Tracing the relationship between marijuana and mental health

In the 1930s, there was a pot panic.

When the movie Reefer Madness came out in 1936, the criminalization of marijuana was already in the works. The film falls into the popular 1930s genre called “exploitation film.” Described by IMDB as a “cautionary tale”, the film describes a group of innocent teenagers who become addicted to “chill cigarettes”, with the blame falling squarely on three marijuana dealers. Drunken teenagers run over and kill a pedestrian, shoot and kill a classmate, and beat a man to death with a stick. In the end (spoiler alert!), the teenagers jump out of a window and die.

Nearly 100 years later, the story surrounding cannabis in the US has evolved, to say the least. As more research on marijuana is published, there is growing evidence that, rather than being a threat to society, cannabis – which is banned in most countries – has a host of potential benefits in the physical, neurological and psychiatric realms.

A little history of marijuana

A year after the release of Reefer Madness, the Marijuana Tax Act of 1937 was passed, essentially banning its recreational use. Three decades later, as part of Controlled Substances Act of 1970, the federal government classified marijuana as a substance with an “unacceptable medical use.” By the early 1980s, the anti-drug campaign “Just Say No” had consumed the American consciousness. Research shows that the number of Americans who consider drug abuse the nation’s “number one problem” has risen by about 60 percent between 1980 1989

Attitudes began to change in the early 21st century. Marijuana began to gain mainstream acceptance. A rapidly growing number of Americans have shifted from concerns about addiction and categorizing weed as a gateway drug to universal acceptance, or at least openness, to its medical benefits. In fact, as of last year, fewer than 1 in 10 U.S. adults (8 percent) believe marijuana should be illegal for all uses, according to a 2021 survey released by Pew Research. The same survey found that 91 percent of US adults said the substance should be legal for medical use, recreational use, or both.

Inconclusive association with mental health

According to Harvard Healththe most common use of medical marijuana in the US is for pain control, including nerve-based pain from conditions such as multiple sclerosis. Research shows that it can be useful in treating nausea and vomiting, a side effect of chemotherapy and forms of epilepsy.

What seems to be missing from the research annals, at least until recently, are studies that focus on the relationship between mental health and cannabis use. In 2017, the Institute on Alcohol and Drug Abuse at the University of Washington published a paper called “Marijuana’s Effects on Mental Health: Depression,” calling attention to the lack of scientific research on the mental health link.

“Mental health conditions feature prominently among the reasons for medical marijuana use, yet there is a paucity of rigorous, experimentally controlled studies examining marijuana’s effects on mental health conditions,” the paper’s authors write. There are early studies showing that cannabis use increases the risk of depression and vice versa.

But what is still missing today, according to 2021 study in Frontiers in Psychology, is a systematic study of the potential positive side effects of cannabis use, including reduced depression and anxiety. The researchers of this study aimed to synthesize all published research linking depression and cannabis, noting that it is “imperative to evaluate the consequences of subsequent increased consumption.” The work is becoming more important as the legalization of medical marijuana increases in the U.S. As of July, it was legal in 38 states and Washington

Emerging research

The The Mayo Clinic suggests there is a relationship between pain and depression—both potentially leading to the other. Now, a number of new studies suggest that cannabis may represent an alternative to recommended antidepressants as a means of relieving pain caused by anxiety and depression.

One 2018 study in Journal of Affective Disorders, which the authors called the first of its kind, suggests that smoking cannabis can significantly reduce short-term levels of depression, anxiety and stress. The study is considered unique because the researchers looked at the effects of inhaled cannabis used by participants in their own homes, rather than THC pills administered in a laboratory.

And 2020 study published in Yale Journal of Biology and Medicine suggests that the majority of study participants experienced at least a short-term antidepressant effect from cannabis use. The study authors also note that theirs is the largest study published to date measuring how different types of cannabis flowers (the most common type of product used in the US) affect depression-related symptoms in real time.

More recently, a study published in Frontiers in Psychiatry in 2021, a study found an association between cannabis use and lower self-reported depression. Users also report better sleep, better quality of life and less pain. Participants who started using cannabis products as part of the study reported a 25% reduction in depression symptoms.

Participants who had never started using cannabis during the study showed almost no change in symptoms, according to lead study author Erin Martin, Ph.D. candidate in the Department of Neurology at the Medical University of South Carolina. “This is important because the ‘initiators’ (as we call them in the paper) went from meeting criteria for ‘moderate’ depression to below the cutoff for a clinical diagnosis of depression,” says Martin, adding that further placebo-controlled studies on psychiatric utility of cannabis products needs to be done to confirm the team’s findings.

The importance of research

Statistics compiled by the National Institute of Mental Health (NIMH) suggest that more than 21 million American adults – about 8.4 percent of the US adult population – have suffered from at least one major depressive episode.

The NIMH defines a major depressive episode as “a period of at least two weeks when a person has experienced depressed mood or loss of interest or pleasure in daily activities and has had most defined symptoms, such as problems with sleep, eating, energy, concentration, or self-esteem.” “

The prevalence of major depressive episodes is highest among US adults aged 18 to 25 years. Additionally, the study found that 10.5 percent of the female population and 6.2 percent of the male population suffered from major depressive episodes.

Depression is also a global phenomenon. According to World Health Organization, 280 million people suffer from depression. That’s 3.8 percent of the world’s population, ranking depression among the world’s most debilitating medical conditions.

This reality about depression creates an urgency for more treatment options. While Martin notes that commonly prescribed antidepressants work well for many people, she stresses that “they still don’t work for everyone, and many can have debilitating side effects.” This dilemma compels her to continue studying the relationship between depression and cannabis: “If there’s an opportunity for cannabis to help people in the ways they need without causing a lot of harm, that’s definitely something worth exploring.”

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