Associations of Low‐Level Prenatal Alcohol and Cannabis Exposure With Adolescent Cognitive Trajectories

BACKGROUND: No studies have examined the differential and combined effects of prenatal alcohol and cannabis exposure (PAE/PCE) on longitudinal trajectories of adolescent cognitive development. Further, previous alcohol research is mixed, with some evidence for negative PAE effects on cognition and other studies reporting null or positive associations. This study examined associations between PAE, PCE, and growth trajectories of adolescent cognition in a large, diverse sample. METHODS: = 14.07). Retrospective parent report of PAE and PCE was assessed at baseline. Univariate growth trajectories were estimated for cognitive measures: Pattern Comparison, Picture Sequence Memory, Oral Reading, Flanker Task, and Picture Vocabulary. Cross-product terms for PAE and PCE tested combined use. RESULTS: Most mothers reported no prenatal alcohol (n = 8257; 74%) or cannabis (n = 10,812; 94%) use. Overall, use was low: across pregnancy, women reporting any alcohol use averaged 33.31 drinks, and those reporting any cannabis use averaged 33.00 use occasions. Before including covariates, there were negative main effects of PCE and positive main effects of PAE on intercepts for all five cognitive domains. There was little evidence for PCE/PAE effects on slopes for cognition. After adding covariates, no negative effects of PCE remained. Small positive PAE effects on intercepts for multiple domains persisted. Cross-product terms for combined exposure were not significant. CONCLUSIONS: Little evidence emerged for negative effects of low PAE, PCE, or combined exposure on adolescents' cognitive development after accounting for sociodemographic factors. Light drinking in families with social features positively associated with cognitive ability may result in few negative consequences. This study is the first to demonstrate weak evidence for adverse differential and combined low-level PAE and PCE effects on the development of adolescent cognition.