Abstract
INTRODUCTION: This study provides national data on cannabis use type (medical versus recreational only) across individuals aged 19-65 years and associations with overall cannabis use prevalence and frequency, including developmental and historical trends and sociodemographic and policy associations. METHODS: Data collected in 2018-2023 from individuals (N=33,647) aged 19-65 years participating in the Monitoring the Future Panel study were analyzed in 2024-2025. Developmental and historical trends and regression analyses examined past 12-month cannabis use type: no use, recreational-only use, or any medical cannabis used from their own written medical recommendation/prescription (with or without recreational use). RESULTS: Medical use was reported by 2.6% (2.3%, 2.8%) of all respondents and 9.8% (9.0%, 10.6%) of those reporting past 12-month use. Among all respondents, medical-use prevalence did not show evidence of significant developmental trends; among those reporting past 12-month use, there was an age-graded increase in medical use (p<0.001), corresponding to an age-graded decrease in recreational-only use (p<0.001). Medical-use prevalence increased across time in states with medical-use-only policy (p=0.002) but not in other states and was associated with being male (p<0.001). Past 30-day cannabis prevalence and frequency were higher among medical- than recreational-only use groups across ages (p<0.001). CONCLUSIONS: Among U.S. young and middle adults, the proportion reporting medical use was consistent across age; observed age-graded increases in medical use among those reporting past 12-month cannabis use were due to decreasing recreational-only use. Medical use was associated with higher past 30-day frequency across age, indicating that it acts as a consistent risk factor for daily or near-daily use.