Marijuana and Mental Health: What We Know, Harm vs. Benefit

Aug 22, 2022
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Marijuana and mental health leave a pile of unanswered questions. The most important question of marijuana’s effects on mental health are still out for debate. Does marijuana help or hurt mental health?

Marijuana and Mental Health: What We Know, Harm vs. Benefit

by Ashley Howell PMHNP

Marijuana and mental health leave a pile of unanswered questions. The most important question of marijuana’s effects on mental health are still out for debate. Does marijuana help or hurt mental health?

Marijuana, pot, weed, or cannabis all refer to the same thing. A commonly used substance which is thought of as both helpful and harmful. Pot is one of the most widely used psychoactive substances in the world, and is the most commonly used drug of abuse in the United States. It’s also a substance that tends to be used more frequently in patients with mental illness. Whether this is because people experiencing mental illness self medicate with pot or experience worsening mental health due to it. The relationship between marijuana and mental health is still a looming question.

Here’s What We Know About Marijuana and Mental Health

Marijuana is a complex substance

One reason that it’s difficult to determine whether or not marijuana helps or hurts mental health is that this plant provides over 500 chemical substances. Many of which we have not studied yet. We do know that the two most important substances are THC (delta-9-tetrahydrocannabinol) and CBD’s (cannabinoids). THC is the chemical responsible for the psychoactive effects of marijuana, while cannabinoids are the chemicals thought to have the greater beneficial mental health effects. CBD’s are also thought to help lessen certain effects of THC, such as intoxication, sedation, and tachycardia.

These are some of the effects to the Central Nervous System and cardiovascular system from THC vs CBD







Muscle Relaxant



Pain relief















Increased heart rate



Decrease heart rate



Changes in Today’s Marijuana

Increased THC

A common point of discussion when looking at mental health and marijuana is the fact that marijuana nowadays is completely different from the marijuana earlier generations used. In 1995 the average THC content as at 4%, whereas today’s average THC is about 15% and can be as high as 34%. As we’ll discuss later, this doesn’t even include the strength of concentrates, which range in potency 70% THC to over 90%.

Several studies point to an antidepressant effect of THC at certain doses only. These studies found that there was a sweet spot for antidepressant effects from THC; too little and there was no benefit, too much and depression worsened. This likelihood is further complicated by the variation in THC strengths and amount ingested by the end user. While THC may have some highly desirable antidepressant effects, it would be hard for the average person to find the ideal dose.

This is further complicated by the fact that while THC may help decrease depression, it has been shown to worsen anxiety. So, someone using pot to treat their depression may end up worsening their anxiety. Quite often, people experience both anxiety and depression at the same time. With one issue covering the others intensity, this is a fact that often goes unexamined when looking at marijuana and mental health.

The ratio of THC to CBD has dropped significantly

As previously discussed, CBD has been found to offset some of the negative side effects of THC, or provide beneficial effects. This  includes things like CBD’s ability to decrease anxiety and psychosis. CBD also helps prevent the increase in heart rate caused by THC. This racing heart rate has been known to cause more than one period of anxiety while under the effects of THC.

Today’s marijuana has been shown to be decreasing in CBD, while increasing in THC. This effect is amplified in many concentrates, vape oils, and edibles as they often use distilled THC as the base ingredient. The skewed ratio of THC to CBD may be contributing to incidences of increased anxiety or psychosis in heavy marijuana users. This fact may be one of the most important regarding marijuana and mental health.

Use and daily use are increasing

We have also seen a trend in increased use of marijuana, as well as increased daily use. Use of marijuana in the general population has increased from 10.4% to 13.3% in the time spanning 2002 to 20015. Daily or near daily use has also increased from 1.9% of adults to 3.5% of adults from 2002 to 2014. This finding was even more significant in people with depression. In 2017, 18.64% of depressed people use marijuana frequently versus 8.67% of the population using marijuana daily or near daily. While the question of marijuana and mental health may be unanswered, we do know that use and frequency of use are increasing.

Frequent and heavy use may be to blame for the potential problems

Due to legalization and decriminalization of marijuana in the past decade, there has been many conversations about marijuana and mental health. Marijuana use, particularly in daily use, can worsen some mental health symptoms. In some states, they are considering adding a warning label to products due to the increase in psychosis or worsening mental health symptoms of depression or anxiety(1). Some long-time users of Marijuana products may disagree, considering marijuana to be “harmless,” or “its just a plant.” It’s important to recognize the difference in THC or other marijuana products commonly used today. Due to genetic modification, THC products have become more potent than ever before with some THC content up to 90-100%.

Concentrates may be harmful

Concentrated THC products have been linked to psychosis, and addiction. Due to the concentrated levels of THC, marijuana use has been known to cause psychosis in patients who have not experienced this before. Psychosis is a state of disorientation during which the person has a hard time understanding what is real, often experiencing hallucination and paranoia. Moreover, chronic marijuana has been linked to depression, social anxiety and suicidal thoughts.

Marijuana's Effects on Emotional Regulation

A lesser, but still problematic side effect of chronic use of marijuana products is emotional dysregulation. This is caused by decreased neural activity. The part of the brain that is affected by THC products is called the prefrontal cortex. This part of your brain is responsible for attention, impulse control, cognitive flexibility, and memory. Additionally, chronic use of marijuana products can slow your brain’s ability to accurately and swiftly process emotional states which can lead to issues within relationships. This stress could lead one to use more marijuana products to cope with the distress.

Marijuana use in teenagers is especially concerning as their brain is still developing, particularly the prefrontal cortex mentioned above. There are some links between use of marijuana at a young age and the development of schizophrenia.

Marijuana and Schizophrenia

As we previously stated, THC concentrates can cause acute psychosis. Research also shows that earlier, higher, and more frequent doses of cannabis and most likely THC increases the risk of psychotic illness. This risk is increased as much as 5 times in the frequent cannabis user. Early cannabis use can also contribute to worsening cognition or thinking ability for users. Imaging studies show that first episode schizophrenia patients with a history of cannabis use showed greater loss of brain matter.

Marijuana in Moderation

Marijuana in moderation is probably fine and has shown to have some mental health benefits. However, it's important to understand that the line between "moderation" and "excess" is still a fuzzy one, especially considering the higher potency and ubiquity of marijuana products today. As with all medications and supplements, results may vary due to individual gene variations and how little we know about how marijuana interacts with other medications.

What's important is, to be honest with your mental health provider about your use of marijuana products. As a mental health provider practicing in the state of Colorado, I can assure you that the vast majority of our patients are cannabis users, and none of them are judged by me or my colleagues. But it's important we know just how much you are using so that we can help you to feel better and be safe. Be sure to include that information so that you can get the best mental health care you can!


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