Cognitive Function in Individuals With Psychosis: Moderation by Adolescent Cannabis Use

Abstract

Prior cannabis use, compared to nonuse, is reported to be associated with less cognitive impairment in schizophrenia. The age of cannabis use and the persistent influence of cannabis use on cognitive function has not been examined across the psychosis dimension. Ninety-seven volunteers with psychosis (schizophrenia, schizoaffective, or bipolar psychosis) and 64 controls were recruited at the Dallas site of the Bipolar-Schizophrenia Network on Intermediate Phenotypes consortium. Cannabis use history obtained in a semi-structured manner was used to categorize subjects into nonusers, adolescent-onset users, and late-onset users. The a priori hypothesis tested was that individuals with psychosis and a history of adolescent cannabis use (ACU) would have better global neuropsychological performance, as measured by the Brief Assessment of Cognition in Schizophrenia (BACS) battery, compared to those with psychosis and no cannabis use history. BACS Composite scores were significantly higher in individuals with psychosis with ACU compared to individuals with psychosis and no prior cannabis use. In subgroup analyses, ACU influenced global cognition in the schizophrenia/schizoaffective (SCZ) subgroup but not the bipolar psychosis subgroup. Exploratory analyses within the SCZ group, suggest that ACU was associated with better performance in specific domains compared to non-ACU groups. There are distinct associations between age of cannabis use and neuropsychological function across psychotic illnesses. Specifically, ACU is associated with better cognitive function in SCZ but not bipolar psychosis. This age-dependent and diagnosis-specific influence of cannabis may need to be factored into the design of future cognitive studies in SCZ.

Cannabis use in early psychosis is associated with reduced glutamate levels in the prefrontal cortex

“…Moreover, these studies evidenced that the cognitive profile depends on the age at which regular cannabis use begins, and that comorbid cannabis use is associated with a superior cognitive profile only in schizophrenia-spectrum disorders but not in bipolar psychosis (Hanna et al 2016). We failed to replicate these observations, EP users displayed poorer performances in all neuropsychological domains explored, compared both to EP non-users and HC.…”

Cannabis and development of dual diagnoses: A literature review

“…An unexpected and interesting observation linking prior cannabis use in schizophrenia to better cognitive function, compared to individuals with schizophrenia without a cannabis use history, has been reported in many[84, 102–116], but not all studies[117–119]. This is opposite to the pattern observed in cannabis users who are otherwise healthy[120].…”

“…All of these studies show that adolescent cannabis use is associated with improved cognitive function[103, 107, 116, 122–124], contrary to the observation in otherwise healthy controls[125–127]. Two studies with abstinent periods more than one month [103, 108] found that earlier onset cannabis use in schizophrenia was associated with better cognitive function in those with psychosis while the reverse pattern was seen in otherwise healthy controls.…”

Cannabis Legalization: Perceptions of Psychiatrists and Recovering Users

“…Individuals with psychiatric disorders are more likely to use psychoactive substances, with people with schizophrenia having a 10.1% greater chance of using cannabis (Diehl, Cordeiro, & Laranjeira, 2010), however, they are also less likely to develop cognitive symptoms resulting from this use (Hanna et al, 2016). For individuals with aff ective disorders, such as manic episodes, the index reaches 14.5%, 4.1% in individuals with a diagnosis of major depressive disorder, 4.3% with panic disorder, and 2.4% in individuals with phobias (Diehl et al, 2010).…”