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Go to CuriosityStream.com/SciShowPsych  to start streaming thousands of documentaries  and nonfiction TV shows. [♪ INTRO] Humans have been eating  hallucinogenic, or “magic,” mushrooms in ritual and spiritual contexts  since at least 3,000 BCE. But despite how long we’ve  known about magic mushrooms, we actually barely know anything,  well, about magic mushrooms.

Or, more specifically, about psilocybin, the molecule that makes  these mushrooms so special. There’s over 200 species of  fungi that produce psilocybin, which makes them hallucinogenic. But this molecule itself isn’t the one  that causes hallucinations in humans.

You see, the body strips off a phosphate molecule from the psilocybin to form a  different molecule called psilocin. And it’s psilocin that actually  sends people on a trip, because it binds to one of the  same receptors as serotonin, which is the molecule involved  in things from sleep and blood pressure to mood regulation and depression. The receptor is 5HT2A, which  is also targeted by other psychedelic drugs like LSD, MDMA, and mescaline.

And scientists still don’t know  how or if molecules binding to the 5HT2A receptor result in hallucinations, but they think it’s related to how parts  of the brain communicate with each other. And a way they think that psilocybin  is doing this is by strengthening the connections between brain networks, even for areas that weren’t strongly  connected before taking psilocybin. In mice, for example, psilocybin may actually  be creating entirely new connections.

In people, psilocybin increases the strength  of the connections responsible for how you sense the world, while  also decreasing the connections responsible for how we understand  signals from our environment.   And some scientists think this mix and  match on how we sense and understand signals from our surroundings is what may cause an altered state of consciousness. One of the side effects of magic mushrooms. But right now, this research about  connectivity is still fuzzy and sometimes conflicting, in large part because research  into the effects of psilocybin is so new.

Policy changes in the last 10 to 15 years  have let researchers finally start studying not just the basic effects of psilocybin,  but also the possible therapeutic benefits. These studies typically involve giving  one or two moderate to high doses of psilocybin in the presence  of at least one psychiatrist. The idea is for the patient to  have a good trip experience, where the lines between themselves  and the world around them break down.

This lets them feel connected with the world. One of the areas of therapeutic interest is for people with treatment-resistant depression. This type of depression occurs in about 10  to 30 percent of people with depression, and it’s what it sounds like: people  whose depression either doesn’t respond or keeps coming back after they  start taking antidepressants.

In one early study, researchers treated  participants with treatment resistant depression and about two-thirds of them  responded to psilocybin one week after treatment, and 60 percent still showed improved depression scores three months later. Only a few studies have been done so far, but they seem to suggest that psilocybin  can improve depression scores pretty dramatically, and that there  are pretty large improvements when compared to a placebo. And compared to traditional  antidepressants, which require a daily dose, hallucinogens can show months  of benefit after just one.

It also seems like, when  it’s combined with therapy, psilocybin can be pretty good  at helping treat addiction too. So, researchers have looked at  alcohol and cigarette addiction also. And again, all of these  studies are pretty preliminary, but in a study of people with alcohol dependence, participants drank less  frequently and had fewer heavy drinking days for up to two months  after getting psilocybin treatment.   Which is less compared to just doing  traditional therapy once a week.

And for smoking cessation, one study  showed that 80 percent of participants were smoke-free after six months, and  60 percent were still smoke-free up to 57 months later, after just  two or three doses of psilocybin. That’s almost five years. But one big question for future  psychedelic research is whether it’s possible to get the benefits  without actually tripping.

So scientists looked into  microdosing, which involves regularly taking super-small doses of psychedelics, small enough not to trip, but enough  to feel a positive mood boost. And a team of researchers has been  exploring the possibility of a non-hallucinogenic psilocybin-like  molecule that also binds with the 5HT2A receptor that might give the  antidepressant benefits without the high. And while it might seem feasible to have  some of the good effects without the trip, other researchers aren’t sure that  tripless psychedelics will work as well.

That’s because there’s some evidence  that people with more intense tripping experiences have better therapeutic responses. On the other hand, getting the benefits  without the trip would be great, because while psilocybin is non-addictive  and really difficult to overdose on, there can still be side effects. Things like paranoia and anxiety while  tripping can put people at risk of physical harm, and sometimes, even more,  long-term psychological problems.

But it’s hard to really draw any firm  conclusions, because of the drug laws that make psilocybin hard to study, which means there just hasn’t been a lot of research done. And the studies that have been  done tend to be pretty small. Importantly, the clinical trials of psilocybin  that have been done involve having a therapist present for the entire trip, and  then more therapy in the days that follow.

But it seems that research on psilocybin  bodes a promising future, but only time will tell if it will go mainstream  as a formal therapeutic. If you would like to learn  more about the fungus among us you should check today’s sponsor Curiosity Stream. They’re a subscription streaming service  that offers thousands of documentaries and non­fiction TV shows from some  of the world's best filmmakers.

They even have a whole documentary on how fungi, which have been around since the dawn  of life, made our world as we know it. You can sign up for a whole year of  CuriosityStream for under fifteen bucks, so if you’re interested, you can get  started at CuriosityStream.com/SciShowPsych. [♪ OUTRO]