Cannabis and First-Episode Psychosis: Different Long-term Outcomes Depending on Continued or Discontinued Use

Abstract

Objective: To examine the influence of cannabis use on long-term outcome in patients with a first psychotic episode, comparing patients who have never used cannabis with (a) those who used cannabis before the first episode but stopped using it during follow-up and (b) those who used cannabis both before the first episode and during follow-up. Methods: Patients were studied following their first admission for psychosis. They were interviewed at years 1, 3, and 5. At follow-up after 8 years, functional outcome and alcohol and drug abuse were recorded. Patients were classified according to cannabis use: 25 had cannabis use before their first psychotic episode and continuous use during follow-up (CU), 27 had cannabis use before their first episode but stopped its use during follow-up (CUS), and 40 never used cannabis (NU). Results: The 3 groups did not differ significantly in symptoms or functional outcome at baseline or during short-term follow-up. The CUS group exhibited better long-term functional outcome compared with the other 2 groups and had fewer negative symptoms than the CU group, after adjusting for potential confounders. For the CUS group, the effect size was 1.26 (95% confidence interval [CI] = 0.65 to 1.86) for functional outcome and −0.72 (95% CI = −1.27 to −0.14) for negative symptoms. All patients experienced improvements in positive symptoms during long-term follow-up. Conclusion: Cannabis has a deleterious effect, but stopping use after the first psychotic episode contributes to a clear improvement in outcome. The positive effects of stopping cannabis use can be seen more clearly in the long term.

Brain volume in male patients with recent onset schizophrenia with and without cannabis use disorders

“…51 Although at baseline no differences in clinical characteristics were found between the CUD and NCUD groups, patients who stopped using cannabis had a significantly better functional outcome than patients who never used cannabis and those who con tinued to use cannabis. 51 In summary, these studies show that patients with CUDs could represent a subgroup of pa tients with schizophrenia who have a lower intrinsic vul nerability, but that continued cannabis use in these patients may have neurotoxic effects and is associated with a worse functional outcome. However, for the present cohort no longterm followup data are available, so this theory can not be corroborated by our findings.…”

The disconnect between the science on cannabis and public health campaigns

“…The author pointed towards one type of relevant research, citing the seminal dose-response work of Andréasson [2] while disregarding recent publications on this topic [3,4], as well as other important criteria which have been applied to test causation: prospective studies on the timing of use and psychosis [5]; age of onset of schizophrenia in users versus non-users [6]; percentage exhibiting psychotic symptoms from clinically administered Δ 9 -tetrahydrocannabinol [7]; conversion from temporary to chronic psychosis from cannabis versus other drugs [8]; likelihood of cannabis use in those with a family history of psychosis [9]; cannabis-induced psychosis without such a family history [10]; rates of psychosis in siblings discordant for cannabis [11]; course of recovery from psychotic breaks in non-users versus those who used and quit, or continued use [12]; and whether family history of psychosis affects recovery from cannabis-induced psychotic breaks [13]. Collectively, this literature supports cannabis having a causal impact on chronic psychotic disorders.…”

Experiencias psicóticas atenuadas y consumo de sustancias en universitarios

“…El uso y abuso de sustancias ha sido asociado con un peor curso clínico, un inicio más temprano, una mayor duración de la psicosis sin tratar, exacerbación de la sintomatología, así como un mayor número de recaídas y hospitalizaciones y una peor adherencia al tratamiento, entre otros aspectos (Broussard et al, 2013;González-Pinto et al, 2011;Henquet et al, 2010;Lambert et al, 2005;Stefanis et al, 2014;Wade et al, 2006;Wisdom, Manuel, y Drake, 2011;Zammit et al, 2008). Además, el consumo previo de determinadas sustancias, como por ejemplo el cannabis, parece incrementar el riesgo posterior de desarrollar psicosis, así como las tasas de síntomas psicóticos subclínicos y experiencias psicóticas atenuadas, tanto en población general (Henquet, Murray, Linszen, y Van Os, 2005;Kuepper et al, 2011;McGrath et al, 2010;Moore et al, 2007), como en familiares de pacientes con psicosis (McGuire et al, 1995).…”