Self-reported cognition and marijuana use in older adults: Results from the national epidemiologic survey on alcohol and related conditions-III.

Marijuana use among older adults is on an unprecedented rise, yet little is known about its effects on cognition in this population where, due to advanced age, risk for cognitive decline is high. Thus, we investigated whether marijuana use and use characteristics were associated with self-reported cognition among older adults ages ≥ 50 years using the National Epidemiologic Survey on Alcohol and Related Conditions-III. Respondents either had never used marijuana ("never": n = 10,976), used but not in the past 12 months ("former": n = 2990), or used in the past 12 months ("current": n = 712). Self-reported cognition was measured using the Executive Function Index. Marijuana and substance use characteristics were obtained using the Alcohol Use Disorder and Associated Disabilities Interview Schedule-5. Covariates included demographics, mental health and disability, and comorbid mental and substance use disorder. Using general linear models of cross-sectional data, we found that current users, particularly those with cannabis use disorder, reported worse cognition than never or former users, but these effects were small in magnitude. Among both former and current users, greater duration of past use was associated with worse cognition. Frequent use within the past 12 months was associated with worse cognition among current users, but daily users reported better cognition compared to monthly or weekly users. Thus, marijuana use may impact self-reported cognition in older adulthood, although these effects may be subtle, specific to particular use characteristics, and possibly affected by self-awareness of deficits. Future work using objective measures such as neuropsychological testing or neuroimaging may better elucidate these effects.