Under the Hood

LSD Effects Are Similar To The First Stage Of Psychosis, Could Provide Model For Research

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LSD causes major changes in consciousness, but why? Pixabay Public Domain

Since its discovery, lysergic acid diethylamide (more commonly known as LSD) has been responsible for altering the consciousness of many people. Though scientists today have detailed knowledge of how the substance affects specific serotonin receptors, it’s unclear how these pharmacological effects translate into such a significant change in consciousness.

A new report presented at the annual conference of the American College of Neuropsychopharmacology in Hollywood, Fla., suggested that LSD reduces the connectivity within brain networks — basically, the extent to which neurons within a network can fire simultaneously. It also showed that LSD seems to reduce how much separate brain networks remain unique in their patterns or synchronization of firing.

Dr. Robin Carhart-Harris and his team at Imperial College London began their experiment with sequential brain scans on 20 volunteers, using fMRI to map changes in blood flow and changes in brain activity. They also utilized magnetoenchalography (MEG) to record the magnetic fields produced by electrical currents occurring in the brain, allowing them to image brain function. The technology showed that LSD led to a chaotic brain state not dissimilar to what is seen in a certain stage of psychosis. They observed neurons that in a normal state, would have fired together, fall out of synchronicity. They also saw networks that were normally distinct fall into overlapping patterns of connectivity.

The team found a potential explanation for the hallucinations and distortions that are so common in LSD intoxication — blood flow in the visual cortex at the back of the brain. The MEG picked up a change in brain oscillations as well, specifically a decrease in alpha waves across the brain. These changes were highly correlated with visual hallucinations, suggesting that while under the influence of LSD, “the visual system is tethered more to the internal than external world.”

LSD may be able to provide a helpful model of human psychosis, since it leads to changes in the brain network that overlap with the prodromal (the first) phase of psychosis.

“With better assessment tools available today than in the 1950s and 1960s, it may be possible to evaluate potential uses of LSD as a treatment for addiction and other disorders, such as treatment-resistant depression, which we are currently investigating with a similar drug to LSD,” Dr. Carhart-Harris said in a statement.

Source: Carhart Harris r, et al. The Re-Emergence of serotonergic Hallucinogens as Tools for Neuropsychopharmacology. Neuropsychopharmacology. 2015.

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