Marijuana, the mostly widely used illicit drug in the United States, is disproportionately prevalent in persons with HIV. Despite the promise of cannabinoids as a therapeutic agent for HIV disease, chronic marijuana use is also associated with potential neurobiological harms. Neurological complications of HIV disease remain a persistent clinical problem even in the age of combination antiretroviral therapy. Our prior work demonstrates that chronic marijuana use exacerbates HIV-associated cognitive deficits, even in patients with sustained HIV suppression, and is associated with complex brain abnormalities in persons with HIV. Additional preliminary data shows reduced levels of inflammatory cytokines in marijuana users compared to non users that correlate with cognitive function. Building on a strong foundation of neuroHIV and addiction research by our multidisciplinary team, this hypothesis-driven proposal will use an in vivo model to investigate the underlying pathophysiological mechanisms of HIV-associated brain dysfunction. Using this translational approach, we aim to: (1) investigate the independent and additive effects of HIV disease and chronic marijuana use on inflammatory processes linked to brain injury; (2) model the longitudinal relationship of chronic marijuana use to HIV-induced inflammation and its relationship to brain injury; and (3) determine the relationship of cannabinoid metabolites to inflammatory and neuronal markers. A prospective cohort of 140 adults stratified marijuana status will complete cutting-edge neuroimaging, immune and cytokine profiling, and neuropsychological testing three times over 2 years. Capitalizing on ultrahigh-resolution magnetic resonance imaging (MRI) capabilities at Duke, we will use multimodal, multi-parametric sequences to investigate neuroinflammatory and neurodegenerative processes. The baseline will include comparison groups of 80 HIV- negative adults. The central hypothesis is that marijuana use disrupts the central nervous system through both anti-inflammatory and neurotoxic pathways. Our proposal responds directly to RFA-DA-20-022, which calls for mechanistic studies to “discern the impact of chronic and/or heavy use of cannabis on the interaction between endocannabinoid system function and HIV-induced inflammation” and “its consequent effects on nervous system function.” This research uses a team science approach to address topics aligned with NIH HIV/AIDS research priorities, including a focus on persistent inflammation and HIV-relevant comorbid conditions [NOT- 20-018]. By considering both beneficial and adverse effects of marijuana available in the United States market, our proposal has strong translational potential to guide clinical recommendations for medical and recreational marijuana in persons with HIV. This timely and ecologically valid research is also expected to advance our understanding of the inflammatory mechanisms through which cannabinoids modulate neurological disorders and other comorbidities in persons with HIV.

Public Health Relevance Neurological complications of HIV disease remain a persistent clinical problem even in the age of combination antiretroviral therapy. Marijuana, which is the most commonly abused drug among persons with HIV, may have therapeutic benefit, but it may also be associated with neurobiological harms. This study applies a hypothesis-driven approach to examine the effects of chronic marijuana use on HIV-associated inflammation and its subsequent impacts on central nervous system function, with the goal of identifying the mechanisms through which cannabinoids modulate neurological disorders and other comorbidities in persons with HIV.