Study Finds Evidence of ‘Reverse Spin Bias’ in Medical Cannabis Research

OG article by Sarah Sinclair

January 29, 2026

A peer-reviewed paper in Research Integrity and Peer Review identifies “reverse spin bias” in medical cannabis research, where authors downplay or dismiss statistically significant beneficial findings despite supporting evidence. Unlike traditional spin (exaggerating non-significant results), this involves undervaluing positives in systematic reviews, often without justification—seen in e-cigarette and cannabis pain studies. Researchers analyzed 29 reviews on medical cannabis for pain; 10 showed reverse spin, framing evidence as “inconsistent” or low-quality to avoid recommendations. Mechanisms include discounting data, omitting findings, discrediting studies, invoking unsubstantiated future harms, and emphasizing risks unrelated to the review. Authors suggest it aids publication in journals assuming cannabis harms only. Drug Science’s Hannah Barnett notes it reinforces stigma, delays harm reduction, and skews policy by making norm-driven decisions seem evidence-based. The bias could affect other contested treatments like safe opioid sites. Calls for editors and reviewers to scrutinize discrepancies between findings and conclusions to ensure accurate, balanced reporting and truly evidence-informed practice.