What topics does this cannabis study cover?

This study covers research on: THC, Mental Health.

Where was this research published?

Published in European addiction research on October 16, 2026.

In a Swiss 18-month study, THC exposure—not purchase volume—tracked with…

Q: What did this research study find?

**Overall quality of life remained stable** from baseline to 18 months; the reported mean change was not statistically significant.

THC Exposure, Not Cannabis Quantity, Predicts Quality of Life Outcomes: An 18-Month Longitudinal Study of Regulated Cannabis Access in Switzerland.

European addiction research • October 16, 2026 • Highly Relevant

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AI Summary

This 18-month observational study followed 300 people with regulated cannabis access in Switzerland to ask whether cannabis use was associated with changes in quality of life. Participants completed the EQ-5D at the start and follow-up, while pharmacy purchases, THC content, self-reported consumption, and problematic-use scores were tracked or assessed. Overall quality of life remained stable; the average change was small and not statistically significant.

In regression analyses, higher cumulative THC exposure, higher baseline CUDIT-R scores, and increased self-reported consumption each predicted lower quality of life at follow-up. By contrast, the total quantity purchased through regulated channels was not a significant predictor. These findings describe associations, not proof that cannabis exposure caused quality-of-life changes. This abstract-based summary is limited by the information provided: it cannot establish causation or determine the clinical importance of the associations.

💡 Key Findings

Overall quality of life remained stable from baseline to 18 months; the reported mean change was not statistically significant.

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Higher cumulative THC exposure, higher baseline problematic-use scores, and increased self-reported consumption each independently predicted lower quality of life at follow-up.

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Total cannabis quantity purchased did not significantly predict quality-of-life outcomes.

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📄 Original Abstract

INTRODUCTION: Despite widespread cannabis use, longitudinal evidence on quality-of-life impacts remains limited, particularly in regulated access contexts with objective purchase tracking. METHODS: We conducted an 18-month longitudinal analysis of 300 participants in the [ANONYMIZED] study, a regulated cannabis access study in Switzerland. Quality of life was assessed using the EQ-5D at baseline and 18 months. Cannabis consumption was tracked objectively through pharmacy-based purchases, with additional measures of tetrahydrocannabinol (THC) content, self-reported problematic cannabis use (CUDIT-R), and self-reported consumption amount. Multiple regression analyses examined predictors of quality-of-life outcomes. RESULTS: Overall quality of life remained stable from baseline (M=0.92, SD=0.18) to 18-month follow-up (mean change = 0.002, p=0.418). However, specific consumption patterns significantly predicted outcomes. Higher cumulative THC exposure over 18 months (b=-0.003, p=0.048), higher baseline CUDIT-R scores (b=-0.001, p=0.030), and increased self-reported consumption amount (b=-0.016, p=0.004) all independently predicted lower quality of life at follow-up. Notably, total cannabis quantity purchased through regulated channels did not predict outcomes (p=0.134). CONCLUSIONS: While regulated cannabis access does not lead to overall quality of life deterioration, THC exposure and consumption intensity-rather than absolute cannabis quantity purchased-are key determinants of wellbeing outcomes. These findings have important implications for harm reduction strategies and regulatory frameworks, suggesting that cannabis potency and use patterns matter more than total consumption amounts for long-term quality of life.