Psychedelic users process emotional expressions differently than nonusers

People who regularly use psychedelic drugs outside of clinical settings appear to process emotional information differently than those who abstain. A recent brain imaging study found that experienced psychedelic consumers process threatening facial expressions more efficiently and display altered neural responses to various emotions. The research was published in the journal Human Brain Mapping.

Classic psychedelics like psilocybin mushrooms and lysergic acid diethylamide (LSD) profoundly alter sensory perception, mood, and self-awareness. In recent years, medical trials have reported that these substances might offer long-lasting psychological benefits. Patients in these medical trials often experience reduced symptoms of depression, decreased anxiety regarding terminal illness, and an increased ability to regulate their emotions. These clinical settings provide safe, highly controlled environments with psychological support to guide the patient through the intense acute drug experience.

The majority of psychedelic use worldwide happens outside of controlled laboratories. This naturalistic use involves variable doses, unpredictable environments, and differing personal motivations. Because these varied conditions can heavily influence the drug experience, researchers wanted to find out if the emotional benefits seen in strict clinical trials hold true for people using psychedelics in the real world.

Paweł Orłowski, a researcher at the Centre for Brain Research at Jagiellonian University in Poland, led the investigation. Orłowski and his colleagues, Aleksandra Domagalik and Michał Bola, aimed to map the brain activity of experienced psychedelic users and see how they react to everyday emotional triggers compared to people who have never taken the drugs.

The researchers started by surveying more than 2,500 individuals. From this large pool, they selected 33 experienced psychedelic users who reported taking the substances at least ten times in their lives. They paired this group with 34 nonusers who expressed a willingness to try psychedelics in the future.

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To isolate the specific effects of psychedelics, the research team matched the two groups based on several demographic and lifestyle factors. The users and nonusers were matched based on age, sex, education level, and the size of their home city. They were also matched for their history of meditation and their use of other psychoactive substances like alcohol, cannabis, and stimulants. All participants were required to abstain from using psychedelics for at least 30 days before the experiment.

To observe how the participants processed emotions, the researchers used functional magnetic resonance imaging. This technology measures blood flow in the brain to estimate which neural areas are most active at any given moment. While inside the brain scanner, participants completed a facial expression recognition task.

During the task, participants viewed a series of faces displaying anger, fear, happiness, or a neutral expression. Each image flashed on the screen for just a fraction of a second. The participants then used a button pad to identify the emotion they had just seen as quickly and accurately as possible.

The behavioral data produced a notable difference between the two cohorts. Psychedelic users correctly identified angry facial expressions faster and with a higher degree of accuracy than their nonuser counterparts. When it came to recognizing fearful, happy, or neutral faces, the performance of the two groups was remarkably similar.

The research team interpreted this high performance as a sign of enhanced processing efficiency for threat-related information. Often, encountering a threatening stimulus like an angry face triggers a brief freezing response that slows down cognitive reactions. The regular psychedelic users seemed to bypass this typical delay, processing the emotional information and pressing the correct button without hesitation or impulsive errors.

The brain scans supported these behavioral observations. When viewing angry faces, the psychedelic users registered lower activation in brain regions associated with raw emotional reactivity and threat detection. These areas included the insula and the supplementary motor area, which are typically engaged when a person is reacting to negative or alarming stimuli.

The opposite pattern emerged when participants looked at happy faces. In response to positive emotional expressions, the psychedelic users displayed heightened activity across various sensorimotor and parietal brain regions. These specific neural areas help process external sensory information and integrate bodily sensations, matching clinical reports of heightened positive moods following psychedelic therapy.

The researchers also focused their attention on areas of the brain that make up the default mode network. This brain network is typically highly active when a person is resting, daydreaming, or reflecting on their own internal thoughts. An overactive default mode network is often associated with the repetitive negative thinking seen in depressive disorders.

In certain regions of this network, nonusers showed very distinct, varied patterns of brain activation depending on which specific emotion they were viewing. They exerted heavy cognitive effort to process the negative emotions. By contrast, the psychedelic users exhibited a much flatter and less differentiated neural response across the different emotional categories.

The authors suggest this flattened response might fit into a concept known as predictive processing. This theory proposes that the brain constantly uses rigid expectations based on past experiences to navigate the world. These strong assumptions can sometimes force people into maladaptive defensive habits when they encounter a perceived threat.

Psychedelics are thought to relax these rigid expectations. This relaxation forces the brain to rely more heavily on raw sensory data coming in from the eyes and ears, rather than filtering the world through strict assumptions. By sidestepping heavy-handed mental filtering, psychedelic users might process defensive triggers like anger more smoothly and automatically.

One unexpected result involved the amygdala, a small structure deep inside the brain that acts as an alarm system for fear and negative emotions. Prior clinical trials often report that psychedelic therapy calms amygdala reactivity for days or weeks after a dosing session. Yet, this naturalistic study found that differences in amygdala activation between users and nonusers were not statistically significant.

The scientists offered a few explanations for this discrepancy. Because participants abstained from psychedelics for at least a month prior to the scan, it is possible that any biological calming effect on the amygdala is temporary and fades over several weeks. Alternatively, the specific type of brain scan sequence used in the setup might not have been sensitive enough to capture subtle changes in such a small, deep brain structure.

The study carries a few caveats that prevent definitive conclusions. Because it was a cross-sectional study capturing a single moment in time, it cannot prove that the psychedelic drugs caused the brain changes. It remains entirely possible that people who naturally possess a highly efficient style of emotional processing are simply more inclined to seek out and stick with psychedelic substances.

The sample also comes with an inherent self-selection bias. By choosing participants who had used psychedelics ten or more times, the researchers likely gathered a group of people who consistently enjoy the drugs. Individuals who had terrifying or uncomfortable early psychological experiences likely quit using them and would not have made it into the study cohort.

Future investigations will need to track people over a long period from before they start using psychedelics until well after they have established a naturalistic routine. Tracking brain scans over months or years could help scientists determine exactly how these potent substances alter emotional perception in the real world.

The study, “Investigating Emotional Reactivity in Experienced Users of Psychedelics: A Cross-Sectional fMRI Study”, was authored by Paweł Orłowski, Aleksandra Domagalik, and Michał Bola.