Can Psilocybin Treat Depression?

Doctor Rhonda Patrick here. Today, we're going to talk about psilocybin. Psilocybin is a compound produced by certain types of mushrooms. These mushrooms, often called magic mushrooms due to their psychoactive effects, have been used by humans for thousands of years, often for ceremonial purposes. Now, modern medicine shows that psilocybin may have therapeutic benefits for clinical depression. Researchers first began studying psilocybin in the 1950s, when. When it showed promise even back then as a therapeutic drug for several mental health conditions. But psilocybin use was banned during the 1970s, which meant it was incredibly difficult for scientists to continue their research. It wasn't until several decades later that researchers were able to start investigating it again.

In many ways, the progress since then has been a bit of a psychedelic renaissance, this time a little bit closer to the standards expected of mainstream science. The effects of psilocybin on our brain are complex. The effect most people may be familiar with is its distinctive auditory and visual hallucinations it causes when ingested. Scientists think psilocybin does this primarily by interacting with receptors in the brain, particularly in the thalamus, a region of the brain that processes sensory information from our environment, things we see, touch and hear. It decreases thalamic activity, causing sensory alterations or hallucinations. Psilocybin also seems to have positive effects in treating mood disorders like depression.

In one small study involving adults who had depression, researchers at the Johns Hopkins School of Medicine found that after just two doses of psilocybin combined with psychotherapy, half of the study participants achieved remission of their depressive symptoms for at least one month. A few years ago, I had the privilege of speaking with the senior author of this study, Dr. Roland Griffiths, a professor of psychiatry at Johns Hopkins. When discussing a previous study, he explained the clinical protocol his team uses and some of the qualities of the experiences that he believes may underlie the antidepressant effects of psilocybin.

And so, one of the first studies that we've conducted looking at therapeutic effects is to look at cancer patients who are experiencing very significant anxiety or fear in face of a life threatening cancer diagnosis. And it turns out that this kind of very disquieting existential anxiety and sometimes depression very often accompanies these life threatening cancer diagnoses, as you might expect that it would. On the session day, they take a capsule. This is synthesized psilocybin, it's not mushrooms. And they're invited to lay down on this couch with eye shades and headphones, through which they listen to a program of music and then they're invited to direct their attention inward on their inner experience. So this isn't a guided session.

There are two people present here who just provide reassurance if it's needed, but really are there just for safety purposes and to make people feel that if anxiety or fear arises, that they can just be reassured that despite what they may be feeling, they're going to be back to consensual reality by the end of the day. So this is the context, and it's very hard to pin down the specific nature of the experience because it can be really quite varied. The central feature is this sense of the interconnectedness of all people and things. It's a sense of unity, and that's accompanied by a sense of sacredness or reverence for that experience.

There's something humbling about that experience and also very important, the experience has authenticity to it, a truth value to it that people will often say it's more real and more true than everyday waking consciousness. And interestingly, these people experienced very large and sustained decreases in anxiety and depression. And those effects occurred really quite promptly after the administration of the drug. And although the design of the study was such, it was a crossover design. So people were crossed over between essentially an inactive dose of psilocybin to an active dose, or vice versa.

So the strongest conclusion we can make comparing our placebo condition and our active condition is this effect lasted out to five weeks, but in fact, we followed people out to six months and there was no evidence that there was any significant rate of relapse over that period of time. So, in other words, most people who demonstrated a large therapeutic effect remained having low levels of anxiety or depression out to six months. So there's suggestive evidence that there's a long duration of. After one treatment. After one treatment, yeah. Several other small studies have also shown psilocybin to be beneficial in reducing symptoms of depression. And in one study from the Imperial College London has gone even further.

This small study concluded that psilocybin treatment, combined again with psychotherapy, produced similar results compared to traditional SSRI antidepressant treatments. But these are small, early stage clinical trials and much more investigation will be needed as clinical research continues. It's still poorly understood how or why psilocybin works in the brain to counteract depression. But in a recent study from Yale University, researchers attempted to answer this question. They found psilocybin creates new and lasting connections in the brain, or at least in mouse brains. In this study, researchers examined the neurons in the animal's frontal cortex, which is a part of the brain implicated in higher level cognition, memory and decision making.

You can think of a neuron like a tree with a trunk, roots and branches with leaves. Neurons receive electrical input from other cells through their dendritic spines and pass along electrical signals to other cells through their axons. This connection is called the synapse. In particular, the researchers were focused on the animal's dendritic spines. That's because these tiny membrane protrusions may be significant for those suffering from depression. Though we're still not entirely sure why people become depressed, researchers believe the condition may be associated with low synapse density in certain areas of the brain.

This makes researchers think there may be a link between dendritic spine density and depression and that potentially by increasing spine formation we we might be able to combat depression. So back to the mice. After the researchers gave them a psilocybin dose, they studied their brains to see what happened. They found that the single dose of psilocybin increased the formation of new dendritic spines, a 12% increase a week after exposure. And some of these new connection sites were still there a month after the mouse's psilocybin dose.

The researchers also noted that psilocybin improved stress related behavior in the mice and it promoted excitatory neurotransmission, meaning it increased neuron activity in the brain, which combated the decrease in neurotransmission seen when mice were subjected to chronic stress. This research only shows how psilocybin affected mice, but it's still another step in understanding how this compound works in the brains of humans. Though there is one clinical study showing that psilocybin does seem as effective as SSRIs. In the short term, we need more research to fully understand how psilocybin works against mental illness. We also need to learn more about why depression occurs and how it affects our brains before we can truly figure out how to combat it.

One particular area I hope to see converge is what role psychedelics may also play as immunomodulators, even as a secondary effect, particularly in light of what we know about the role of inflammation in eliciting symptoms of depression. There's still a lot to uncover on this topic. Research on the role of psilocybin as a depression treatment is still in its infancy. It does not yet meet the standard needed by modern medicine to be called a bona fide treatment for clinical depression. Will that change? Only time will tell. I'm Dr. Rhonda Patrick and I'll catch you next time.