PROJECT SUMMARY Approximately 6.9 million people in the state of Florida are age 50 and older, and estimates of chronic or severe non-malignant pain in this population range from 35-52%. Of the 33 states (including Florida) with laws that legalize marijuana for medical use, chronic or severe non-malignant pain, conditions with greater prevalence in mid to late life, are recognized as common ailments for which physicians prescribe medical marijuana. In the U.S., chronic pain is the most frequently endorsed reason for medical marijuana use. However, little is known about marijuana use during late-middle age (ages 50–64) and older adulthood (ages 65 and older). While medical marijuana may benefit older adults by reducing pain, the impact of sustained medical marijuana use on functioning during real world tasks such as driving is underexamined. Currently, we do not have enough scientific evidence to differentiate “per se” (quantity of marijuana) versus “impairment” (behaviors exhibited) in driving under the influence cases that involve marijuana use. Physicians, patients and policy makers need data driven guidelines regarding how medical marijuana use affects functioning during real world tasks such as driving among older adults and the potential adverse effects of use. To that end, the National Institute on Drug Abuse (NIDA) and the National Institute on Aging have called for data on medical marijuana and driving performance and medical marijuana use and adverse effects among older adults in particular. A study that examines older adults pre-exposure to medical marijuana and systematically tracks medical marijuana initiation, dosage, and psychomotor functioning will provide evidence of the association between quantity of use and impairment. Thus, the proposed study will test medical marijuana use as the exposure variable in adults age 50 and older and simulated driving performance (i.e. errors in response time, attention, and executive functioning tasks that predict on-road performance) as the primary outcome. Further, we will explore the association between medical marijuana use and adverse effects. To accomplish this, we propose the following aims: Aim 1: Test the association between medical marijuana use and driving errors that predict on-road performance, on a high- fidelity driving simulator, in adults 50 and older with chronic or severe non-malignant pain. Aim 2: Examine the association between medical marijuana use factors (dosage, frequency, CBD vs THC products, and route of administration) and adverse effects in adults age 50 and older. The proposed study is significant because it will prospectively evaluate medical marijuana use and provide an evidence base on the association between use and driving performance and adverse events. The study will obtain detailed marijuana exposure through electronic medical records and blood draws together with repeated measures of driving performance and reports of adverse effects. Further, we will use a c...