Does Change in Cannabis Use in Established Psychosis Affect Clinical Outcome?

Abstract

We did not find evidence of an association between cannabis dose and psychotic symptoms, although greater cannabis dose was associated with worse psychosocial functioning, albeit with small effect size. It would seem that within this population, not everyone will demonstrate durable symptomatic improvements from reducing cannabis.

Marijuana: Current Concepts†

“…Self-mutilation can also occur with cannabis-induced psychosis (198). Those with psychosis who use cannabis may not notice improved psychotic symptoms with cessation of their cannabis (199). …”

Continued versus discontinued cannabis use in patients with psychosis: a systematic review and meta-analysis

“…Cannabis is the most commonly used illicit drug in patients with an existing psychotic disorder 1 . In some studies about one out of every four patients with psychosis meet the criteria for cannabis dependence 2,3 with rates of use especially high in young people presenting with their first psychotic episode 2 .…”

“…However, while some evidence suggests that discontinuation of cannabis use may lead to a reduction in readmission rates 21,22 and improvement in symptomatic and functional outcome of psychosis 15,[22][23][24][25][26] , others suggest that this may not necessarily be the case 1,10,27,28 . Although, about 30-50% of cannabis users stop using it after the onset of their psychotic illness 15,[21][22][23]29 suggesting that this may be a clinically relevant issue worth exploring, there is lack of clarity in terms of existing evidence as outlined earlier.…”

Impact of comorbid cannabis use on outcome in first episode psychosis

“…Gender differences in substance abuse, in general, and cannabis abuse, specifically, have been a robust finding in previous research. 5,11,27,28 Consistent with the efficacy of early psychosis intervention, 5,17 patients' positive and negative symptoms decreased from baseline to 24 months. Contrary to our hypothesis, however, we did not find a significant association between cannabis use (no use and abuse/dependence) and decreased positive symptoms at 24 months.…”