in young adulthood (age 25) after controlling for demographic variables and the frequency of adolescent cannabis use. However, solitary adolescent cannabis use was no longer predictive of age 25 CUD symptoms after additionally controlling for adolescent CUD symptoms. CONCLUSIONS: Solitary cannabis use is associated with greater cannabis use and problems during adolescence, but evidence is mixed that it predicts young adult cannabis problems.