Researchers studied the impact of low-level marijuana (MJ) use on cognitive maturation and schizophrenia risk in adolescents. Two samples, primarily reporting minimal MJ use, were analyzed for cognitive performance before and after MJ initiation. The Iowa sample included relatives of patients with schizophrenia and control subjects, undergoing tests over 36 months, with 26.5% reporting emergent MJ use (eMJ). A birth cohort sample (n = 3463) underwent substance use and attention assessments between ages 10 and 15 years. Mixed linear models and regression analyses evaluated eMJ effects on cognitive performance over time.

Results showed that in the Iowa sample, eMJ was linked to less improvement in five of eight cognitive domains, including attention and working memory. First-degree relatives with eMJ also showed less improvement in processing speed and reasoning. In the birth cohort, greater variability in reaction times, indicating poorer attention, was associated with more frequent MJ use. These findings suggest that even low-level MJ use disrupts cognitive maturation in adolescents and exacerbates cognitive deficits linked to familial schizophrenia risk. This emphasizes the need to limit adolescent access to MJ, especially high-potency variants.

Reference: Ho BC, Barry AB, Koeppel JA, et al. Recreational Marijuana Use, Adolescent Cognitive Development, and Schizophrenia Susceptibility. Biol Psychiatry Glob Open Sci. 2022 Feb 8;3(2):222-232. doi: 10.1016/j.bpsgos.2022.01.008. PMID: 37124347; PMCID: PMC10140454.