12 Psychoactive Plants And What They Do To Your Brain, According To Science

Without plants, it's safe to say that human history would be pretty radically different. Not only have plants helped provide things like basic nutrients to help the human body function, evolve, and survive, but humans have found a myriad of uses for plants over the thousands and thousands of years of their co-existence.

The Ancient Egyptians used the Lavandula or lavender plant to scent perfumes and for various ointments, and the Ancient Romans included the salvia officinalis or sage plant into their hair care routines, as well as in various medicines for many different ailments. The first known use of plants by humans for their intoxicating and psychoactive properties dates back to 13,000 years in the Levant, when the Natufian civilization made alcoholic beer from a combination of seven different plants. Psychoactive plants are those that affect the mind if they are properly ingested, and depending on the specific plant, their psychoactive properties induce unique responses in the brain.

For the most part, psychoactive plants contain chemicals that affect different neurotransmitters like serotonin, dopamine, and cannabinoid receptors, which are responsible for things like stimulation, sedation, altered moods, and even hallucinations. Today, plants still play a crucial role in many people's lives, and people use their psychoactive properties for both recreational and medicinal reasons.

If you or anyone you know needs help with addiction issues, help is available. Visit the Substance Abuse and Mental Health Services Administration website or contact SAMHSA's National Helpline at 1-800-662-HELP (4357).

Of all the psychoactive plants on earth, tobacco is definitely one of the most popular and widely used in modern human history. Tobacco contains the psychoactive drug known as nicotine, which is extremely addictive for the user. There are two primary types of tobacco that growers plant today for their nicotine content, Nicotiana Tabacum and Nicotiana Rustica, and they are from the Solanaceae or nightshade family of plants. The most popular ingestion methods of tobacco are smoking the dried leaves as cigarettes, sniffing the leaves as snuff, or using chewing tobacco.

Inside the brain, nicotine primarily affects the nicotinic acetylcholine receptors (nAChRs), which are responsible for controlling neurotransmitters like acetylcholine, dopamine, and serotonin. Nicotine makes its way to the brain as quickly as 10 seconds after inhalation when smoking, and users report experiencing feelings like relaxation and increased focus, which scientists think is due to the acetylcholine reaction. 

In addition, it might sound surprising, but nicotine can actually enhance cognitive function related to things like working memory and fine motor skills. This is why it can be so hard for users to quit, as the withdrawal from nicotine causes them to experience a feeling of cognitive decline, which can only be rectified by more nicotine. Unfortunately, there is also strong evidence that adolescent smokers are more likely to develop psychiatric and cognitive defects when they get older from nicotine's effect on the brain (via Cold Spring Harbor Perspectives in Medicine).

For hundreds of years, humans have used the Salvia Divinorum plant for religious, spiritual, and medical reasons. The plant is native to Oaxaca, Mexico in the Sierra Madre Oriental mountain range, where for many years the only users were the indigenous Mazatec people. Since the mid-20th century, its use has spread throughout the world, and it is a popular recreational drug today. Users of Salvia ingest the plant through smoking or otherwise orally consuming the leaves, and they report vivid visual hallucinations fierce enough to cause out-of-body experiences as well as synesthesia– or experiencing multiple senses at once, like the ability to feel sound. The "high" from Salvia only lasts a maximum of about 20 minutes but is noted for being extremely intense.

The psychoactive compound inside Salvia is known as Salvinorin-A. Salvinorin-A targets the kappa-opioid receptor (KOR) in the brain, and scientists think the powerful reactions are related to its high dosage and unique KOR interaction (via the International Journal of Neuropsychopharmacology). This is different than other common hallucinogens, like LSD and psilocybin, which target different serotonin receptors to produce their effects. Salvinorin-A's interaction with the KOR is much different and is the only known substance to act this way, except possibly Ibogaine. Additionally, Salvinorin-A also produces strong dissociative feelings in users.

Salvia is not thought to be linked to substance use disorders according to current criteria or many adverse health effects. Still, many users have wound up in the emergency room after particularly intense experiences or "trips."

While most people probably do not recognize the Psychotria Viridis bush native to the Amazon Rainforest, some of them may be familiar with its potent psychoactive drug known as DMT. For thousands of years, Shamans in the Amazon have been combining the Psychotria Viridis bush with the Banisteriopsis Caapi vine to create the psychedelic concoction widely known as Ayahuasca. Shamans use Ayahuasca in ceremonies celebrating everything from the spiritual and religious to the medicinal.

Like other psychedelics such as mescaline, DMT targets the 5-HT2A, 5-HT2C, and 5-HT1C serotonin receptors in the brain to produce its hallucinogenic effects (via Theresa M. Carbonaro in "Neuropharmacology of N,N-Dimethyltryptamine"). It also stimulates other neurotransmitters, like dopamine and acetylcholine, but it largely works by activating the 5-HT serotonin response. Unlike other psychedelics, DMT is not orally active by itself. That's why Shamans use the caapi vine, because the vine contains specific alkaloids that stop the body from destroying the DMT as it is digested, allowing it to work. In addition to DMT, Ayahuasca also contains the drugs 5-MeO-DMT and 5-OH-DMT, which also target the same neurotransmitters and produce similar hallucinogenic effects.

Another interesting facet of DMT is that it is found naturally occurring in the human brain in low concentrations, but scientists have little idea how it works. Some speculate that its release may play a part in how the mind perceives altered states of consciousness, like dreaming or near-death experiences, but that is far from conclusive and only speculative.

As the precursor to some of the world's most widely used licit and illicit substances, the opium poppy has a pretty controversial reputation. While it is helpful in many medications, it is also very mentally and physically addictive. There are both naturally derived opiates, like heroin and oxycodone, and synthetically derived opiates, like fentanyl and methadone, and the synthetic opiates can be much more powerful on the brain.

The scientific name for the opium poppy is Papaver Somniferum, and though it originated in Asia, people now cultivate it worldwide. The two biggest psychoactive drugs in the opium poppy are morphine and codeine, both of which have extreme suppressive effects. There are distinct opioid receptors throughout the body, mainly in the brain and spinal cord, which opiates interact with. These receptors work by reducing the amount of pain the user feels, and they also slow breathing and curb coughing. In addition, many users also experience euphoria and an altered state of consciousness that some describe as dreamlike. 

Some of the opioid receptors, specifically the mu-opioid receptors, are associated with the brain's reward system, and they release dopamine to reinforce positive life behaviors, like eating (via Addiction Science and Clinical Practice). This can lead to addictive behaviors associated with opiates, as taking them can stimulate these receptors, causing the brain to associate good feelings with opiate intoxication and develop a dependence. In addition, prolonged usage can change the brain so that it needs a continued opiate supply to retain normal function.

The Iboga plant, or Tabernanthe Iboga, is a very unique shrub, in that consuming it produces both intoxicating and anti-addictive feelings in the user. The Iboga plant is indigenous to West Central Africa, and its important psychoactive drug is called Ibogaine. Users who ingest Ibogaine report having hallucinations similar to psychedelic drugs like LSD. Though scientists are not entirely certain, they think that the hallucinogenic properties are related to Ibogaine's interaction with the kappa-opioid (KOR) and 5-HT2A receptors in the brain, which is also how other hallucinogens like salvia and Mescaline work (via "Progress in Brain Research: Psychedelic Neuroscience").

However, what makes Iboga unique among all of these is that it also seems to impart anti-addictive emotions to some users, though scientists are still debating why. Some suggest that the intake of ibogaine reduces dopamine levels in the brain and that it can also reverse neuropathways relating to addiction, leaving them in a "pre-addiction condition." This means that users' brains won't default to wanting and relying on drugs to function, because newly developed neuropathways will push them in different directions. 

Many users report that after an Ibogaine trip or experience, their affinity for wanting to use other drugs decreases, sometimes for several months. This is reinforced by some animal studies showing similar reactions towards cocaine and opiates after ingesting Ibogaine, too (via Brain Research Bulletin). While it's far too early to call ibogaine any sort of addiction cure, it certainly has some interesting properties.