New Study: Marijuana Users Less Depressed - November 17, 2005
Largest-Ever Study of Marijuana, Depression Finds Fewer Depressive Symptoms, Better Mood

ALBANY, NEW YORKâ??In the largest-ever study of marijuana and depression, to be published in the journal Addictive Behaviors, daily or weekly marijuana users had fewer symptoms of depression than non-users. Marijuana users were also more likely to report positive moods and fewer somatic complaints such as sleeplessness. Noteworthy differences were also found between those using marijuana for medical purposes and non-medical or "recreational" users.

The new research appears to contradict statements by some government officials suggesting that marijuana is a cause of depression. For example, in a May 3, 2005, press release from the White House Office of National Drug Control Policy, ONDCP Director John Walters said, "Marijuana use, particularly during the teen years, can lead to depression, thoughts of suicide and schizophrenia."

"Not only does marijuana not cause depression, it looks like it may actually alleviate it," said Mitch Earleywine, co-author of the new study and associate professor of psychology at the University at Albany, State University of New York.

Earleywine and co-investigator Thomas F. Denson of the University of Southern California used an Internet questionnaire that allowed them to survey a very large sample of marijuana users and non-users, totaling over 4,400 participants. Use of the Internet also made it possible to include highly depressed or marijuana-involved participants who might be unable or unwilling to participate in in-person or telephone surveys.

Participants were asked to report their use of marijuana and were divided into three categories: daily users, those who used marijuana within the last month but no more than once per week (weekly users) and those who had never used marijuana in their lifetime (non-users). Depression and related issues were assessed using the Center for Epidemiologic Studies Depression scale, a standard tool for researching depression and associated symptoms.

Both daily and weekly marijuana users had significantly lower levels of depression and higher levels of positive mood than non-users. Weekly users also had lower levels of somatic complaints such as sleeplessness. Effects were generally large, with marijuana users approximately 30% less depressed than non-users.

The study is the first to specifically look at depression in medical marijuana users as compared to non-medical users. The most common complaints listed by medical users surveyed were nausea, vomiting, cancer, attention deficit and poor appetite. Medical users generally were more depressed and had more somatic complaints than non-medical users, but still reported fewer such symptoms than non-users.

"Those who use marijuana to battle the symptoms of illness may be depressed because of their illness, not because of marijuana," Earleywine said. "Studies that do not identify medical use might falsely implicate marijuana, rather than sickness, as the cause of depressed feelings."

The new study adds to a growing body of knowledge suggesting that marijuana's active components, called cannabinoids, may be beneficial in certain psychological disorders. In a review published this May in the Journal of Psychopharmacology, researchers form the University of Newcastle upon Tyne in Great Britain noted, "Patient reports and observations, backed by known pharmacology, suggest that the cannabis derivatives delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) may have mood stabilizing properties," including anti-depressant and anti-anxiety effects.

"Drug Czar John Walters has tried to frighten Americans about marijuana, using exaggerated and incomplete data cherry-picked to support his ideology," said Rob Kampia, executive director of the Marijuana Policy Project in Washington, D.C. "Science should be used to inform policy, not manipulated to scare the public."

With more than 18,000 members and 120,000 e-mail subscribers nationwide, the Marijuana Policy Project is the largest marijuana policy reform organization in the United States. MPP works to minimize the harm associated with marijuanaâ??both the consumption of marijuana and the laws that are intended to prohibit such use. MPP believes that the greatest harm associated with marijuana is imprisonment. For more information, please visit http://www.MarijuanaPolicy.org.

REFERENCE: Denson, Thomas F. and Earleywine, Mitchell, "Decreased Depression in Marijuana Users," Addictive Behaviors, in press, available at http://www.sciencedirect.com/science/journal/03064603.
http://www.mpp.org/releases/nr20051117.html