Marijuana and mental illness

Marijuana is easier than ever to access — 11 states (including California) and the District of Columbia have legalized recreational use for adults older than age 21, and 22 more states have legalized medicinal marijuana.

Although the drug has been approved for medicinal use in many places, research is still ongoing to determine its therapeutic benefits. In fact, some research shows a connection between marijuana use and early onset of psychiatric disorders, particularly in those genetically predisposed to mental illness.

While there is no evidence that marijuana actually causes mental illness, it has been shown to worsen symptoms in those living with psychiatric conditions. Marijuana has the immediate effects of inducing paranoia and anxiety. Subtle effects of reduced motivation and depressed mood may not be as obvious.

Marijuana and psychiatric medications
The marijuana of today is much more potent than what was available in decades past, and its mind-altering effects can cause people to experience intense panic and anxiety, even if they are not living with mental illness. However, for those living with psychiatric conditions — especially those managing their condition with medication — the effects can be much worse.

“There has always been a known association with marijuana use and severe psychiatric illness. For instance, people with psychotic disorders like schizophrenia have some kind of substance abuse disorder about 50% of the time,” says psychiatrist Dr. Brian Miller, clinical director at Sharp Grossmont Hospital’s Behavioral Health Center. “In the past, we didn’t know if the relationship was causal, but increasing evidence has shown substance abuse, including marijuana, can provoke or exacerbate psychiatric illness.”

How marijuana affects the brain
Marijuana binds to cannabinoid receptors in the brain to produce a variety of effects including euphoria, intoxication, and memory and motor impairment. These cannabinoid receptors are critical for brain development and are part of the endocannabinoid system, impacting the formation of brain circuits important for decision-making, mood and responses to stress. Higher doses of THC — the psychoactive ingredient in marijuana — are more likely to produce anxiety, agitation, paranoia and psychosis.

“Marijuana is similar to alcohol, nicotine and caffeine in that all of these substances are widely used for the pleasant and rewarding effects,” explains Dr. Miller. “However, there are risks of overuse, addiction and complicating factors. As the amount and frequency a person uses goes up, so does the chance they will suffer adverse consequences.”

Impact of increased use
While it is difficult to measure the widespread effects of the legalization of marijuana, there has been a clear effect on emergency room visits for the acute adverse effects of the drug. New users particularly may not appreciate the potent mind-altering effects and may develop intense panic and dysphoria. There has been a general but misguided attitude that if it’s legal, it can’t be too bad, resulting in more people trying marijuana for the first time.

“Despite being legal, marijuana is not a benign substance,” says Dr. Miller. “Some people will choose to use marijuana similarly to alcohol or other mood-altering substances. However, just as someone with an alcohol use disorder should refrain from drinking, many with preexisting psychiatric disorders should avoid marijuana entirely.”