A Longitudinal Investigation of Cannabis Use on Adolescent Neurocognitive Development in the ABCD Study®

Objective. Evidence pertaining to the effect of adolescent cannabis use on neurocognitive development has been mixed, with recent reports highlighting the limitations of existing findings. By leveraging the Adolescent Brain Cognitive Development (ABCD) Study® sample, the present study addresses previous methodological constraints to clarify cannabis’s potential effect on cognitive development.Methods. Youth (N=4,191) performed neurocognitive tasks during their baseline (age ~10) and Year 6 (age ~16) follow-up assessments. Domains included overall cognitive function (crystallized/fluid), memory, executive functioning, processing speed, reward sensitivity, and language skills. Lifetime, cumulative cannabis use was divided along a median split to account for skewed data, resulting in no, low (≤5 cannabis use occasions; average=1.8), and high use (>5 use occasions; average=256) groups. Initial models (Bonferroni corrected, n=19) compared Year 6 follow-up cognitive performance between groups while controlling for baseline performance, sex, and age. Sensitivity analyses incorporated 1) socioeconomic status (SES), 2) additional substance use, and 3) SES and additional substance use.Results. Cannabis use during early adolescence was significantly related (adj. p<0.05) to worse crystallized cognitive function (β=[-0.23,-0.21]), memory (β=[-0.35,-0.17]), and language skills (β=[-0.26,-0.13]). Cannabis effects remained generally consistent after controlling for SES alone. After controlling for additional substance use, the unique effect of cannabis use was no longer statistically significant.Conclusions. The present study highlights that cannabis likely has an overall negative effect on neurocognitive development; while present over and above SES, this effect may not be substance specific. Future work aims to disentangle the shared effect of these relationships.