A single dose of psilocybin, the psychedelic compound found in so-called magic mushrooms, may leave measurable changes in the brain that can still be detected a month later.
A new study suggests these changes may help explain why the drug has attracted attention as a possible treatment for depression and other mental health conditions.
Psilocybin is a natural compound found in certain mushrooms. It changes the way the brain works for several hours, creating changes in perception, emotions, and thinking. In recent years, scientists have become interested in whether these temporary experiences might also lead to lasting improvements in mental health.
Earlier studies have suggested that psilocybin may help some people with depression, anxiety, addiction, and emotional distress when it is used in carefully supervised medical settings. However, researchers have not fully understood how one short psychedelic experience could produce benefits that last for weeks or even months.
To investigate this question, researchers from the University of California, San Francisco, and Imperial College London studied 28 healthy adults who had never used a psychedelic before. None of the volunteers had a diagnosed mental illness, allowing the team to focus on how psilocybin affects the healthy brain.
The study was carefully designed. Participants first received a 1-milligram dose, which acted as a placebo because it was too small to produce strong psychedelic effects. Brain activity and psychological health were measured before and after this session.
About one month later, the same volunteers received a 25-milligram dose that produced a full psychedelic experience. Researchers monitored brain activity with EEG during the experience and later used MRI-based brain scans to examine possible longer-term changes.
The scientists paid close attention to something called brain entropy. In simple terms, brain entropy describes how varied and flexible brain activity becomes. Higher entropy means the brain is exploring a wider range of activity instead of following its usual patterns.
Within about an hour after the larger dose, brain entropy increased noticeably. The volunteers also described powerful changes in awareness and thinking. Nearly every participant said it was the most unusual state of consciousness they had ever experienced.
The day after taking psilocybin, participants reported much greater psychological insight than after the placebo session. People who gained the greatest insight also tended to report better well-being two and four weeks later.
Brain scans performed one month later suggested there were still measurable differences in the brain’s communication pathways. The researchers stressed that these findings need further investigation, but they may indicate that psilocybin temporarily encourages the brain to reorganize itself in ways that last beyond the psychedelic experience.
The volunteers also performed better on tests of cognitive flexibility one month later. This ability helps people adjust to changing situations, consider new ideas, and break away from rigid thinking patterns. Scientists believe this flexibility may be one reason psilocybin has shown promise for treating several mental health conditions.
The researchers concluded that the psychedelic experience itself appears to be an important part of the treatment process rather than simply a side effect. Greater changes in brain activity were linked to stronger feelings of personal insight, which in turn were linked to better well-being weeks later.
The study was published in Nature Communications. Although the results are encouraging, the researchers emphasized that this was a small study involving healthy volunteers rather than patients with mental illness. Larger clinical trials are still needed before firm conclusions can be made about medical treatment.
Overall, the study provides important clues about how psilocybin may work rather than proving it is a treatment on its own. The combination of brain measurements, psychological testing, and follow-up assessments strengthens the findings, but the small number of healthy participants means the results should be interpreted carefully.
Future studies in larger groups of patients will be needed to determine whether these lasting brain changes translate into safe and effective therapies.
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Source: University of California, San Francisco.
