Institute of Child Development, University of Minnesota, Minneapolis, MN 55455;
Northwest Metro VA Clinic, Minneapolis Veterans Affairs Health Care System, Ramsey, MN 55303.
Proc Natl Acad Sci U S A. 2021 Apr 6;118(14). doi: 10.1073/pnas.2013180118.
Observational studies have linked cannabis use to an array of negative outcomes, including psychiatric symptoms, cognitive impairment, and educational and occupational underachievement. These associations are particularly strong when cannabis use occurs in adolescence. Nevertheless, causality remains unclear. The purpose of the present study was thus to examine associations between prospectively assessed adolescent cannabis use and young-adult outcomes (psychiatric, cognitive, and socioeconomic) in three longitudinal studies of twins ( = 3,762). Twins reporting greater cumulative cannabis use in adolescence reported higher levels of psychopathology as well as poorer socioeconomic outcomes in young adulthood. However, cannabis use remained associated only with socioeconomic outcomes (i.e., educational attainment, occupational status, and income) in monozygotic-cotwin control analyses, which account fully for shared genetic and environmental confounding. Follow-up analyses examining associations between twin differences in adolescent cannabis use and longitudinal change in academic functioning during the middle- and high-school years provided a possible mechanism for these associations, indicating that greater cannabis use during this period was associated with decreases in grade point average and academic motivation as well as increases in academic problem behavior and school disciplinary problems. Our findings thus suggest that cannabis use in adolescence has potentially causal, deleterious effects on adolescent academic functioning and young-adult socioeconomic outcomes despite little evidence suggesting a strong, causal influence on adult mental health or cognitive ability.
观察性研究将大麻使用与一系列负面结果联系起来，包括精神症状、认知障碍以及教育和职业成就不足。当大麻使用发生在青少年时期时，这些关联尤其强烈。然而，因果关系仍不清楚。因此，本研究的目的是在三项双胞胎纵向研究（n=3762）中，检查青少年大麻使用与青年期结果（精神、认知和社会经济）之间的关联。报告在青少年时期有更多累积大麻使用的双胞胎，在成年早期报告更高水平的精神病理学以及较差的社会经济结果。然而，在同卵双胞胎对照分析中，大麻使用仍然仅与社会经济结果（即教育程度、职业地位和收入）相关，这些分析充分考虑了共同的遗传和环境混杂因素。后续分析检查青少年大麻使用的双胞胎差异与中学和高中期间学业功能的纵向变化之间的关联，为这些关联提供了一种可能的机制，表明在此期间使用更多大麻与平均绩点和学业动机的下降以及学业问题行为和学校纪律问题的增加有关。因此，我们的研究结果表明，尽管几乎没有证据表明大麻对成年人的心理健康或认知能力有强烈的因果影响，但青少年时期的大麻使用对青少年的学业功能和成年后的社会经济结果可能具有潜在的因果不良影响。
