IS MARIJUANA GOOD FOR DEPRESSION?

Guest post by Dr. Erik Messamore, Johnny’s Ambassadors Scientific Advisory Board

A NATURAL QUESTION

Marijuana can provide a sense of happiness and relaxation for many users, so some people with depression may consider marijuana a way to treat their depression symptoms (Cuttler et al., 2018). Research has shown that marijuana use is twice as prevalent in people with depression (Pacek et al., 2017), and as many as one-quarter of men with depression use marijuana daily (Lapham et al., 2017).

A natural question might be: can marijuana provide meaningful treatment for depression? While the effects of marijuana on the brain are not well studied in a clinical setting, people have been asking this question for decades and it is a common question in my psychiatric practice. In this article, I will examine what scientific literature has been able to determine so far about the relationship between marijuana use and depression.

CAN MARIJUANA TREAT DEPRESSION?

In 1845, researcher Dr. Jaques-Joseph Moreau famously conducted the first clinical study investigating the possible benefits of marijuana use for depression. A similar study was conducted in 1973, during a time when marijuana use was growing in popularity and many wondered about its usefulness as a treatment (Kotin et al., 1973).

Unfortunately, evidence from these two studies and others show that there is no clear, long-lasting, positive impact on depression symptoms from marijuana use. Participants in the study may have experienced a temporary mood boost, but 25% also experienced an increase in severe anxiety and many reported that their depression symptoms returned after use.

“One of the effects of hashish that struck me most forcibly…is that feeling of gaiety and joy…I saw in it a means of effectively combatting the fixed ideas of depressives…Were my conjectures mistaken? I am led to believe so.”

Dr. Jacques-Joseph Moreau, 1845

CAN MARIJUANA WORSEN DEPRESSION?

While studies have not shown evidence that marijuana is good for improving depression, it’s important to also ask if marijuana can worsen depression symptoms.

Several long-term mood surveys of marijuana users have built upon the conclusions of Moreau and Kotin, finding that 25% of marijuana users report depression as a side effect (Green et al., 2003, Cuttler et al., 2018). These surveys show again that while users may experience short-term relief, depression symptoms continued or even got worse over time.

Furthermore, a scientific literature review analyzing the association between cannabis use and depression in long-term studies found that the risk of receiving a depression diagnosis increased by 17% for those who used any amount of cannabis and by 62% for those who used cannabis weekly or more (Lev-Ran et al., 2014). This is not to say that one necessarily directly causes the other, but it does show that a higher risk of depression is associated with higher cannabis use.

So, in short, marijuana users might experience some short-term relief from depression symptoms but over time their symptoms can worsen, suggesting that cannabis use for most people is either an ineffective treatment against depression or can actually cause or worsen the mood disorder.

MARIJUANA USE AND ITS IMPACT ON TEENAGERS AND DEPRESSION OR SUICIDE

Marijuana is the most commonly abused drug among teenagers, so it is important to look at the possible negative effects on this age group. A 2019 study examined the association between cannabis use in adolescence and the risk of developing depression and other mood disorders in young adulthood. The study found that cannabis use in adolescence leads to a 37% increased chance of depression diagnosis as a young adult, a 50% increase in suicidal thoughts, and a concerning 346% or 3.5-fold increase in suicide attempts (Gobbi et al., 2019).

MARIJUANA CAN WORSEN THE NEUROCHEMISTRY OF DEPRESSION

Studies have shown that marijuana use is associated with some significant negative effects on depression, but why? The answer may be found by looking at how marijuana impacts the level of serotonin, one of the brain’s most important mood-boosting chemical messengers.

Low levels of serotonin in the frontal cortex of the brain, a brain region that plays a role in emotion, has been strongly associated with the development of depression. A common treatment for depression is a type of drug called a selective serotonin reuptake inhibitor, or SSRI. These drugs are thought to raise serotonin levels by inhibiting the reuptake process that brain cells use to remove excess serotonin. But several lines of evidence suggest that marijuana has negative effects on serotonin levels and may block the action of serotonin-boosting drugs.

Animal studies have shown that cannabinoids can have an anti-serotonin effect after both short- and long-term use. One interesting study measured serotonin levels in the brain after dosage with citalopram, a common SSRI, and WIN55,212-2, a compound that activates the same cannabinoid receptors as THC (and therefore potentially has similar effects on the brain as marijuana use). The study measured serotonin levels after dosing with citalopram alone, citalopram with WIN55,212-2, or WIN55,212-2 alone (Kleijn et al., 2011).

The results showed that citalopram’s effectiveness at increasing levels of serotonin in the brain was essentially negated by WIN55,212-2. This means that activating cannabinoid receptors in the frontal cortex has the potential to block the therapeutic effect of the most commonly used antidepressants.

Figure source: Kleijn, J., Cremers, T.I.F.H., Hofland, C.M., and Westerink, B.H.C. (2011). CB-1 receptors modulate the effect of the selective serotonin reuptake inhibitor, citalopram on extracellular serotonin levels in the rat prefrontal cortex. Neurosci. Res., 70, 334–337.

Other animal studies show that the THC in marijuana can decrease the brain’s ability to produce and release serotonin in the frontal cortex (Bambico et al., 2010, Moranta et al., 2004, Sagredo et al., 2006, Welch et al., 1971). These anti-serotonin effects may explain the increased rates of depression in marijuana users, why many marijuana users report depression as a side effect of use, and why many marijuana users have a poorer response to treatments than non-users.

MANAGING CHRONIC DEPRESSION

As a clinical psychiatrist, I believe that anyone with depression deserves full recovery and that full recovery is a realistic, attainable goal.

Whether your current treatment plan involves marijuana use or not, I encourage anyone struggling with depression to start tracking their symptoms daily or weekly in a journal or spreadsheet. Score your symptoms based on how good or bad they are on a given day, and track if your symptoms get better or worse over time on your current treatment plan. Treatments for depression are intended to relieve and ultimately eliminate depression symptoms, so if your symptoms have not improved after a while, consider making modifications to your treatment plan with your doctor.

For those whose treatment plan currently includes marijuana use, it may seem contradictory at first that reducing or stopping marijuana use could help. However, a recent study has shown that decreasing marijuana use can decrease the severity of depression and anxiety symptoms and improve sleep quality (Hser et al., 2017), so it may be worth exploring.