Age and Cannabis Co-Use Are Associated with Differences in Experience and Perceived Benefits of Psilocybin: A Retrospective Study.

Hooper J.; Williams S.; Mueller R.; Hutchison K. · Journal of psychoactive drugs · 2026

**Background & Methods** This cross-sectional retrospective study analyzed 365 current psilocybin users, stratified into three age groups (18-25, 26-54, 55-77 years), to examine how demographic and behavioral factors influence psilocybin experiences and outcomes. The study assessed acute experiences, psychological outcomes, and substance co-use patterns across the age spectrum. **Key Findings** • Age-related differences in acute effects: Younger participants (18-25) reported significantly more adverse experiences during psilocybin use, while older adults (55-77) experienced milder acute effects. However, age did not significantly impact mystical experiences, psychological insight, or overall psychological outcomes. • Cannabis co-use associations: Cannabis co-use with psilocybin was associated with greater perceived improvements in multiple domains, including quality of life, anxiety symptoms, depression, and alcohol abuse. This suggests potential synergistic effects between psilocybin and THC. • Polysubstance patterns by age: Younger adults demonstrated higher rates of nicotine co-use with psilocybin compared to other age groups, indicating distinct substance co-use patterns across the lifespan. **Dosage & Administration** Not reported. **Safety & Adverse Effects** Younger participants reported significantly more adverse experiences compared to middle-aged and older adults. Older adults experienced milder overall effects during acute psilocybin use. Specific adverse event types and severity ratings were not detailed in the abstract. **Evidence Quality** This study has notable limitations affecting evidence quality. As a retrospective cross-sectional design relying on participant recall, it is subject to recall bias and cannot establish causality. The lack of dosage standardization across participants, unstandardized outcome measures, and absence of control groups limit generalizability. Selection bias may affect results if current users differ systematically from former or never-users. The study provides correlational evidence only and cannot determine whether cannabis genuinely enhances psilocybin outcomes or if users perceiving greater benefits are more likely to report co-use. This represents low-to-moderate quality evidence (Level 3-4) suitable for hypothesis generation rather than clinical recommendations. The authors appropriately note the need for mechanistic investigation and controlled studies assessing polysubstance effects with psychedelics.

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