Medical marijuana is an effective treatment for depression: True or False?

As any point of discussion, related to the medical marijuana use, the possibility to use cannabis for the clinical depression draws a lot of controversy both in the medical scientific world and among general population common views. As expected, different researchers come to the opposite conclusions on the subject. While I, personally, find the marijuana positive impact conclusions more scientifically supported by obtained results, I will provide both points of view to your consideration.

Probably, the most logical conclusion has been made as result of the recent Canadian Study, which somehow balances the negative and positive view in regards to Marijuana use for clinical depression treatment.

THC, the active ingredient in marijuana, increases serotonin when smoked in low doses, similar to SSRI antidepressants, such as Prozac, according to researchers from McGill University and Le Centre de Recherche Fernand Seguin of Hospital in Quebec and l’Universitй de Montrйal in Montreal.
But at higher doses, the effect reverses itself and can actually worsen depression and other psychiatric conditions like psychosis.

During the study, published in the October 24, 2007 issue of The Journal of Neuroscience, laboratory rats were injected with the synthetic cannabinoid WIN55, 212-2 and then tested with the Forced Swim test - a test to measure “depression” in animals.

The researchers observed an antidepressant effect of cannabinoids and an increased activity in the neurons that produce serotonin. However, increasing the cannabinoid dose beyond a set point completely undid the benefits, said Dr. Gabriella Gobbi of McGill University and Le Centre de Recherche Fernand Seguin of Hфpital Louis-H. Lafontaine.

"So we actually demonstrated a double effect: At low doses it increases serotonin, but at higher doses the effect is devastating, completely reversed," she said in a news release.

The antidepressant and intoxicating effects of cannabis are due to its chemical similarity to natural substances in the brain known as "endo-cannabinoids," which are released under conditions of high stress or pain, said Gobbi. They interact with the brain through structures called cannabinoid CB1 receptors. The study demonstrated that these receptors have a direct effect on the cells producing serotonin, which is a neurotransmitter that regulates the mood, she said.

Let’s review other specialists’ points on the topic, but let’s make our own mind, how solid provided arguments are.

PRO - Cannabis use for Depression Treatment

1. Frank Lucido, MD, a private practice physician, stated in his article "Implementation of the Compassionate Use Act in a Family Medical Practice: Seven Years Clinical Experience," available on his website:

With appropriate use of medical cannabis, many of these patients have been able to reduce or eliminate the use of opiates and other pain pills, ritalin, tranquilizers, sleeping pills, anti-depressants and other psychiatric medicines...

2. George McMahon, an author and medical marijuana patient of the U.S. Federal Drug Administration’s Investigational New Drug (IND) Program, stated in his 2003 book Prescription Pot:

People who have never struggled with a life threatening or disabling illness often do not comprehend how debilitating the resulting depression can be. Long days spent struggling with sickness can wear patients down, suppress their appetites and slowly destroy their wills to live. This psychological damage can result in physiological effects that may be the difference between living and dying.
The elevated mood associated with cannabis definitely affected my health in a positive manner. I was more engaged with life. I took walks and rode my bike, things I never considered doing before in my depressed state, even if I had been physically capable. I ate regular meals and I slept better at night. All of these individual factors contributed to a better overall sense of well-being.

3. Tod Mikuriya, MD, a psychiatrist and medical coordinator, co-wrote in the 1997 book Marijuana Medical Handbook:

The power of cannabis to fight depression is perhaps its most important property.

4. The Journal of Clinical Investigation stated in an Oct. 13, 2005 article "Cannabinoids Promote Embryonic and Adult Hippocampus Neurogenesis and Produce Anxiolytic- and Antidepressant-like Effects" by Xia Zhang et al.:

We show that 1 month after chronic HU210 [high-potency cannabinoid] treatment, rats display increased newborn neurons [brain cell growth] in the hippocampal dentate gyrus [a portion of the brain] and significantly reduced measures of anxiety- and depression-like behavior. Thus, cannabinoids appear to be the only illicit drug whose capacity to produce increased hippocampal newborn neurons is positively correlated with its anxiolytic- and antidepressant-like effects.

5. The Journal of Acquired Immune Deficiency Syndrome, stated in a Jan. 2004 article on a study designed by Prentiss, Power, Balmas, Tzuang and Israelski "to examine the prevalence and patterns of smoked marijuana and perceived benefit" among 252 HIV patients:

Overall prevalence of smoked marijuana in the previous month was 23%. Reported benefits included relief of anxiety and/or depression (57%), improved appetite (53%), increased pleasure (33%), and relief of pain (28%).

6. Jay Cavanaugh, PhD, National Director for the American Alliance for Medical Cannabis, wrote in his 2003 article "Cannabis and Depression," published on the American Alliance For Medical Cannabis website:

Numerous patients report significant improvement and stabilization with their bipolar disorder when they utilize adjunctive therapy with medical cannabis. While some mental health professionals worry about the impact of cannabis on aggravating manic states, most bipolar patients trying cannabis find they ’cycle’ less often and find significant improvement in overall mood. Bipolar disorders vary tremendously in the time spent in the depressive versus manic states. Those who experience extended depressive episodes are more likely to be helped with cannabis.


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.

7. Bill Zimmerman, PhD, former President of the Americans For Medical Rights, stated in his 1998 book Is Marijuana the Right Medicine For You?:

Some patients have found the mood altering effects of marijuana to be helpful for treating mood disorders such as anxiety, depression and bipolar (manic-depressive) illness. Using marijuana to treat mood disorders was described in medical writings in the 19th and early 20th centuries...
However, using marijuana to treat mood disorders can be very tricky... If you intend to use marijuana for this purpose, it is very important that you thoroughly discuss it with your doctor. Patients who respond well report that marijuana not only diminishes their undesirable moods, it also motivates them to productivity. For some of these patients, depression was a by-product of a debilitating disease or illness for which marijuana provided a welcome remedy. For others, the marijuana seems to have acted directly on the depression.


The mental component of the pre-menstrual syndrome (PMS) often causes psychological problems and is now technically classified as an atypical (not typical) depression. Many women report benefit from using marijuana to improve the symptoms of PMS.

CON - Cannabis use for Depression Treatment

1. Health Services at Columbia University (HSC), in the GoAskAlice section of their website, stated in a Feb. 4, 2005 response to a question from "a concerned boyfriend" who asked "She says smoking pot is like self-medicating - it is better than using anti-depressants. She also claims smoking pot helps with depression because of how it helps produce Seratonin in the body.... Does smoking pot really help with managing your anxiety, depression, etc.?":

Marijuana DOES NOT produce serotonin. However, it does affect a substance in the brain called anandamide. Anandamide causes a soothing sensation in the body when it reacts with THC (tetrahydrocannabinol), the active substance in marijuana. It is the anandamide that causes your girlfriend to relax when using marijuana in low to medium doses....


While marijuana use may seem like a soother to your girlfriend, she may need to know about the negative effects... Marijuana appears to increase the risk of developing depression and/or schizophrenia the more that one uses it....

[Y]our girlfriend believes that she is self-medicating, when she may be contributing to her depression. Her depression could manifest itself in the future, since marijuana users typically withdraw from social situations, adding to depression.

Also consider what it is about antidepressants that are so abhorrent to your girlfriend. Why would marijuana, an illegal substance, be preferable to a controlled medication taken under medical advisement to manage her stress and depression?...

[S]he may agree to see her medical or primary care provider for a medical exam and evaluation. If she then has a diagnosis of depression and/or anxiety, or is referred to someone who specializes in working with people with these conditions, then chances are she will feel better than when she ’prescribes’ marijuana for herself.

2. Karen Cameron, RNC, MSN, Correspondent for WebMD, stated in a June 14, 2004 WebMD article "Are Depression and Marijuana Linked?":

It is pretty well known that the psychoactive chemicals in marijuana interfere with the balancing process that antidepressants work toward.

As you may already know, depression is a biochemical illness -- an imbalance in chemicals in the brain. Those antidepressants help things become better balanced, but they can’t do the job nearly as well if one is smoking marijuana.

Marijuana contributes to depression and destroys natural sleep. There really is no good reason to continue smoking it.

3. The UK’s National Health Service (NHS) stated in its Feb. 9, 2006 website article "Does Cannabis Interact With Antidepressants Or Lithium?":

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. One small study suggests that a chemical in cannabis might cause severe anxiety and unease in people with moderate to severe depression.

Tachycardia (an abnormally fast heart-beat), dizziness, anxiety, drowsiness, nausea, vomiting, difficulty sleeping and confusion are all possible side effects of cannabis. These side effects can also be caused by certain antidepressants, so using cannabis at the same time can make them worse.
Laboratory work suggests that cannabis might affect the way these [anti-depressant] medicines work. It is not clear what affect this may have on people, so MAOIs and cannabis should not be taken together.

There is no published research that has looked at taking these medicines and cannabis. However, they are too new to be sure and a problem might have been missed. Therefore the newer antidepressants should not be taken with cannabis due to lack of information.

4. Nancy Schimelpfening, the About Guide to Depression for About.com, stated in her About.com article "Is It A Bad Idea to Use Marijuana to Relieve Depression":

Although there is preliminary evidence that marijuana may have antidepressant properties, many argue there are also some important drawbacks to it’s usage. There is a well-known phenomenon called ’amotivational syndrome’ in which chronic cannabis users become apathetic, socially withdrawn, and perform at a level of everyday functioning well below their capacity prior to their marijuana use.

Although the depressed person may feel relief from their symptoms, this may be an illusion of well-being if the person loses motivation and productivity. Furthermore, if the drug is smoked, it can be far more harmful to the respiratory system that tobacco use because of the fact that it is not filtered.

I would also like to mention a USC College study finding no link between symptoms of depression and regular marijuana use, denying popular accusation of Marijuana as being one of the suspects for the depression development. The study results confirmed that Marijuana smokers are less depressed than those who never smoke. Interesting is that study results were not expected even by the researchers.

College doctoral candidate Tom Denson co-authored the study on marijuana and depression to be published in the journal, Addictive Behaviors. Denson wrote the report with psychologist Mitch Earleywine, a former College associate professor and author of Understanding Marijuana (Oxford University Press, 2002).

While the study found that those who smoke marijuana for medical reasons were more depressed than other smokers, they were less depressed overall than nonsmokers.

Rather, daily or weekly marijuana users - including those smoking the drug for medical rather than recreational reasons - had fewer symptoms of depression than nonusers. Further, marijuana users were more likely to report positive moods and fewer somatic complaints such as sleeplessness, poor appetite and trouble completing their daily routine, the study stated.

The Internet study questioned more than 4,400 marijuana users and non-users. The researchers said the online study made it possible to include the severely depressed or those who would not participate in an in-person or telephone survey about an illicit drug.

After a story about the study appeared in the Nov. 18, 2005 Albany Times Union, Denson received correspondence from researchers who said their similar-smaller scale studies resulted in the same findings.

Sources and Additional Information:
http://medicalmarijuana.procon.org/viewanswers.asp?questionID=000226
http://www.foxnews.com/story/0,2933,304996,00.html
http://health.usnews.com/articles/health/brain-and-behavior/2008/05/09/teen-depression-worsened-by-marijuana-government-says.html
http://www.doctordeluca.com/Library/WOD/WPS3-MedMj/DecreasedDepressionInMjUsers05.pdf