Psilocybin, a psychedelic substance found in some mushrooms (more than 200 species) has shown exciting potential in the treatment of depression. However, there are still some questions, such as what is the effect caused by it on the brain and how long the beneficial results shown in preliminary tests.
Evidence supporting the use of psychedelic drug psilocybin as a treatment for depression is growing, with a new study uncovering its long-term effects on the brain.
A new study by researchers at Yale University found that a single dose of psilocybin given to mice "induced an immediate and lasting increase in connections between neurons," according to a Yale News report. The research was published July 5 in the journal Neuron.
"We not only saw a 10% increase in the number of neuronal connections, but also they were on average about 10% larger, so the connections were stronger as well," said Yale's Alex Kwan, the paper's senior author and an associate professor of psychiatry and neuroscience.
Chronic stress and depression are known to reduce the number of these neuronal connections, the authors said.
Alex Kwan, associate professor of psychiatry and neuroscience and senior author of the paper, said, "it was a real surprise to see such lasting changes with just one dose of psilocybin," adding that "the new connections could be the structural changes the brain uses to store new experiences."
“We were studying the rapid-acting antidepressant ketamine, and found that it has various intriguing effects on changing neuronal connections in the brain. Then about two years ago, we started wondering if the effects generalize to other compounds, so we began working on psilocybin.”
The team used a laser-scanning microscope to image dendritic spines—small protrusions on nerve cells—in high resolution. The researchers then tracked the spines for multiple days in living mice and found that the number of dendritic spines and their size increased within 24 hours of the administration of psilocybin and were still present a month later. The mice that were subjected to stress also showed behavioural improvements and increased neurotransmitter activity after being given the psychedelic compound.
“Psychedelics like psilocybin can give mystical-like experiences and have exciting therapeutic potentials, but we still don’t know much about what they do to the brain. Here we study what psilocybin does in a mouse brain. The data suggest that there is a growth of new neuronal connections in mice after one dose of psilocybin. This happened in the frontal cortex, a brain region important for mood and cognition,” Kwan told.
“We know that the brain has many cell types. Here we study one type called the pyramidal neurons. For future studies, we have some ongoing projects to look at other cell types to see if they are also affected by psilocybin. Knowing what types of cells are impacted will be informative for developing new drugs that may then target those specific cell types.”
“Overall, the results demonstrate that psilocybin-evoked synaptic rewiring in the cortex is fast and enduring,” the authors wrote in the summary, “potentially providing a structural trace for the long-term integration of experiences and lasting beneficial actions.”
The study, “Psolocybin induces rapid and persistent growth of dentritic spines in frontal cortex in vivo”, was published by Ling-Xiao Shao, Clara Liao, Ian Gregg, Neil K. Savalia, Kristina Delagarza, and Alex C. Kwan. The findings are published today (July 5, 2021) in the journal Neuron.