NOTICE: The editors of the Journal of Psychopharmacology retracted this systematic review and meta-analysis after the authors requested extensive revisions to fix incorrectly extracted data and modify the authorship list. The editors determined that these sweeping changes fundamentally undermined the reliability of the original findings, leading to a retraction that the authors opposed.
Recent studies have started uncovering the potential benefits of psychedelics on the brain, especially concerning cognitive and emotional health. A recent meta-analysis published in the Journal of Psychopharmacology has found that individuals who consume psychedelics exhibit significantly higher levels of brain-derived neurotrophic factor (BDNF) compared to healthy non-users. This increase in BDNF suggests that psychedelics might enhance the brain’s ability to adapt and reorganize itself, potentially offering new avenues for treating mental health disorders.
BDNF is a protein that plays a critical role in the health and functioning of the brain. It supports the survival of existing neurons and encourages the growth and differentiation of new neurons and synapses. BDNF is vital for long-term memory, learning, and the overall plasticity of the brain—its ability to change and adapt in response to new experiences.
Alterations in BDNF levels have been linked to various neuropsychiatric disorders, including depression, anxiety, and post-traumatic stress disorder. Higher levels of BDNF are generally associated with better cognitive function and mental health, making it a key area of interest for researchers studying the brain and its many functions.
The researchers conducted a meta-analysis on the relationship between psychedelics and BDNF levels to address a significant gap in the existing literature. While individual studies have explored the effects of psychedelics on neurotransmitter systems and immediate brain functions, the long-term molecular impacts, particularly concerning BDNF, are less understood.
By aggregating data from different studies, a meta-analysis can identify patterns, common findings, and potential discrepancies among the studies. This method increases the statistical power and improves the estimate of the effect size, making it easier to draw meaningful conclusions.
“My interest in this topic arises from the growing evidence that psychedelics significantly impact mental health,” said study author Arman Shafiee of the Alborz University of Medical Science.
The researchers followed stringent guidelines to conduct this meta-analysis, adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework. They registered their study protocol in the international database PROSPERO.
A comprehensive search was conducted across multiple databases, including Embase, Scopus, Web of Science, and PubMed, from their inception until July 9, 2023. The researchers used a broad range of keywords related to psychedelics and BDNF to ensure a thorough search. Only randomized clinical trials that evaluated changes in BDNF levels after psychedelic use were included. Observational studies, animal studies, and other non-relevant publications were excluded.
Out of an initial pool of 549 articles, nine studies met the inclusion criteria for this meta-analysis. These studies were published between 2019 and 2023 and conducted in Switzerland and Brazil. Most of these studies were of low risk of bias.
The meta-analysis confirmed that psychedelic users had significantly higher BDNF levels than non-users. The pooled standardized mean difference was 0.20, indicating a modest but statistically significant increase. Subgroup analyses showed that the increase in BDNF was more evident with certain psychedelics, particularly dimethyltryptamine (DMT). The results remained consistent across different sources of BDNF measurements, with plasma levels showing more robust evidence than serum levels.
Despite the promising findings, the study had several limitations. The sample sizes in the included studies were relatively small, ranging from 16 to 73, and the heterogeneity between studies could influence the results. Furthermore, variations in the duration of psychedelic use and the gender distribution among participants might have affected the findings.
Future research should aim to include larger and more diverse samples to provide more reliable evidence. Additionally, studies should consider both plasma and serum BDNF levels and explore potential differences in BDNF response between men and women. The researchers also noted the need for more randomized controlled trials to confirm the clinical efficacy and safety of psychedelics as therapeutic agents.
“Our findings suggest that psychedelics may increase BDNF levels, potentially enhancing neuroplasticity and improving mental health outcomes, indicating their potential as treatments for conditions like depression,” Shafiee told PsyPost. “However, more controlled clinical trials are necessary to establish causality, understand long-term effects, and evaluate the risks and safety of psychedelic use.”
The study, “The effect of psychedelics on the level of brain-derived neurotrophic factor: A systematic review and meta-analysis,” was authored by Arman Shafiee, Razman Arabzadeh Bahri, Mohammad Ali Rafiei, Fatemeh Esmaeilpur Abianeh, Parsa Razmara, Kyana Jafarabady, and Mohammad Javad Amini.