The revival of psilocybin between scientific excitement, evidence of efficacy, and real-world challenges.

The revival of psilocybin in psychopharmacological research heralds a potential paradigm shift for treating mood and anxiety disorders, and other psychiatric conditions beyond the psychotic spectrum. This critical review evaluates current evidence on psilocybin's efficacy, juxtaposing potential benefits with the practical aspects of psychedelic-assisted psychotherapy (PAP) and the methodological constraints of existing research.An electronic literature search was conducted using PubMed/MEDLINE, selecting studies published up to December 2023 that explored the clinical use of psilocybin in mood and anxiety disorders, obsessive-compulsive disorder, post-traumatic stress disorder, and substance use disorder. Despite promising preliminary results suggesting psilocybin's efficacy in alleviating depression and anxiety, as well as obsessions, compulsions, and addictive behaviors, significant evidence gaps persist. These include evaluating the efficacy of psilocybin compared to standard antidepressants or anxiolytic molecules and identifying patient subpopulations that might benefit most from PAP. Concerns about psilocybin's safety, long-term efficacy, and optimal dosage remain unclear due to previous trials' limitations. Real-world implementation faces challenges, including infrastructural requirements, personnel training, and unresolved legal and ethical issues. This paper argues for further research to substantiate the evidence base, emphasizing the need for larger studies that overcome current methodological limitations and explore psilocybin's full therapeutic potential. While psilocybin holds promise for psychiatry, its successful translation from research to clinical practice demands more robust evidence on efficacy, safety, and methodological rigor. In addition, other factors, such as cultural stigma and legal/ethical issues, need to be successfully addressed to facilitate psilocybin's implementation in healthcare systems.