Cannabis and Psychosis

"Although individual lifetime risk of chronic psychotic disorders such as schizophrenia, even in people who use cannabis regularly, is likely to be low (less than 3%), cannabis use can be expected to have a substantial effect on psychotic disorders at a population level because exposure to this drug is so common."

Source: 

Moore, Theresa H M; Zammit, Stanley; Lingford-Hughes, Anne; Barnes, Thomas R E; Jones, Peter B; Burke, Margaret; Lewis, Glyn, "Cannabis use and risk of psychotic or aff ective mental health outcomes: a systematic review," The Lancet (London, United Kingdom: July 28, 2007) Vol 370, p. 327.
http://www.ncbi.nlm.nih.gov...
http://www.thelancet.com...

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