Still Dazed and Confused: Demographic Drift and the Persistence of Sampling Bias in Cannabis Research.

Rudroff T. · Life (Basel, Switzerland) · 2026

**Background & Methods** This is a narrative review examining sampling bias and demographic representation across cannabis research literature published through 2026. The author traces mismatches between actual cannabis users (increasingly older adults aged 65+) and study populations across five research domains: clinical trials, neuroimaging, inflammation physiology, endocannabinoid function, and psychiatric outcomes. **Key Findings** • **Population Diversity Deficit**: Cannabis research systematically over-represents young, healthy, university-recruited participants while understudying the fastest-growing user demographic—adults aged 65 and older—creating a significant gap between evidence and the populations self-medicating with cannabis for neurological disease and chronic pain. • **Heterogeneity Suppression Problem**: Research treats demographically diverse cannabis users as a single uniform exposure group despite substantial variations in age, comorbidities, and exposure characteristics, obscuring true drug effects and reducing generalizability across populations. • **Domain-Specific Gaps**: Clinical trial diversity deficits remain quantified but unaddressed; neuroimaging studies of older adults show divergent structural findings potentially attributable to participant and exposure heterogeneity; inflammatory and endocannabinoid physiology changes with age are rarely captured in young-skewed samples; psychosis-risk research remains concentrated in adolescents despite implications for older, newly-initiated users. **Dosage & Administration** Not reported. **Safety & Adverse Effects** Not reported. **Evidence Quality** This narrative review identifies a critical methodological problem rather than synthesizing outcome data. Limitations include reliance on observational characterization of existing literature rather than meta-analysis or systematic review methodology. The review's strength lies in highlighting the "Dual Diversity problem"—combining population underrepresentation with analytical approaches that suppress heterogeneity—across multiple research domains. The author provides concrete recommendations to address these gaps: population-benchmarked reporting standards, age-stratified enrollment modeled on International Council for Harmonisation (ICH) E7 guidelines for older populations, heterogeneity-preserving statistical analyses, and establishment of minimum exposure descriptor sets. The evidence quality reflects moderate-to-low certainty given the review's focus on identifying systematic bias rather than quantifying clinical outcomes. This work functions as a methodological critique calling for fundamental restructuring of cannabis research design and analysis approaches.

More recent cannabis research