Teen Pot Use Linked To Psychoses

An Australian study of nearly 4,000 young people has found a possible link between long-term marijuana use and increased risk of hallucinations, delusions and other psychoses.

In the study, whose findings were released Monday, March 1, 2010, and published in the journal Archives of General Psychiatry, researchers at the University of Queensland followed 3,801 people born in Brisbane between 1981 and 1984.

About 17.7 percent reported using cannabis for three or fewer years, 16.2 percent for four to five years and 14.3 percent for six or more years.
Those who had six or more years of use were twice as likely as those who never used cannabis to develop a psychosis, such as schizophrenia, and four times as likely to get high scores in clinical tests of delusion.

Of the 1,272 subjects who had never used marijuana, 26 (2 percent) were diagnosed with psychosis. Of the 322 who had used it for six years or more, 12 (3.7 percent) were diagnosed with the illness.

The authors point out that further study is needed as their research did not take into account such factors as family history and a predisosition to psychosis before marijuana use began.

For more details see The Archives of General Psychiatry.