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Marijuana Use Leads to Earlier Psychosis, Bipolar Disorder


Individuals who use marijuana may develop psychosis nearly 3 years earlier than people who do not indulge in cannabis use, according to a new study to appear in the June print issue of the Archives of General Psychiatry. Another new study notes that regular marijuana use may also trigger bipolar disorder in vulnerable individuals.

Marijuana use linked to earlier mental health problems

The National Institute on Drug Abuse notes that in 2008, a total of 25.8 million Americans age 12 and older had abuse marijuana at least once in the year before they were surveyed. According to the new study in Archives of General Psychiatry, more than 16 million Americans use marijuana regularly, and for some users this could have an effect on psychotic illness.

In fact, authors of the new study note “there is little doubt about the existence of an association between substance use and psychotic illness,” and that investigations have shown “more substance use, especially cannabis use, among people with a diagnosis of a psychotic disorder.”

Psychotic disorders are severe mental conditions that cause abnormal perceptions and thinking and are characterized by hallucinations and delusions. Types of psychotic disorders include schizophrenia and delusions disorder.

Matthew Large, B.Sc (Med), MBBS, FRANZCP, of Prince of Wales Hospital, New South Wales, and colleagues conducted a meta-analysis that included 83 studies and 8,167 patients who had used marijuana or other substances, and 14,352 individuals who had not used these drugs.

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When the researchers compared the age of onset of psychosis between the two groups, they found that people who used marijuana developed psychosis about 2.7 years younger than people who did not use cannabis. The use of any type of substance was associated with the development of psychosis about two years younger.

This study did not identify or explain the relationship between marijuana use and schizophrenia. The authors did note that their findings support the view that use of marijuana precipitates psychotic disorders, and that “reducing cannabis use could delay or even prevent some cases of psychosis.”

In another new study, published in the European Archives of Psychiatry and Clinical Neuroscience, investigators at Oslo University Hospital in Norway, evaluated factors associated with age at onset in bipolar disorder, including use of excessive alcohol or marijuana.

The scientists investigated 151 patients who were receiving psychiatric treatment for bipolar disorder and evaluated their alcohol and marijuana use before and after onset of bipolar disorder. They found that excessive marijuana use was associated with an earlier onset than was excessive alcohol use, regardless of whether drug use preceded or followed onset of bipolar disorder.

Alcohol use was associated with a later onset of bipolar disorder, which suggested it has a different relationship with the disorder than does marijuana. The study’s authors noted that marijuana use may trigger bipolar disorder in people who are vulnerable.

These two studies indicate that marijuana use can lead to earlier onset of psychosis as well as bipolar disorder. The results highlight the potential dangers associated with marijuana use and need to be investigated further.

Large M et al. Archives of General Psychiatry 2011 Feb 7; doi:10.1001/archgenpsychiatry.2011.5
Lagerberg TV et al. European Archives of Psychiatry and Clinical Neuroscience 2011 Jan 26
National Institute on Drug Abuse



...so some topics are taboo then? Narrow-minded approaches to an open debate regarding medical marijuana can never be the right way. I´m not impressed.
It really is just a study report. There is no opinion in this article. Plus, the last sentence reads: "The results highlight the potential dangers associated with marijuana use and need to be investigated further." It is not a biased article at all.
It has also been proven through trial and error in case studies, that indica cannabis helps quell the mania, while sativa helps alleviate the depression in Bi-Polar cases. It's most often a case by case basis, and for some people, it works. I find this research to be a bit biased.
I agree with your comment about it often being a case by case basis, but I just report it. --D. Mitchell
Yes, but the point is your article is extremely biased. You make it sound like it's just marijuana use that is setting off psychosis. But then you slip in there that it's marijuana "and other substances". Not to mention the fact that you can't prove these children weren't self-medicating without doing a long-term study.
This stuff causes people to become psychotic later in life. I know -- I smoked all through 8th grade. I stopped after I started high school because luckily I thought the stoners were losers at that point. After my third year of college at Stanford, in the summer, I became psychotic and have had a problem with depression and psychosis and mild mania ever since. I have been able to maintain euthymia (normal mood for only 1 1/2 to 2 years). There is no history of psychosis or psychosis spectrum disorders in my family. I am positive that smoking pot at such a young age ruined my life and my potential -- I had a full academic scholarship to Stanford -- and was unable to complete it. Parents -- do your children a favor and warn them!!
Kids don't smoke herb then develop mental illness , they smoke because they are self medicating the symptoms of there un-diagnosed disorder. I am speaking through personal experience.
The patients may have had early onset bipolar disorder and attempted to self-medicate.