INTERPRETATION Continued cannabis use after onset of psychosis predicts adverse outcome , including higher relapse rates , longer hospital admissions , and more severe positive symptoms than for individuals who discontinue cannabis use and those who are non-users .
BACKGROUND Although the link between cannabis use and development of psychosis is well established , less is known about the effect of continued versus discontinued cannabis use after the onset of psychosis .
We aim ed to summarise available evidence focusing on the relationship between continued and discontinued cannabis use after onset of psychosis and its relapse .
Marijuana effects on human forgetting functions.
It has long been known that acute marijuana administration impairs working memory ( e.g. , the discrimination of stimuli separated by a delay ) . The determination of which of the individual components of memory are altered by marijuana is an unresolved problem . Previous human studies did not use test protocol s that allowed for the determination of delay-independent ( initial discrimination ) from delay-dependent ( forgetting or retrieval ) components of memory . Using methods developed in the experimental analysis of behavior and signal detection theory , we tested the acute effects of smoked marijuana on forgetting functions in 5 humans . Immediately after smoking placebo , a low dose , or a high dose of marijuana ( varying in delta9-THC content ) , subjects completed delayed match-to- sample testing that included a range of retention intervals within each test session ( 0.5 , 4 , 12 , and 24 s ) . Performances ( discriminability ) at each dose were plotted as forgetting functions , as described and developed by White and colleagues ( White , 1985 ; White & Ruske , 2002 ) . For all 5 subjects , both delta9-THC doses impaired delay-dependent discrimination but not delay-independent discrimination . The outcome is consistent with current nonhuman studies examining the role of the cannabinoid system on delayed matching procedures , and the data help illuminate one behavioral mechanism through which marijuana alters memory performance
INTERPRETATION Continued cannabis use after onset of psychosis predicts adverse outcome , including higher relapse rates , longer hospital admissions , and more severe positive symptoms than for individuals who discontinue cannabis use and those who are non-users .
BACKGROUND Although the link between cannabis use and development of psychosis is well established , less is known about the effect of continued versus discontinued cannabis use after the onset of psychosis .
We aim ed to summarise available evidence focusing on the relationship between continued and discontinued cannabis use after onset of psychosis and its relapse .