Cannabis use, microbial diversity, and Dialister abundance in older adults with HIV: a cross-sectional study

Abstract Objectives People living with HIV (PLWH) frequently experience gastrointestinal symptoms linked to dysbiosis, impaired mucosal barrier integrity, and persistent immune activation. Cannabis is widely used for symptom management by PLWH, but its effects on the gut microbiome are unclear. Methods We conducted a cross-sectional analysis of 63 PLWH (mean age 59.4 years; 71.4% Black or Hispanic) enrolled in the Marijuana Associated Planning and Long-term Effects study and its microbiome substudy. Participants provided fecal samples for 16S rRNA sequencing. Cannabis use was quantified using a validated Timeline Followback. Alpha diversity was estimated using the Shannon index, beta diversity with Bray-Curtis dissimilarity and PERMANOVA, and genus-level abundance using the IFAA method. Models adjusted for sex, age, and education. Results Higher cannabis consumption was significantly associated with reduced alpha diversity (β = −1.23, p =0.038). No significant differences in beta diversity were observed between high and low-to-no groups ( p =0.35). At the genus level, Dialister abundance showed a significant dose-dependent association with cannabis use, with a 14.4% reduction in abundance per 50 mg increase in THC per use-day (q=0.034). Reduced alpha diversity and Dialister depletion are notable given links to impaired mucosal barrier integrity, microbial translocation, and systemic immune activation in HIV. Conclusion Cannabis consumption in PLWH was associated with lower microbial diversity and reduced Dialister abundance, a taxon with dual roles in mucosal integrity and gastrointestinal symptom modulation. These findings suggest cannabis may modify HIV-associated dysbiosis, warranting further longitudinal studies to disentangle symptomatic benefits from long-term impacts on mucosal health and systemic inflammation.