Preprint · Jun 18, 2025
Real-Time and Long-Term Effects of Medical Marijuana on Older Adults: Protocol for the Study on Medical Marijuana and its Long-Term Effects (the SMILE study) Prospective Cohort (Preprint)
By Robinson KR, Seeger SD, Nave L et al.
BACKGROUND Older adults represent the fastest-growing group of medical marijuana (MM) users in the United States, with chronic pain being the most common reason for use. Despite this trend, scientific evidence remains limited regarding the short- and long-term effects of MM on critical health outcomes, including cognitive function, physical and mental health, and overall quality of life in this population. To better inform clinical practice and public policy, there is a clear need for more rigorous, longitudinal studies that examine the impact of real-world MM products over time. OBJECTIVE The Study on Medical Marijuana and Its Long-Term Effects on Older Adults (SMILE) is a prospective cohort study with a comparison group of adults with chronic pain not using MM. SMILE includes technology-based remote assessments and quarterly in-person visits. The study aims to 1) determine MM’s short- and long-term effects on pain, physical, emotional, and cognitive functioning, and quality of life in older adults; and 2) identify MM product characteristics and patient subgroups associated with improved outcomes and side effects. METHODS This study will recruit and follow 440 older adults (50 years or older, ~50% >65, ~50% male) with chronic pain for 12 months, as some initiate MM (MM group, n=330) and others do not (comparison group, n=110). Subjective and objective data will be collected at quarterly in-person visits (including survey, cognitive assessments, pain sensory tests, blood pressure collection and blood/urine samples), and via periodic smartphone- and sensor-based measurements at baseline, 3, 6, 9, and 12 months. Smartphone-based ecological momentary assessment (EMA) data will capture detailed MM use patterns and subjective short-term outcomes (e.g., pain intensity rating), which will be supplemented with objective data collected by a Fitbit device (e.g., physical activity and sleep). RESULTS Recruitment for the SMILE study began in July 2022 and is expected to continue until 2025. Participant follow-up will be completed by 2026. CONCLUSIONS With multisource data collected in real-time and over 12 months, our study will provide much-needed scientific evidence addressing: 1) whether MM can reduce pain and improve physical and emotional functioning in the short term among older adults; 2) whether effects of MM last for 12 months and demonstrate changes in quality of life or cognition; and 3) whether health benefits and consequences differ by MM product type and whether individual differences (e.g. sex, baseline pain phenotyping) moderate the relationship. Our findings will offer valuable insights for physicians and patients when considering MM as a treatment option, and will help guide more informed, individualized care decisions.