Does Cannabis Use Increase or Decrease the Risk of Depression?

For those individuals who chronically use marijuana, either medically or for recreational purposes, there may be an increased risk of developing depression with frequent use. Or heavy cannabis use may actually help relieve depression. It all depends on who you ask since we have information supporting both. The definitive answer is still pending as more research becomes available.


A while back a study was published in the American Journal of Psychiatry that suggested for adults who chronically abuse marijuana (marijuana abuse syndrome), they may be at increased risk for depression.

As reported in Scientific American:

Gregory B. Bovasso of the University of Pennsylvania Treatment Research Center studied a random sample of 1,920 adults who were interviewed first in 1980 and again between 1994 and 1996. Subjects diagnosed with cannabis abuse at the start of the study were four times more likely to experience depressive symptoms, particularly suicidal thoughts and the inability to experience pleasure, than their non-smoking counterparts. Participants who were depressed at the outset of the study, however, were no more likely to abuse marijuana later on, the study found.

Trying to ferret out which symptom or disorder came first makes this a daunting problem. On the one hand we have a subset of patients who were diagnosed early on with cannabis abuse syndrome, basically what medicine calls ‘marijuana addiction’. It was this patient population that was at increased risk (400%) for depression. Those diagnosed early on with depression were not more likely to become addicted to pot or to have an increased use of it. Often times it’s hard to tell what caused what.

Did those diagnosed with cannabis abuse syndrome use marijuana to ease their symptoms of depression because they were already depressed, or did the chronic use of cannabis cause these patients to become depressed? Or is something else at play? Such as what other habits do these patients have, other than pot smoking, which may predispose them to depression unrelated to pot use?

The National Health Service (NHS) of the United Kingdom stated in a July 15, 2011 article titled “Does Cannabis Interact with Antidepressants or Lithium?” and posted on its website:

It is not clear how often cannabis itself can cause depression, but research suggests that this can happen. It is therefore recommended that if you are depressed, and you use cannabis regularly, you should try giving up and see if that helps.

Dr. Simon, Senior Scientific Investigator in the Center for Health Studies at the Group Health Cooperative, stated the following in a Jan. 2012 column titled “Ask the Doctor Q & A,” published on the Depression and Bipolar Support Alliance website:

Using marijuana can certainly contribute to or worsen depression. Low motivation, fatigue, and withdrawal from positive activities are central features of depression and marijuana can worsen each of those problems. Some people do say that marijuana dulls anxiety or negative feelings. But it also dulls energy and motivation. And we know that activation and engagement are key parts of recovery from depression.

The University of Washington Alcohol and Drug Abuse Institute stated the following in an online fact sheet titled “Mental Health and Marijuana,” based on information from the National Cannabis Prevention and Information Centre (accessed June 14, 2012):

Marijuana may seem to help ease depression before the effects of the drug wear off; however, after that, smoking marijuana may make depression worse.Those who use marijuana have been shown to have higher levels of depression and depressive symptoms than those who do not use marijuana. Although results are mixed, there is a substantial amount of evidence to suggest that marijuana use, particularly frequent or heavy use, predicts depression later in life. Young women appear to be more likely to experience this effect.

The Office of National Drug Control Policy (ONDCP) stated the following in its May 2008 report titled “Teen Marijuana Use Worsens Depression: An Analysis of Recent Data Shows ‘Self-Medicating’ Could Actually Make Things Worse,” available on the National Criminal Justice Reference Service website:

Some teens use marijuana to relieve the symptoms of depression (‘self-medicate’), wrongly believing it may alleviate these depressed feelings…

However, recent studies show that marijuana and depression are a dangerous combination. In fact, using marijuana can worsen depression and lead to more serious mental health disorders, such as schizophrenia [only in those at risk, such as a family history of psychosis], anxiety, and even suicide. Weekly or more frequent use of marijuana doubles a teen’s risk of depression and anxiety.


Dr. Daniel Hall-Flavin throws some light on this complicated issue in an article for the Mayo Clinic website:

Some research suggests that marijuana smokers are diagnosed with depression more often than nonsmokers are — particularly regular or heavy marijuana users. However, it doesn’t appear that marijuana directly causes depression.

It’s likely that the genetic, environmental or other factors that trigger depression also lead to marijuana use. Some people with depression may use marijuana as a way to detach from their depressive symptoms. Heavy users may appear depressed as a result of the dulling effects of the drug on feelings and emotions.

The bottom line: Marijuana use and depression accompany each other more often than you might expect by chance, but there’s no clear evidence that marijuana directly causes depression.

Some may take umbrage with the statement regarding the ‘dulling effect on feelings and emotions’. Many marijuana users often report an intensification of feelings and emotions — an effect sought after for creative applications. The effects of cannabis are not usually described as ‘Valium-like’, or soporific, where there is a true dulling of emotions; or the use of cannabis causing a similar muffling of higher cortical functioning seen with opiate use, barbiturate use or alcohol abuse.

In the United Kingdom:

Researchers at the University of Bristol in the United Kingdom reviewed almost 80 previous studies that involved a total of about 6,500 people. The investigators concluded that medical marijuana may offer some relief for people with cancer-related pain, nerve pain or muscle spasms caused by multiple sclerosis.

The analysis did not find evidence to support the use of medical marijuana in people with depression, psychosis, anxiety disorders, sleep problems, Tourette syndrome or glaucoma.

This is a hot topic because the use of pot has been increasing at an alarming rate. From an article appearing in JAMA Psychiatry:

Marijuana use in the United States more than doubled between 2001 and 2013, according to research reported this year in the journal JAMA Psychiatry. Over this 12-year period, the estimated number of U.S. adults who had used marijuana in the previous 12 months grew from 4.1 percent in 2001 to 9.5 percent in 2013. Marijuana-use disorders, which include problems with drug addiction and dependence, also rose, increasing from 1.5 percent of the adult population in 2001 to 2.9 percent in 2013, the study showed.

While marijuana use in the UK has remained stable since 2009/10.

The Home Office reports that, as in previous years, cannabis was the most commonly used drug in the last year, with 6.7 per cent of adults aged 16 to 59 using it in the last year, similar to the 2013/14 survey (6.6%; Figure 1.2). Over the longer-term, between the 1998 and 2003/04 surveys, the last year use of cannabis was stable, at around 10 per cent of adults, before falling to 6.5 per cent in 2009/10. The trend since the 2009/10 survey has been relatively flat, at between six and seven per cent (Table 1.2).

this pic

Furthermore, marijuana is becoming more and more potent. From the NIDA Research Report series website:

Marijuana potency, as detected in confiscated samples, has steadily increased over the past few decades. In the early 1990s, the average THC content in confiscated cannabis samples was roughly 3.7 percent for marijuana and 7.5 percent for sinsemilla (a higher potency marijuana from specially tended female plants). In 2013, it was 9.6 percent for marijuana and 16 percent for sinsemilla.

What we don’t know is how marijuana affects kids who are routinely exposed to much higher potency weed than the generations before them. Those who grew up in the 60s through the 90s experienced pot that was one third the potency of the newer varietals kids are exposed to today. Some modern strains are clocking in at nearly 30% THC, that’s 300 mg THC per gram of cannabis, while the newer types of concentrates may be nearly three times this potency!

Experts are concerned about the increases in potency and adolescents using the drug because the youngsters brain is much more vulnerable to the varied effects of cannabis especially on the psycho-social aspects of cerebral function.

Science confirms that the adolescent brain, particularly the part of the brain that regulates the planning complex cognitive behavior, personality expression, decision-making and social behavior, is not fully developed until the early to mid-20s. Developing brains are especially susceptible to all of the negative effects of marijuana and other drug use.

That’s why further studies are needed. Authorities have mixed opinions on the role pot plays in psychiatric diseases such as psychosis, depression and anxiety. When we look at more recent studies we see that there are some publications indicating that marijuana may actually reduce the risk of depression.

The Huffington Post published an article that found pot use may be an effective treatment for stress-induced depression (in a rat model):

Neuroscientists from the University of Buffalo’s Research Institute on Addictions found that endocannabinoids… — may be helpful in treating depression that results from chronic stress.

In studies on rats, the researchers found that chronic stress reduced the production of endocannabinoids, which affect our cognition, emotion and behavior, and have been linked [when stimulated] to reduced feelings of pain and anxiety, increases in appetite and overall feelings of well-being. The body naturally produces these compounds, which are similar to the chemicals in cannabis. Reduction of endocannabinoid production may be one reason that chronic stress is a major risk factor in the development of depression.

Using compounds derived from cannabis — marijuana — to restore normal endocannabinoid function could potentially help stabilize moods and ease depression,” lead researcher Dr. Samir Haj-Dahmane said in a university press release.

Recent research around marijuana’s effect on symptoms of post-traumatic stress disorder further bolsters the Buffalo neuroscientists’ findings, since both disorders involve the way the brain responds to stress. A study published last year in the journal Neuropsychopharmacology, for instance, found synthetic cannabinoids triggered changes in brain centers associated with traumatic memories in rats, preventing some of the behavioral and physiological symptoms of PTSD. Another study published last year found that patients who smoked cannabis experienced a 75 percent reduction in PTSD symptoms.

In 2012 a paper entitled “High on Life? Medical Marijuana Laws and Suicide,” was published by the The Institute for the Study of Labor (IZA) in its Discussion Paper Series. They feel that pot has produced a significant positive effect on the rate of suicide and depressive disorders:

Consistent with the hypothesis that marijuana can be an effective treatment for depression and other mood disorders, there appears to be a sharp decrease in the suicide rate of 15- through 19-year olds males in the treatment states as compared to the control states approximately two years after legalization…

Our results suggest that the legalization of medical marijuana is associated with a 5 percent decrease in the total suicide rate, an 11 percent decrease in the suicide rate of 20- through 29-year-old males, and a 9 percent decrease in the suicide rate of 30- through 39 year-old-males….

The strong association between alcohol consumption and suicide related outcomes found by previous researchers… raises the possibility that medical marijuana laws reduce the risk of suicide by decreasing alcohol consumption.

The possibility that pot can reduce alcohol consumption, especially in those with dependency issues, might be one of its best ‘side effects’. A similar claim has been made with pot’s ability to decrease opiate dependence and reduce overdose risk. This effect appears to be true in states or countries that have legalized medical and/or recreational cannabis.

Dr. Christopher Rasmussen
Dr. Christopher Rasmussen MD,MS, an anesthesiologist with a Master’s degree in traditional Chinese medicine, is a professor, lecturer, seminar provider, and world authority on preventive medicine.For more information on preventive medicine see



  1. As a fifty year medical user I find just about all of these conflicting studies accurate. Time, place, and state of mind affect many mood altering drugs, THC falls in this class. The Extract I have used for the last 12 years comes in at 60% THC and with a gram lasting 5 days that is a 120 mg per day dose rate. This is more than can be casually smoked.
    I am autistic and marijuana is the only medication used. I have spent a total of four years institutionalized, half of the time while a minor. Since becoming adult I have been institutionalized only when marijuana was unavailable for longer than 90 days.
    I became a gardener and never run out. I supply to several veterans at cost in my military hometown. Marijuana does not help PTSD in everyone, but for some it makes all the difference.

Have Your Say


Related News