Fraudulent studies are undermining the reliability of systematic reviews: on the prevalence of problematic images in preclinical depression studies

Systematic reviews are considered by many to constitute the highest level of scientific evidence. However, the methods used in a systematic review for combining information from multiple studies are predicated on all of the reports being truthful. For a systematic review of preclinical studies of depression, we found that potentially fraudulent studies—studies featuring problematic images suggestive of gross error or manipulation—were both common and capable of biasing our findings. The prevalence of problematic studies (we had concerns with 19% of all studies with images) and our inability to find a simple pattern for identifying them undermine systematic reviews within our research field. We suspect that this is symptomatic of a broader problem that needs immediate addressing.