6.1 CIGARETTE SMOKING IN SCHIZOPHRENIA IS ASSOCIATED WITH WORSE COGNITIVE FUNCTIONING, SUICIDE ATTEMPTS, AND PREMATURE MORTALITY

Abstract

Background: Individuals with schizophrenia are approximately three times more likely to smoke cigarettes than those in the US general population. Individuals with schizophrenia who smoke are also heavier smokers than smokers in the general population and have a more difficult time quitting. Observational data have contributed to the idea that smoking may serve as a form of "self-medication" for cognitive deficits and emotional distress experienced by individuals with schizophrenia. We present updated and previously-unpublished data from two cohorts about the association between smoking and cognitive functioning, and smoking and suicide attempts in this population; we also report on the prospective association between smoking and natural cause mortality in an additional cohort. Method(s): The first cohort consisted of 861 individuals with schizophrenia, 587 non-psychiatric controls, and 450 individuals with other serious mental illnesses (SMI). Cognitive functioning was assessed with the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). The second cohort consisted of 253 individuals with schizophrenia or other SMI who were assessed with the Columbia Suicide Severity Rating Scale. The third cohort consisted of 789 individuals with schizophrenia who were assessed and then followed up as to their mortality and cause of death after an average period of 8 years. In all of the cohorts, participants were assessed as to their current cigarette smoking status. Within each sample, linear regression models were constructed to determine whether cigarette smoking was associated with the outcome of interest after adjusting for relevant covariates. Result(s): In the first cohort, smoking was significantly and inversely associated with the total RBANS cognitive score for the overall sample (coefficient=-. 176, p=.002) and the schizophrenia group (coefficient= -.282, p=.001) when adjusting for age, sex, race, and maternal education as a proxy for premorbid SES. Within the schizophrenia group, a significant and inverse association was found for the RBANS Immediate Memory (coefficient=-.276, p=.003), Visual Constructional (coefficient=-.227, p=.003), and Attention (coefficient=-.237, p=.005) scales, but not Delayed Memory or Language scales. The associations between smoking and cognitive functioning were largely unchanged when also adjusting for psychiatric symptom severity. Within the second cohort, current smoking significantly associated with a history of suicide attempts in the overall group (OR=2.80, p