WebMD Medical News Laura J. Martin, MD Feb. 7, 2011 -- People
who smoke pot are more likely to develop a psychotic illness
such as schizophrenia earlier than those who do not use
marijuana, according to a new analysis. The results are
published online in the Archives of General Psychiatry. The
researchers analyzed 83 studies comprising 8,167 people with a
psychotic illness who used marijuana or other psychoactive
substances and 14,352 with a psychotic illness who did not.
Those who used marijuana were close to three years younger when
they developed a psychotic illness such as schizophrenia
compared with those who did not use marijuana. People who used
any type of illicit substances (including, but not limited to
marijuana), were two years younger when they were diagnosed with
a psychotic illness than their drug-free peers. Alcohol use had
no bearing on the age of onset of psychotic illness, the study
shows. “It is increasingly clear that marijuana is a cause of
schizophrenia, and that the schizophrenia cause