Brain waves predict the intensity of magic mushroom trips

A person’s natural brain wave patterns might offer a reliable preview of how intensely they will react to a dose of psilocybin. The resting electrical activity of the brain not only shifts dramatically during a psychedelic experience, but specific patterns present before taking the drug actively predict the psychological effects that follow. The research was published in Progress in Neuropsychopharmacology & Biological Psychiatry.

The active ingredient in magic mushrooms, psilocybin, is currently under intense investigation as a presumed therapeutic agent. Clinical trials are testing its efficacy for depression, addictive disorders, and post-traumatic stress disorder. Australia recently approved the drug for treatment-resistant depression in specific clinical settings.

Despite this clinical momentum, the exact ways the compound alters human brain function remain somewhat elusive. A major challenge in modern psychiatry is figuring out why people respond so differently to psychedelics. Finding a reliable way to anticipate these diverse patient reactions could help doctors identify which individuals are most likely to benefit from the therapy.

To investigate this, a team of researchers led by scientist Cheng-Teng Ip at the University of Macau centered their attention on analyzing the brain’s electrical signals. They wanted to see if specific electrical changes correspond to the intense perceptual shifts people experience while under the influence. By mapping these internal signals, the team hoped to find a measurable biological marker that relates to the emotional and psychological outcomes of the drug.

The researchers used an electroencephalogram, or EEG, which involves placing small sensors on the scalp to detect electrical activity. Brainwaves are classified by their frequency, measured in hertz. Low-frequency waves like delta and theta occur during deep relaxation and sleep.

Slightly faster alpha waves are typically dominant when a person is resting quietly with their eyes closed. Fast brainwaves, including beta and gamma waves, generally dominate the brain during periods of high alertness, cognitive effort, and intense concentration. By isolating these different bands, scientists can observe distinct modes of neural operation.

Researchers are particularly interested in a brain system called the default mode network. This network consists of several interacting brain regions that are highly active when a person is resting and daydreaming, but relatively quiet during focused tasks. Prior imaging studies point to this exact network as a primary target for psychedelic compounds.

The study involved twenty-five healthy adult volunteers, consisting of eighteen men and seven women with an average age of twenty-four. The investigators used a double-blind, placebo-controlled, crossover design. This means each participant attended two separate sessions, receiving either a precisely measured capsule of psilocybin or a placebo on varying days.

Neither the participants nor the staff handing out the capsules knew which one was being given at any specific time. During each session, researchers recorded the participants’ resting brain activity for ten minutes before administering the capsule. They then took another ten-minute recording sixty minutes after the subjects ingested the capsule.

This post-administration recording was timed to capture the brain’s state right as the physiological effects peaked. The participants kept their eyes closed for five minutes of the recording and open for the other five, with the researchers focused entirely on analyzing the eyes-closed data. Once the recordings were complete, specialized software translated the surface electrical signals into a three-dimensional map of the brain’s gray matter.

After the drug effects subsided, participants completed an extensive survey known as the Altered States of Consciousness Questionnaire. The survey asks individuals to rate their feelings along five primary dimensions. One dimension tracks feelings of deep unity, spiritual connection, and blissful mood.

Another dimension evaluates less pleasant sensations, like the frightening feeling of losing one’s identity and suffering from acute anxiety. The remaining dimensions measure visual distortions, auditory alterations, and the degree to which a person feels their overall vigilance and attention have been artificially reduced.

When analyzing the brainwave data, Ip and his colleagues found robust electrical differences between the active drug and placebo sessions. Under the influence of the psychedelic, participants experienced a marked decrease in the power of slow-frequency brainwaves. At the same time, the power of their fast-frequency beta and gamma waves increased broadly across the cerebral cortex.

This shift diverges from the typical electrical progression of the resting brain. Usually, when a person sits with their eyes closed, their brain produces rhythmic, slow alpha waves. The psychedelic compound appeared to interrupt this natural progression toward physiological relaxation. Instead, the brain produced rapid waves normally associated with processing new information, even though the participants were just resting in a quiet room.

The researchers suggest these fast gamma waves might be part of the active brain mechanics that generate the hallucinations and profound shifts in self-perception. When comparing the brainwave changes to the survey results, the team found broad positive correlations. The stronger the increase in fast brainwave activity across the temporal and limbic regions of the brain, the more intensely the volunteers rated their subjective experiences.

Feelings of cosmic unity and positive mood mapped closely to increased high-frequency activity in parts of the brain associated with memory and emotion. In contrast, anxiety and the frightening sensation of losing one’s identity were associated with increased activity in the visual processing centers at the back of the brain.

The team also examined how brain regions were communicating with each other. They observed increased connectivity within the default mode network during the psychedelic state. The connections between different nodes of this network grew stronger, especially in the higher-frequency ranges, indicating that the drug forces these distinct brain areas into tight synchronization.

Perhaps the most highly anticipated finding involved the baseline brain scans taken before anyone swallowed a pill. The researchers found that higher levels of fast brainwave activity in the frontal cortex before taking the drug predicted an intense psychological experience later on. The frontal cortex handles complex cognitive processing, abstract thinking, and future planning.

In addition, low baseline activity in certain memory-related regions also predicted stronger subsequent sensations of ego dissolution and vivid visual changes. The researchers propose that a person’s baseline state of cognitive and emotional readiness fundamentally shapes the depth of their psychological response to the compound.

A few technical limitations apply to this research. The study tracked a relatively small group of twenty-five people. Small sample sizes restrict the statistical power of an analysis and limit how broadly the results can be generalized to the wider public. Replicating the experiment with a larger group will help verify the consistency of these detected patterns.

Additionally, the experiment only enrolled healthy volunteers without psychiatric conditions. The brain wave dynamics of healthy individuals may operate differently than those of people experiencing severe depression or trauma. Researchers do not yet know if the brainwave predictions seen here will function the exact same way in clinical populations.

Future studies will need to test if these specific resting brainwave patterns can predict how well a patient responds to guided therapy. If they do, doctors could scan a patient before starting treatment to see if they possess the optimal brainwave profile for a successful psychiatric outcome. This would help medical professionals allocate resource-intensive psychedelic treatments to the patients most likely to experience a true therapeutic benefit.

The study, “Psilocybin-induced alterations in EEG power, connectivity and network dynamics in healthy subjects: Correlations with subjective experience and implications for therapeutic applications,” was authored by Cheng-Teng Ip, Sebastian Olbrich, Mateo de Bardeci, Anna Monn, Andres Ort, John W. Smallridge, and Franz Vollenweider.