Depression is characterized by a persistent feeling of sadness and loss of interest or pleasure in normally enjoyable activities. Depression is just one of many mood disorders that affect the general population, yet commonly goes unnoticed. People who suffer from depression are believed to have shorter life expectancies than those who don’t.

Depression is thought to be caused by low levels of brain chemicals (neurotransmitters), such as serotonin and dopamine. Typical treatments for this disorder include antidepressant medications that act to increase levels of neurotransmitters as well as professional counseling. While antidepressants can be effective for patients who suffer from severe forms of depression, they seem to have little to no effect on patients with mild or moderate depression. Further, many people become resistant to their effects over time.

Cannabis and Depression

Cannabis has been used to treat depression throughout history. In 1621, English clergyman Robert Burton recommended its use in his book The Anatomy of Melancholy, and doctors in India during the same period were actively using it to treat their patients’ depression.

A growing body of research suggests that marijuana may be beneficial in the treatment of depression. This has been confirmed by patients themselves, as a survey conducted in 2005 found that 22% of medical marijuana patients in the UK indicated using marijuana for depression.

Besides these self-reports of patients, research also points to the endocannabinoid system as having a therapeutic role in depression. For example, studies conducted on rodents have linked suppression of endocannabinoid activity to symptoms of major depression, while other studies have found increased endocannabinoid activity to have antidepressant-like effects.

The Research Institute on Addictions (RIA) is a research center at the University of Buffalo and a national leader in the study of alcohol and substance abuse issues. RIA’s research programs are supported by federal, state and private foundation grants. Senior research scientist, Samir Haj-Dahmane, states “Chronic stress is one of the major causes of depression. Using compounds derived from cannabis – marijuana – to restore normal endocannabinoid function could potentially help stabilize moods and ease depression.”

"People absolutely do treat their depression with cannabis," says Felicia Carbajal of My Health Freedom, a medical marijuana advocacy group out of California. "New, non-cannabinoid cannabis-based terpene blends are the newest rage for symptoms of depression." "Mangos have myrcene in them, which has been shown to help with symptoms of depression," says Carbajal. "Lemons have limonene, which is also anti-depressive, but also anxiolytic. There are cannabis strains which have both, in addition to small amounts of linalool (lavender), which also has stress-relieving effects. So this natural ratio, which is unique to cannabis, can have unique anti-depressive effects when simply used as an aromatherapy inhaler."

It’s also important to note that most of the scientific evidence concerning marijuana and depression comes from preclinical studies, meaning that human testing has been very limited. While medical marijuana has not been tested in human subjects directly for the treatment of clinical depression, evidence from studies conducted on cancer and Multiple Sclerosis (MS) patients certainly seems to support the use of medical marijuana and other marijuana-based treatments for symptoms of depression.

Cannabis, a faster-working alternative to antidepressants, stimulates the endocannabinoid system, and has also been shown to increase neurogenesis – the growth of new brain cells – much like traditional anti-depressant medications. Stress and depression are known to decrease neurogenesis, which can also be a side-effect of using alcohol, nicotine, opiates and cocaine. This natural remedy offers patients peace of mind and battles stress by enhancing mood, providing energy and focus, relieving anxiety, inducing hunger, and combating insomnia.

While researchers can’t completely confirm if marijuana is effective for treating depression, Zachary Walsh, an assistant professor of psychology at the University of British Columbia who heads a research lab focused on marijuana and mental health points out that other medicines have the same problem. He says that in some cases, typical antidepressants are no more effective than a placebo and have side effects that may be more severe than those of marijuana.

Can Marijuana Cause Depression/Mental Illness?

A link between marijuana use and depression is often suggested., Experts believe that depression is not directly caused by marijuana use, but rather happens to share a common set of underlying genetic and environmental factors.

But despite confirming that activation of the endocannabinoid system can improve symptoms of depression, studies have shown that Tetrahydrocannabinol (THC) in Cannabis can have both depressant and antidepressant-like effects, depending on the dosage.

A study published in 2007 found that low doses of a synthetic (“single molecule”) form of THC (refers to “Big Pharma’s” attempt to produce a “marketable” drug) raised serotonin levels and produced strong antidepressant-like effects in rats, whereas high doses reversed the effects and worsened depression. Focusing on a “single molecule” can have dubious effects on the body compared to whole plant cannabis.

Does cannabis cause depression and schizophrenia or do people with these disorders use it as a medication?

An important factor in the answer could be the age of the person consuming cannabis.

According to research conducted by Dr. Gobbi in 2009, daily use of marijuana can cause depression and anxiety in teens. “Cannabis, when consumed by adolescents, induces depression and anxiety later in adulthood, even if the people did not have any susceptibility for these mental diseases,” she says.

Cannabis Use by Adolescents

Over the past few years, research has strongly suggested that there is a clear link between early cannabis use and later mental health problems in those with a genetic vulnerability - and that there is a particular issue with the use of cannabis by adolescents.

A study following 1600 Australian school-children, aged 14 to 15 for seven years, found that while children who use cannabis regularly have a significantly higher risk of depression, the opposite was not the case - children who already suffered from depression were not more likely than anyone else to use cannabis. However, adolescents who used cannabis daily were five times more likely to develop depression and anxiety in later life.

Psychoses - schizophrenia and bipolar disorder: There is now sufficient evidence to show that those who use cannabis particularly at a younger age, such as around the age of 15, have a higher than average risk of developing a psychotic illness, such as schizophrenia or bipolar disorder. These studies also show that the risk is dose-related. In other words, the more cannabis someone used, the more likely they were to develop a psychotic illness. Furthermore, a study in Australia recently showed that those who used cannabis could develop the illness about 2.70 years earlier than those who did not.

Why should teenagers be particularly vulnerable to the use of cannabis? It is thought that this has something to do with brain development. The brain is still developing in the teenage years – up to the age of around 20. A massive process of ‘neural pruning’ is going on. This is rather like streamlining a tangled jumble of circuits so they can work more effectively. Any experience, or substance, that affects this process has the potential to produce long-term psychological effects.

It is also known that not everyone who uses cannabis, even at a young age, develops a psychotic illness. The available research shows that those who have a family history of a psychotic illness, or those who have certain characteristics such as schizotypal personality, or possibly have certain types of genes, may increase the risk of developing a psychotic illness following the regular use of strong cannabis.


Marijuana is sometimes referred to as ‘green Prozac’ due to the fact that many users find it helpful in lifting their spirits. But can it actually be an effective treatment for depression? “A lot of people report using cannabis effectively to treat depression,” says Zachary Walsh, an assistant professor of psychology at the University of British Columbia who heads a research lab focused on marijuana and mental health.

“For some, medical marijuana is helpful, not curative. But others have been able to completely eliminate their dependence on other medications altogether.” – Jeremy Spiegel, MD (2013)

“Those who consume marijuana occasionally or even daily have lower levels of depressive symptoms than those who have never tried marijuana… The potential for medical conditions to contribute to spurious links between marijuana and greater depression requires further investigation.” – Thomas F. Denson, PhD (2006)

“Not only does marijuana not cause depression, it looks like it may actually alleviate it… Those who use marijuana to battle the symptoms of illness may be depressed because of their illness, not because of marijuana.” – Mitch Earleywine, PhD (2005)

“Patients who use cannabis to ‘relax’ may be treating the anxiousness sometimes associated with depression. Cannabis aids the insomnia sometimes present in depression and can improve appetite. Better pain control with cannabis can reduce chronic pain related depression. While cannabis cannot yet be considered a primary treatment of major depression it may improve mood when used under physicians supervision and in combination with therapy and/or SSRI’s.” – Jay Cavanaugh, PhD (2003)

“The power of cannabis to fight depression is perhaps its most important property.” – Tod Mikuriya, MD (1997)

Research on Marijuana and Depression

A 2007 study found that low doses of THC can increase serotonin levels in mice. Although there is no clinical consensus on whether or not low serotonin levels cause depression, the majority of pharmacological treatments for depression (SSRIs, or selective serotonin reuptake inhibitors) focus on increasing existing “available” serotonin.

For depression that is caused by chronic stress, components of marijuana may be an effective treatment, according to a 2015 study by Scientists at the University at Buffalo’s Research Institute on Addictions (RIA). The findings showed that stress caused a decrease in cannabis-like molecules naturally found in the brain, leading to behavior that mimicked depression. “In the animal models we studied, we saw that chronic stress reduced the production of endocannabinoids, leading to depression-like behavior,” says RIA senior research scientist Samir Haj-Dahmane, PhD.

Another study published in 2007 by a team at McGill University showed that administering low doses of THC could work like an antidepressant by increasing serotonin. However, in high dosages, THC decreased serotonin and seemed to worsen depression. “These findings confirm what has been reported by people who smoke cannabis,” explains Dr. Gabriella Gobbi, who co-authored the McGill study. “Often it produces euphoria, calmness, sociability, but in other circumstances it can produce bad dreams and negative feelings.”

“Marijuana does help with my depression. It makes it manageable and evens out the rough edges, so to speak. While I might occasionally get depressed, it is appropriate for the situation and temporary. It does not control my life, and I don’t sink into that hopeless black hole of depression that leaves one completely dysfunctional.” – Cheri Sicard, founder of The Marijuana Lifer Project, was diagnosed with depression in her 30s 


The evaluation of medical marijuana for depression is still in its early stages. Currently, researchers share the opinion that possible benefits include the restoration of “normal” endocannabinoid function and mood stabilization. 

Overall there hasn’t been enough research in the field, and the type of research needed, to confirm whether marijuana can effectively treat quite complex. Not only do we have to determine the dose-effect of cannabis on depressive people, but also which plant strain, kind of cannabinoid(s) and ratio of those cannabinoids may have a positive effect on mood.