Acute effects of smoked marijuana in marijuana smokers at clinical high-risk for psychosis: A preliminary study.

Marijuana use is associated with psychosis, but its effects are understudied in individuals with preexisting risk for psychotic disorders. This preliminary study examined the acute psychological and physiological effects of smoked marijuana (0.0% or 5.5% Δ9 -THC) in marijuana users at clinical high-risk (CHR; n = 6) to develop a psychotic disorder, and those not at risk (n = 6), under controlled laboratory conditions. CHR marijuana users exhibited temporary increases in psychotic-like states and decreases in neurocognitive performance during marijuana intoxication but control marijuana smokers did not. These findings, if replicated, may support a psychotogenic role for marijuana in CHR individuals.