Cannabis Use and Earlier Onset of Psychosis
Cannabis is the most widely used addictive substance after tobacco and alcohol.
The 2009 National Survey on Drug Use and Health reported that more than 16 million Americans use cannabis on a regular basis,most of whomstarted using cannabis and other drugs during their teenage years.
There is little doubt about the existence of an association between substance use and psychotic illness.National mental health surveys have repeatedly foundmore substance use, especially cannabis use, among people with a diagnosis of a psychotic disorder.
There is a high prevalence of substance use among individuals treated inmental health settings, and patientswith schizophrenia aremore likely to use substances than members of thewider community.
Prospective birth cohort and population studies suggest that the association between cannabis use and later psychosis might be causal, a conclusion supported by studies showing that cannabis use is associated with an earlier age at onset of psychotic disorders, particularly schizophrenia.