Long Term Cognitive Sequelae of Adolescent Cannabis Use in Individuals with Psychosis



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BACKGROUND: Cognitive deficits are well established in schizophrenia and there is evidence of an association between adolescent cannabis use and cognitive function in schizophrenia. This study examined the relationship between age of cannabis use and cognition in individuals within the psychosis domain, including those with schizophrenia, schizoaffective disorder and bipolar disorder with psychosis. SUBJECTS: Archival data from the University of Texas Southwestern Medical Center (UTSW) site of the Bipolar-Schizophrenia Network on Intermediate Phenotypes (B-SNIP) study. Participants included probands with schizophrenia, schizoaffective disorder, bipolar disorder with psychotic features, and healthy controls with and without a history of cannabis use.
METHOD: The psychosis (N=97) and control (N=64) groups were divided into six groups: control with no cannabis use (CCB-; N=38), control with adolescent cannabis use (CCB+; N=16), control with late cannabis use (N=10), psychosis with no cannabis use (PCB-; N=48), psychosis with adolescent cannabis use (PCB+; N=33), and psychosis with late cannabis use (N=16). All participants completed the Brief Assessment of Cognition in Schizophrenia (BACS) neuropsychological battery, the Birchwood Social Functioning Scale, Structured Clinical Interview for DSM-IV diagnosis, Positive and Negative Symptom Scale, as well as a detailed record of patterns of substance use including age of onset, period and frequency of greatest consumption, and most recent use. RESULTS: Regarding cognitive function, this thesis found that age of cannabis use impacted the BACS total score. Specifically, the control and psychosis adolescent cannabis use groups were not significantly different in cognitive functioning. PCB+ performed better than the other psychosis groups, and CCB+ performed worse than the other control groups. Additionally, PCB+ and PCB- were significantly different, with the PCB+ performing better cognitively. DISCUSSION: There is previous evidence suggesting that individuals with schizophrenia and adolescent cannabis have less neuropsychological impairment compared to individuals with schizophrenia who do not have a cannabis use history. In this thesis, we extended these findings to psychosis as a spectrum, finding that individuals with psychosis and adolescent cannabis use had better overall cognition as measured by a brief neurocognitive test battery compared to those with psychosis and no cannabis use history.

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