Cannabis—referred to by its many names of marijuana, pot, weed, etc—is a psychoactive drug derived from the cannabis plant. Its relationship to mental health is deeply complex, as it can help some people while harming others. As the drug is legalized in more places, particularly in the U.S., the mental health implications will become increasingly important to observe, understand, and address.
Marijuana and Mental Health
For centuries, people have used marijuana for mental health reasons. Some people benefit from cannabis use, as it helps them feel calm, fall asleep, or relieve their pain, among other benefits. However, other people—especially those who start using cannabis early and those who use heavily and frequently—the drug exacerbates mental health problems or, in some cases, gives rise to new disorders.
Research has long documented a connection between cannabis and psychosis. Yet the connection is complex: Does cannabis cause psychosis? Are people with psychosis more likely to use cannabis? Do genetics underpin both cannabis use and psychosis? Recent studies have been teasing apart these threads and discovering that cannabis elevates the risk of psychosis.
Those with a higher risk of developing psychosis include daily cannabis users, people who use cannabis with high concentrations of THC, and those with a family history of psychosis.
It should be noted that this experience is relatively rare; many people who try or use marijuana don’t develop psychosis. However, THC concentrations have been increasing and cannabis has been legalized in more places, which may lead rates to rise.
Cannabis Use Disorder
Most people who use marijuana do not become addicted to it. However, the drug can be addictive, especially for frequent, heavy users. An addiction to marijuana is called Cannabis Use Disorder (CUD), and it is a diagnosis in the DSM-5.
Many people smoke cannabis without becoming dependent on it. However, research suggests that 13 percent of people who try cannabis even once by age 14 eventually develop an addiction . Among those who use cannabis regularly, between one-fifth and one-third develop CUD.
An addiction to marijuana may be becoming more common, because concentrations of THC have increased substantially over time. Research shows that higher concentrations of THC lead to higher rates of addiction and mental health problems; higher-potency marijuana may be four times more addictive than lower-potency marijuana.
A colloquial way to think about the hallmarks of cannabis use disorder are through the three Cs: cravings (a strong desire to use the drug), consequences (negative consequences of use), and loss of control (continuing to use despite the consequences). Tolerance and withdrawal are two key criteria as well.
The Science of Cannabis
Cannabis is comprised of two components: tetrahydrocannabinol (THC), the psychoactive component, and cannabidiol (CBD) which is not psychoactive. Marijuana produces effects on the brain by activating cannabinoid receptors, which in turn activate the brain’s reward system.
Cannabis is surprisingly diverse—it is categorized as a depressant, a stimulant , and a hallucinogen due to the wide variety of effects it can produce. (It is not classified as an opiate.) Cannabis can slow brain functions and lead to relaxation and sleepiness, as depressants do, but it can also speed up brain functions and lead to anxiety or paranoia, like stimulants, and lead to altered perceptual experiences, like hallucinogens.
Scientists don’t have a complete understanding of what happens in the brain during a high, but the process involves the brain’s reward pathways. A recent neuroimaging study examined the effects of THC in healthy young adults with a limited history of cannabis use. Subjects who received THC demonstrated greater connectivity between two regions in the reward system—the right nucleus accumbens and the medial prefrontal cortex. The higher subjects rated themselves, the greater the connectivity. The THC in cannabis may stimulate cannabinoid receptors on GABA neurons, turning off the continuous inhibition of dopamine and leaving users feeling a euphoric high.
Does cannabis prevent weight gain or induce weight loss?
Explore More About Cannabis
For a comprehensive understanding of cannabis, read our complete guide: