LSD Dulls Fear Response in the Brain

Swiss scientists have discovered that taking LSD reduces the activity of brain regions responsible for fear. The study was published in Translational Psychiatry.

Comparing the Effects of LSD and Placebo

LSD, or lysergic acid diethylamide, is the world’s most well-known psychedelic. Its effects are linked to its similarity to serotonin receptors, which it can activate, leading to increased dopamine levels in the brain. Scientists have suggested that LSD could be used to treat various mental health disorders. In tests with terminal cancer patients, LSD was found to reduce anxiety, pain, and depression. However, after a wave of interest in psychoactive substances, many countries completely banned LSD for any use, including medical. Only in recent years have some countries begun to relax their policies on psychoactive substances.

In 2008, Switzerland allowed research into the therapeutic use of LSD for the first time in 35 years. Researchers at the University of Basel took advantage of this opportunity.

How the Study Was Conducted

The scientists used functional magnetic resonance imaging (fMRI) to study how LSD affects the neural processes responsible for fear. The experiment involved 20 participants aged 25 to 38 (19 of whom were researchers themselves). Only two had previously tried psychedelics, and only once each. Participants received either a placebo (mannitol) or a dose of 120 micrograms of LSD. The main test was conducted six hours after taking the substance, when the effects peak, and lasted six minutes.

During the test, researchers monitored brain activity while showing participants 60 images of faces with varying degrees of fearful expressions. Images of calm faces were used as a control.

Key Findings

The main focus was on the amygdala, which is often hyperactive in anxiety disorders, as well as the fusiform and medial frontal gyri, which respond to fearful images in such tests. The results showed that LSD significantly reduced the response of these brain structures to fearful images. In particular, the reaction of the left amygdala, part of the brain’s serotonergic system, was much less pronounced. The response of the prefrontal cortex, which is involved in forming emotions, was also greatly reduced. As a result, participants who took LSD showed almost no fear response during the experiment.