This month, the city of Dever Colorado made the landmark decision to decriminalize psilocybin mushrooms. It’s the first U.S. city to do so. More famously known as “magic mushrooms” these intoxicating yet non-addictive fungi grow naturally throughout most of the United States. And yet, psilocybin and psilocin have been illegal in the country since 1969, when the use of psychedelic drugs became widespread in consumer culture.

In Denver, the initiative to decriminalize passed with a narrow margin—50.6 percent of voters approved the bill. Dubbed Initiative 301, the bill makes the personal possession of magic mushrooms among those 21 and older one of the lowest law enforcement priorities. The bill also prevents city authorities from spending money on resources dedicated to prosecuting or pursuing criminal charges against adults who possess or consume the mushrooms.

The recent change not only makes Denver the most psychedelic-friendly city in the United States, but it also represents a major shift in cultural, political, and even medicinal views on mind-altering plants and other natural products. Westerners have found themselves amidst a revived psychedelic therapies renaissance, a renaissance supported by a new wave of scientific research.

A New Psychedelic Renaissance (Yet Again)

This unique time period in Western culture has recently been dubbed the second psychedelic renaissance. All jokes comparing modern-day millennials and free-loving hippies aside, the “second psychedelic renaissance” is, in reality, far from the second. Back in the 1960s and 70s, psychedelics were first introduced to a consumer-focused capitalist culture. Yet, the use of mind-altering plants and periods of intense social drug consumption have dotted history books for generations.

Take, for example, the mid-1800s when European elites had their first taste of hashish. The habit was originally picked up by French soldiers in Egypt, who brought the compressed cannabis resin home with them after the French invasions led by Napoleon Bonaparte. The almost hallucinogenic experiences the hashish provided lead to a slight cultural obsession with hallucinogens among those who could afford the substances, and novelists like the great popularized the hallucinogenic experience through their writings.

As early as 1729, Chinese Emperor Yung Chen issued the first rulings criminalizing the recreational use of opium. While opium is not a hallucinogen, a growing culture of recreational drug use and addiction originally propagated by Portuguese imports of the plant into China inspired Chinese leadership to continue to crack down on opium trade over the next three centuries. It is important to mention, however, that unlike psychedelic drugs, narcotics such as opium come with a high risk of addiction.

These are simply examples from the last three hundred years. And yet, if archeological evidence is any indication, human civilizations across the globe have always had some sort of relationship with psychoactive substances — just recently, archeological researchers in Bolivia found evidence of a 1,000-year-old pouch that contained traces of five different psychoactive plants.

The tradition of medical cannabis consumption in China is thought to date as far back as 2,737 BC when mystical Emporer Shen-Neng is believed to have introduced cannabis and many other plants into medical practice. Shen-Neng is believed to be the father of traditional Chinese medicine, although the medicinal uses of cannabis in China were not recorded until the first or second century A.D.

More recently, however, this old tradition has been reintroduced to Western scientific practice. After medical researchers took a brief hiatus from psychedelic research during the late 70s, through the early 90s, psychiatrists and other medical professionals are once again exploring the opportunities of these unusual and transformative therapies.

For the city of Denver, greater tolerance for psilocybin may provide the first of many long steps toward decreasing barriers for researchers and other psychedelic proponents who hope to develop the medical and spiritual legitimacy of the psychoactive experience.

The Vast Potential of Psychedelic Therapies

The most profound implications of psychedelic medicine lie in the arena of mental health. In 2016, the first magnetic resonance imaging (MRI) scans provided glimpses into the brain on LSD. Colloquially known as “acid”, LSD is considered a classical psychedelic capable of radically altering cognition and cultivating feelings of harmony and oneness with the universe.

When put under the MRI machine, the brains of those on LSD did something magnificent — they lit up, nearly all the way up. Normally, when the human brain processes visual imagery, very specific regions of the brain activate. These regions are the visual cortex and the visual association areas that normally process information taken in by the eyes.

After an injection of LSD, however, brain scans revealed that networks across the entire organ were activated, linking portions of the brain that do not typically fire together. The psychoactive truly inspired a whole-brain experience. According to the leading scientists on the experiment, those that were given LSD were “seeing with their eyes shut.”

Brain scans of the effects of psilocybin extracted from mushrooms have made similar findings. In 2014, research published in the Journal of the Royal Society Interface used functional magnetic resonance imaging (FMRI) to map the effects of the psychoactive substance on communication pathways between various processing networks in the brain.

Similar to the LSD study, the brains of patients given psilocybin were extra-active. The psychotropic compound caused a marked increase in connections between various networks, transforming normal pathways into a super-highway system with dense web-like construction.

Psychedelics, it would seem, encourage a unique explosion of brain activity that links up previously remote pockets of the mind. This mind-melting may have long-lasting positive effects to boot—research suggests that the “mystical-type” experiences inspired by psilocybin provided some of the most meaningful moments of spiritual significance in the lives of study participants.

Depression

Some of the most groundbreaking research in psychedelic therapies are occurring in the arena of depression. A handful of trials have examined the potential of psychotropic therapies in depression in patients with life-threatening illnesses, yet hallucinogenic therapies may be useful in treatment-resistant depression as well.

In 2017, for example, researchers from Imperial College London found that psilocybin seemed to press the brain “reset” button in patients with clinical depression. The study found that after taking the psychedelic, activation of brain regions responsible for fear and anxiety became less active. Further, the brain’s “default mode”, so to speak, became more stable after treatment.

Obsessive Compulsive Disorder

Back in 2006, a study published in the Journal of Clinical Psychiatry found that psilocybin was effective in reducing the acute symptoms of obsessive-compulsive disorder. The study, however, only included nine total participants. More recently, however, a clinical trial of psilocybin for OCD is underway at Yale University and the Heffter Research Institute. The trial contains 30 active participants, although the final results will not be published until 2022.

Addiction

Research from 2014 and 2015 tested the effects of psilocybin therapies in patients suffering from tobacco and alcohol addiction. The studies, which were conducted as proof-of-concept trials, found that treatment with the psychoactive compound decreased cravings for alcohol and nicotine for several months after administration. Alcohol cravings were reduced for up to 36 weeks after a psilocybin treatment. Tobacco cravings were also significantly diminished after six months of treatment.

End-of-Life Psychological Distress and Anxiety

Several human studies on psilocybin have been conducted in patients with depression and anxiety associated with life-threatening cancer diagnoses. In one 2016 study published in the Journal of Psychopharmacology, psilocybin inspired positive changes in mood, depression, and anxiety levels in cancer patients six months after treatment with the psychoactive. An improved mood, however, wasn’t the only benefit reported by the patients. 80 percent of study participants also reported improvements in quality of life, spiritual satisfaction, and improved life meaning.