psilocybin – NIH Director's Blog (original) (raw)
Mapping Psilocybin’s Brain Effects to Explore Potential for Treating Mental Health Disorders
Posted on August 15th, 2024 by Dr. Monica M. Bertagnolli
Credit: Donny Bliss/NIH
Psilocybin is a natural ingredient found in “magic mushrooms.” A single dose of this psychedelic can distort a person’s perception of time and space, as well as their sense of self, for hours. It can also trigger strong emotions, ranging from euphoria to fear. While psilocybin comes with health risks and isn’t recommended for recreational use, there’s growing evidence that—under the right conditions—its effects on the brain might be harnessed in the future to help treat substance use disorders or mental illnesses.
To explore this potential, it will be important to understand how psilocybin exerts its effects on the human brain. Now, a study in Nature supported in part by NIH has taken a step in this direction, using functional brain mapping in healthy adults before, during, and after taking psilocybin to visualize its impact. While earlier studies in animals suggested that psilocybin makes key brain areas more adaptable or “plastic,” this new research aims to clarify changes in the function of larger brain networks and their connection to the experiences people have with this psychedelic drug.
In the study, the team led by Joshua Siegel, Nico Dosenbach and Ginger Nicol, Washington University School of Medicine in St. Louis, recruited seven healthy adults to take, in separate sessions, a high dose of psilocybin and the stimulant methylphenidate, the generic form of Ritalin, under controlled conditions. Because taking psilocybin comes with a risk for having disturbing or negative experiences, a pair of trained experts stayed with each participant throughout the sessions to provide guidance and support. They also helped participants prepare for and process the experience afterwards.
To visually capture the impact of psilocybin on the brain, the researchers had each participant undergo an average of 18 functional MRI brain scan visits. Four of the study’s participants also returned six to 12 months later to take an additional psilocybin dose. Comparisons of the brain images revealed profound and widespread, but temporary, changes to the brain’s functional networks. While an individual’s functional brain network is typically as distinctive as a fingerprint, psilocybin made the participants’ brain networks look so similar in the scans that the researchers couldn’t tell them apart. In addition, by following the brain scans with specialized questionnaires given to elicit details about participants’ subjective experiences with psilocybin, the researchers were able to generate precise data on each person’s unique impressions and associated changes in their brain networks.
For all the participants, psilocybin desynchronized the brain’s default mode network, an interconnected set of brain areas that are most active when people are daydreaming or otherwise not engaged in any focused, goal-directed mental activity. By comparison, the default mode network remained stable after study participants took methylphenidate. Once the effects of psilocybin wore off, brain function returned almost to its original state. However, the researchers did note small but potentially important differences in each participant’s brain scans after taking psilocybin that remained for weeks.
The researchers suggest that the short-term changes in the default mode network likely explain psilocybin’s psychedelic effects, including the way it changes the way a person thinks about themselves in relation to other people and the world. They also suggest that the more subtle, longer-term effects they observed might indicate that the brain is more flexible in the weeks following a dose of psilocybin in ways that could allow for a healthier state. This may help explain preliminary research showing that psilocybin may have benefits for treating substance use disorders, as well as depression, anxiety, and other mental health conditions.
Though these findings are encouraging, they should not be seen as a reason to try psilocybin without clinician supervision or use it to self-medicate. The drug is not proven or approved as a treatment for any condition, and its unsupervised use comes with serious risks. The researchers hope that with much more clinical study of how and why this drug affects individuals in the powerful ways that it does, this kind of research may one day lead to a greater understanding of the human brain and promising new interventions that improve mental health.
Reference:
Siegel JS, et al. Psilocybin desynchronizes the human brain. Nature. DOI: 10.1038/s41586-024-07624-5 (2024).
NIH Support: National Institute of Mental Health, National Institute on Drug Abuse, National Institute of Neurological Disorders and Stroke
Tags: anxiety, brain, default mode network, depression, imaging, mental health disorders, neuroscience, psilocybin, psychedelic, substance use disorders