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.
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