New research provides evidence that the active ingredient in so-called magic mushrooms can affect brain processes related to emotional functioning long after the substance has left one’s body. The findings, published in Scientific Reports, shed new light on the long-term effects of psilocybin.

Rather than examining the brain while it’s under the influence of psilocybin, the researchers from Johns Hopkins University School of Medicine were interested in the enduring impact of the substance.

“Nearly all psychedelic imaging studies have been conducted during acute effects of psychedelic drugs. While acute effects of psychedelics on the brain are of course incredibly interesting, the enduring effects of psychedelic drugs on brain function have great untapped value in helping us to understand more about the brain, affect, and the treatment of psychiatric disorders,” said Frederick S. Barrett (@FredBarrettPhD), an assistant professor and the corresponding author of the study.

In the study, 12 volunteers received a single administration of a high dose of psilocybin. One day before, one week after, and one month after psilocybin administration, the volunteers completed three different tasks to assess the processing of emotional information (specifically, facial expressions) while the researchers used magnetic resonance imaging to record their brain activity. During these three sessions, the volunteers also completed various surveys about their emotional functioning.

The researchers found that self-reported emotional distress was reduced one week after psilocybin administration, but returned to baseline levels at one month after psilocybin administration. Barrett and his colleagues also observed decreases in amygdala responses to emotional information one week after psilocybin administration, but this also returned to normal at one month post-psilocybin.

In addition, the researchers found increases in resting-state functional connectivity, which measures how blood oxygen level-dependent signals are coordinated across the brain, at both one week and one month after psilocybin administration.

“A single high dose of psilocybin, administered to properly screened individuals in a carefully controlled setting, can have lasting positive effects on emotional functioning in healthy individuals. These effects were reflected in transient changes in the function of brain regions that support emotional processing,” Barrett told PsyPost.

Because of the small sample size and lack of a control group, however, the findings should be considered preliminary.

“This study needs to be replicated in a larger sample with proper experimental controls, and we need to determine whether psilocybin exerts the observed effects by directly acting on emotional brain circuits, or by acting on brain circuits that control attention and cognition that may have down-stream effects on emotional brain circuits,” Barrett explained.

The study, “Emotions and brain function are altered up to one month after a single high dose of psilocybin“, was authored by Frederick S. Barrett, Manoj K. Doss, Nathan D. Sepeda, James J. Pekar, and Roland R. Griffiths.