The Psychological Impacts and Message Features of Health Misinformation A Systematic Review of Randomized Controlled Trials

What does health misinformation look like, and what is its impact? We conducted a systematic review of 45 articles containing 64 randomized controlled trials (RCTs; N = 37,552) on the impact of health misinformation on behaviors and their psychological antecedents. We applied a planetary health perspective by framing environmental issues as human health issues and focusing on misinformation about diseases, vaccination, medication, nutrition, tobacco consumption, and climate change. We found that in 49% of the cases exposure to health misinformation damaged the psychological antecedents of behaviors such as knowledge, attitudes, or behavioral intentions. No RCTs evaluated the impact of exposure to misinformation on direct measures of health or pro-environmental behaviors (e.g., vaccination), and few studies explored the impact of misinformation on feelings, social norms, and trust. Most misinformation was based on logical fallacies, conspiracy theories, or fake experts. RCTs evaluating the impact of impossible expectations and cherry-picking are scarce. Most research focused on healthy adult US populations and used online samples. Future RCTs can build on our analysis and address the knowledge gaps we identified.