Last updated on: 5/28/2009 3:45:00 PM PST
Does Marijuana Cause Depression or Other Mood Disorders?


General Reference (not clearly pro or con)
The Institute of Medicine published in its Mar. 1999 report titled “Marijuana and Medicine: Assessing the Science Base”:

"The psychological effects of cannabinoids, such as anxiety reduction, sedation, and euphoria, can influence their potential therapeutic value.

Those effects are potentially undesirable in some patients and situations and beneficial in others. In addition, psychological effects can complicate the interpretation of other aspects of the drug's effect."

Mar. 1999 - Institute of Medicine 
"Marijuana and Medicine: Assessing the Science Base" (988 KB)  



PRO (yes)

Gregory B. Bovasso, PhD, Assistant Professor of Behavioral Sciences at the Community College of Philadelphia, wrote the following in his Dec. 2001 article titled "Cannabis Abuse as a Risk Factor for Depressive Symptoms," published in the American Journal of Psychiatry:

"In participants with no baseline depressive symptoms, those with a diagnosis of cannabis abuse at baseline were four times more likely than those with no cannabis abuse diagnosis to have depressive symptoms at the follow-up assessment, after adjusting for age, gender, antisocial symptoms, and other baseline covariates.

In particular, these participants were more likely to have experienced suicidal ideation and anhedonia during the follow-up period.

Among the participants who had no diagnosis of cannabis abuse at baseline, depressive symptoms at baseline failed to significantly predict cannabis abuse at the follow-up assessment."

Dec. 2001 - Gregory Bovasso, PhD 



The British Medical Journal reported in a Nov. 23, 2002 article by George Patton, MD, et al., "Cannabis Use and Mental Health in Young People: Cohort Study":

"Daily [cannabis] use in young women was associated with an over fivefold increase in the odds of reporting a state of depression and anxiety after adjustment...

Weekly or more frequent cannabis use in teenagers predicted an approximately twofold increase in risk for later depression and anxiety...

The prevalence of depression and anxiety increased with higher extents of cannabis use, but this pattern was clearest in female participants."

Nov. 23, 2002 - British Medical Journal 



Thomas Edward Radecki, MD, JD, Research Director of Doctors & Lawyers for a Drug Free Youth, stated on his website (accessed Mar. 9, 2006):

"Depression is a common side-effect of smoking marijuana. The evidence of a cause-effect relationship is very solid....

I have seen dozens and dozens of patients who have become seriously mentally ill thanks to the brain damage caused by marijuana. It is a major cause of depression and schizophrenia in our society as well as a factor in preventing our psychiatric treatments from working effectively.

It changes the personality, damages the memory, seriously impairs school performance, and causes auto crashes and death for far too many individuals."

Mar. 9, 2006 - Thomas Edward Radecki, MD, JD 



The Office of National Drug Control Policy (ONDCP) noted in its May 3, 2005 website article "Marijuana and Mental Health":

"There is an increased risk of depression, suicidal thoughts and schizophrenia as a result of marijuana use, even among people with no prior history of a disorder....

Recent evidence suggests that some people's genetic make-up may predispose them to be particularly vulnerable to the effects of marijuana on mental health."

May 3, 2005 - Office of National Drug Control Policy (ONDCP) 



CON (no)

Mitch Earleywine, PhD, Associate Professor of Psychology at the State University of New York at Albany, noted in a Nov. 17, 2005 press release:

"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. Studies that do not identify medical use might falsely implicate marijuana, rather than sickness, as the cause of depressed feelings...

Thirty percent to 40% of patients with bipolar disorder are not consistently helped by or cannot tolerate standard medications. In the course of the authors' studies of the medical uses of cannabis (Grinspoon & Bakalar 1997), a number of sufferers were discovered who believed marihuana to be more effective than conventional anti-manic drugs, or who used it to relieve the side effects of lithium."

Nov. 17, 2005 - Mitch Earleywine, PhD 



Lester Grinspoon, MD, Professor of Psychiatry at the Harvard Medical School, stated in an Apr. 1998 Journal of Psychoactive Drugs article:

"Thirty percent to 40% of patients with bipolar disorder are not consistently helped by or cannot tolerate standard medications. In the course of the authors' studies of the medical uses of cannabis (Grinspoon & Bakalar 1997), a number of sufferers were discovered who believed marihuana to be more effective than conventional anti-manic drugs, or who used it to relieve the side effects of lithium."

Apr. 1998 - Lester Grinspoon, MD 



Ethan Russo, MD, Senior Medical Advisor at the Cannabinoid Research Institute, wrote the following in the Dec. 2002 issue of Cannabis Health:

"A surprising number of people so afflicted [with bi-polar disorder] have independently made the discovery that cannabis has improved their conditions, whether the mania or depression. It may also reduce side effects of other drugs used in its treatment, such as Lithium, Carbamazepine (Tegretol) or Valproate (Depakote).

No doubt, cannabis is affecting the balance of neurotransmitters that are at the basis for this disorder.

Endocannabinoids seem to be intimately involved in emotional regulation mechanisms in the limbic system. Because THC and other chemicals in cannabis mimic our own internal biochemistry, they may help replace what is missing."

Dec. 2002 - Ethan Russo, MD 



Bill Zimmerman, PhD, former President of Americans For Medical Rights, wrote in his 1998 book Is Marijuana The Right Medicine For You? A Factual Guide to Medical Uses of Marijuana:

"Using marijuana to treat mood disorders can be very tricky. Since active mood disorders often warp one's observational skills, reports by patients about marijuana lifting them out of depression are inherently unreliable.

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."

1998 - Bill Zimmerman, PhD