Weed and Depression: Does Marijuana Make for Depressed Brains?

The connection between alcohol use and mental health disorders like depression is pretty well-understood. Pot? Not so much. And that is somewhat problematic. As marijuana becomes increasingly destigmatized, not to mention decriminalized, in much of the country, understanding its association with mental health is more important than ever. Medical marijuana advocates even claim that certain strains of pot can be used as treatments for depression. What does the science have to say?

Not a lot. While there is substantive evidence that pot increases the risk of psychotic disorders such as schizophrenia, the link to depression is unclear. "If there is an association, the data are not as robust as with psychotic illness. It's just conjecture," says Dr. Eric C. Strain, director of the Center for Substance Abuse Treatment and Research and professor of psychiatry and behavioral sciences at Johns Hopkins.

[See: Am I Just Sad -- or Actually Depressed?]

Compare that stance with alcohol. "Alcohol is an extreme depressant, and the combination of alcohol and depression is a very malignant condition," says Dr. Andrew Saxon, chair of the American Psychiatric Association's Council on Addiction Psychiatry. "From my clinical experience, alcohol is worse than marijuana," says Saxon, who is also a professor in the department of psychiatry and behavioral sciences and director of the Addiction Psychiatry Residency Program at the University of Washington.

That doesn't mean pot and depression are benign partners, though.

Good, Bad or Indifferent?

There is evidence of a toxic relationship between the two. A 2017 study published in the journal Addiction found that teenagers who suffered chronic depression were more likely to develop marijuana-use disorder later in life.

But there is also evidence of pot helping with some symptoms of depression. A 2015 study out of the University at Buffalo's Research Institute on Addictions, for example, studied chronic stress and depression and the relationship with endocannabinoids, naturally occurring brain chemicals that are similar to chemicals in marijuana. "Chronic stress is one of the major causes of depression," said senior research scientist Samir Haj-Dahmane in a university press release. "Using compounds derived from cannabis -- marijuana -- to restore normal endocannabinoid function could potentially help stabilize moods and ease depression." Before you run out and get your medical marijuana card, however, note that this research was conducted on animals, and "there is still a long way to go before we know whether this can be effective in humans," Haj-Dahmane said.

And there is evidence that pot neither helps nor harms depression sufferers. A study published by the American Psychological Association reported that chronic marijuana use by teenage boys was not linked to later physical or mental health issues such as depression, psychotic symptoms or asthma. "What we found was a little surprising," says lead researcher Jordan Bechtold, a psychology research fellow at the University of Pittsburgh Medical Center. "There were no differences in any of the mental or physical health outcomes that we measured regardless of the amount or frequency of marijuana used during adolescence."

The country's leading medical organizations are similarly conflicted. "There is still a lot to learn about whether marijuana use may lead to mental health problems or if having a mental illness makes people more likely to use marijuana," the Centers for Disease Control and Prevention says. "Marijuana use has also been linked with depression and anxiety, and with suicidal thoughts among teens. However, it is not known whether this is a causal relationship or simply an association."

The National Institute on Drug Abuse notes that several studies have linked marijuana use to increased risk for psychiatric disorders, including depression, "but whether and to what extent it actually causes these conditions is not always easy to determine." NIDA looked at long-term data that examined associations between marijuana use, mood and anxiety disorders, and substance use disorders, and concluded that: "After adjusting for various confounding factors, no association between marijuana use and mood and anxiety disorders was found."

[See: 14 Ways Alcohol Affects the Aging Process.]

Experts Agree: Pot May Not Hurt, But Doesn't Help

Despite this confusion, few in the medical establishment think it's a good idea to mix pot with depression. The American Psychiatric Association is clear on this: "There is currently no scientific evidence to support the use of marijuana as an effective treatment for any psychiatric illness," it says in a position statement.

Practitioners tend to agree. "I don't see marijuana as harmful, but it will probably interfere with someone's ability to recover from depression," Saxon says. Though it is not considered a depressant, pot does tend to be sedating. That can promote social isolation or lack of social interaction, says Strain, "and I am not sure those are good steps for a person who is depressed. If it makes you more socially withdrawn ... that is not a good combination."

Saxon empathizes with depressed individuals who turn to mood-altering substances. "Depression is an utterly miserable condition to suffer from. I completely understand that someone who is not getting formal treatment or is a poor responder to the treatments we have might try anything to alter their state of consciousness," he says. "But there is no evidence marijuana will help. They should seek out treatment from a mental health professional. My best advice is not to be using marijuana."

[See: How to Find the Best Mental Health Professional for You.]

And it needs to be stated that pot use is in a contradictory statutory limbo at the moment, illegal from the Federal standpoint, legal in various modes (medical, recreational) in some states but not all of them. "We are in this very strange era right now," Strain says. Added together, all this information leads him to the same conclusion as most other mental health experts: "My counsel is, if they ask, 'Should I try smoking pot?' I discourage that. If someone is depressed and smoking pot, they should stop. I am very clear about that."

David Levine is a freelance health reporter at U.S. News. He is a contributing writer for athenaInsight.com and Wainscot Health Media, a former health care columnist for Governing magazine and a regular contributor to many other health and wellness publications. He also writes about lifestyle and general interest topics, from history and business to beer and baseball, as a contributing writer for Westchester, Hudson Valley and 914INC magazines. His work has appeared in The New York Times, Sports Illustrated, American Heritage and dozens of other national publications, and he is the author or co-author of six books on sports. You can connect him on LinkedIn.