RESIDENT: The Potential Impact of Cannabis Use and Increased Dementia Risk: A Scoping Review

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Presenting Author(s): Harman Sidhu

Co-Author(s): Dr. Dallas Seitz, Thoman Hogan, Lynn Tan, Ti-Amo Richards

Date and time: 20 Mar 2026 from 15:00 to 15:15

Location: Saddleback & Glacier  

Learning Objectives

1. Describe the current evidence linking cannabis use to dementia-related outcomes; 

2. Explain proposed neurobiological mechanisms connecting cannabis exposure to dementia-risk; and

3. Identify gaps, limitations, and future research priorities in the cannabis-dementia literature.

Abstract

Objective: This scoping review aimed to examine existing evidence on the relationship between cannabis use and dementia risk. 

Methods: Following PRISMA guidelines, a systematic search of Ovid Medline, PubMed, PsycINFO, and Scopus (EMBASE) was conducted for English-language studies published before November 1, 2024. Experimental and observational human studies examining cannabis exposure (including THC or CBD) and dementia-related outcomes were included. Screening and data extraction were completed by two independent reviewers, with a narrative synthesis of findings. 

Results: Of approximately 3,215 records, 9 studies met inclusion criteria, representing imaging, cohort, observational, experimental, and case report designs. Imaging studies reported associations between cannabis use and reduced hippocampal perfusion or volume, patterns consistent with early Alzheimer's disease. A large veteran cohort suggested cannabis use was an independent risk factor for cognitive disorders in individuals with traumatic brain injury. Population-based studies in older adults showed mixed cognitive findings, with some reporting higher subjective memory complaints and others finding no objective impairment. Experimental studies noted mild executive dysfunction among chronic users. One case report described early-onset frontotemporal dementia in the context of heavy cannabis use. Across studies, variability in exposure and methods limited comparability, and most designs were cross-sectional. 

Conclusions: Current evidence suggests possible associations between chronic or early cannabis exposure and cognitive or hippocampal changes relevant to dementia risk. However, findings are inconsistent, causality cannot be inferred, and more longitudinal research is needed.

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