A new study published in the Archives of General Psychiatry says that using marijuana, or cannabis, may cause psychosis to develop sooner in patients already predisposed to developing the condition. In other patients it may even cause psychosis.

The study was led by Australian researchers, who analyzed data from 83 studies involving more than 20,000 patients. One important finding is that cannabis users experienced psychosis three years younger than non-users. Users of substances other than cannabis experienced symptoms two years earlier. The study found alcohol had no influence on the development of psychosis. Read more here.

As those with mentally ill loved ones may know, psychosis can result in losing touch with reality and hallucinations and/or delusions about what is going on around one. Psychosis is frequently seen in patients with schizophrenia and bipolar disorder.

The study says, “An extra two or three years of psychosis-free functioning could allow many patients to achieve the important development milestone of late adolescence and early adulthood that could lower the long-term disability arising from psychotic disorders.”

In a similar 2010 study, lead author John McGrath, a professor at the Queensland Brain Institute in Brisbane, Australia, told Businessweek, “The earlier you use cannabis, the more likely you are to have symptoms of a psychotic illness.”*

Both Australian studies support the conclusions of a Danish study published in the December 2005 issue of the British Journal of Psychiatry. While researchers in this study did not find their results proved marijuana was directly linked to schizophrenia, there was some evidence it might hasten the onset of the disorder. The study also found subjects who developed schizophrenia after cannabis use did so at an earlier age than comparison subjects.

Mikkel Arendt, Ph.D., a fellow at the Center for Basic Psychiatric Research at the University of Aarhus in Denmark said in an interview with Psychiatric News, “I think it is important to follow the patients treated for cannabis-induced psychosis closely and offer them and their relatives information on risk factors for and early signs of schizophrenia.”

Arendt continued, “The prognosis of patients improves with early intervention. An episode of short-lived psychotic symptoms following cannabis use seems to have great prognostic value.”**

* Businessweek, Long-Time Marijuana Use Linked to Psychosis in Young Adults, February 26, 2010
** Psychiatry News, Marijuana-Induced Psychosis May Fortell Future Episodes, February 3, 2006

Pasadena Villa offers adult residential treatment to mental health patients with Dual Diagnosis, addressing both emotional disorders and substance abuse.  Our Social Integration Model helps individuals with a dual diagnosis by providing an integrated, comprehensive approach to both the emotional disorders and the substance abuse. If you are the caretaker or family member of an adult or young person with a mental illness, please call us at 877-845-5235 or contact us online.

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Mental Illnesses by the Pasadena Villa Team