994 Cannabis Use a Predictor for Schizophrenia

Whether caused by alcohol or drugs, messing up a teen-ager’s developing brain seems to have life long effects. Such a pity, since they know everything by 16, right?

“Per Dr. Murray, individuals with psychotic symptoms use 2 to 3 times as much cannabis as the general population. There is, however, a question of cause vs effect: that is, does cannabis use increase the risk of psychosis or do those with psychosis choose to use cannabis in order to reduce the impact of their psychotic symptoms?

Dr. Murray quoted prior research supporting the concept that cannabis use is a cause for schizophrenia. In one study of Swedish army recruits followed over 15 years, high consumers of cannabis were 6 times as likely as noncannabis users to develop schizophrenia. This included analyses adjusting for other psychiatric illnesses and social background.[9] Also, in a recently published study of a birth cohort of children followed over 25 years, daily users of cannabis had 1.6 to 1.8 times the rates of psychotic symptoms compared with nonusers.[10] In another study, those who were cannabis users by age 18 years were 1.65 times as likely to have schizophrenia by age 26 years.[11] If they used cannabis by age 15 years, they were 4.5 times as likely to develop schizophrenia by age 26 years.”

Highlights of the American Psychopathological Association Meeting, March 3-5, 2005 as reported at http://www.medscape.com/.