Temporal association of cannabis use with symptoms in individuals at clinical high risk for psychosis
Received 24 January 2008; received in revised form 6 August 2008; accepted 11 August 2008. published online 22 September 2008.
Abstract
Background
Cannabis use is reported to increase the risk for psychosis, but no prospective study has longitudinally examined drug use and symptoms concurrently in clinical high risk cases.
Method
We prospectively followed for up to 2 years 32 cases who met research criteria for prodromal psychosis to examine the relationship between substance use and clinical measures.
Results
Cases with a baseline history of cannabis use (41%) were older, but did not differ in clinical measures. Longitudinal assessments showed these cases had significantly more perceptual disturbances and worse functioning during epochs of increased cannabis use that were unexplained by concurrent use of other drugs or medications.
Conclusions
These data demonstrate that cannabis use may be a risk factor for the exacerbation of subthreshold psychotic symptoms, specifically perceptual disturbances, in high risk cases.
ABSTRACT