Higher prevalence of dementia in patients with schizophrenia: A nationwide population-based study.

IntroductionThis study investigates the prevalence of dementia in patients with and without schizophrenia, with a particular focus on age-specific and sex-specific differences. MethodsWe conducted a population-based study using the National Health Insurance claims database from 2010 to 2013. Using a 10:1 matching ratio, 248,919 patients without schizophrenia and 26,591 patients with schizophrenia were identified based on the ICD-10 code. Patients with dementia were extracted by diagnosis or use of anti-dementia drugs. Conditional logistic regression analyses were performed to evaluate the association between schizophrenia and dementia. ResultsThe prevalence of dementia was significantly higher in schizophrenia patients compared with that in matched non-schizophrenia patients (9.9% versus 2.2%, P<0.0001). After adjusting for Charlson comorbidity index and underlying comorbidities, conditional logistic regression showed that schizophrenia was associated with dementia (adjusted odds ratio [AOR], 4.7; 95% confidence interval [CI], 4.4-5.1). When stratified by sex, the AOR was 5.6 (95% CI, 5.0-6.2) among women and 4.0 (95% CI, 3.6-4.5) among men. Moreover, the association between dementia and schizophrenia was strong in elderly patients. The AOR of dementia prevalence was 6.6 (95% CI, 6.1-7.2) in patients aged 65years and 3.4 (95% CI, 3.0-3.8) in patients aged <65years. DiscussionSchizophrenia patients were more likely to have dementia compared with non-schizophrenia patients. This association seems greater in higher prevalence groups such as women and patients aged 65years. Further investigation on the mechanism is required. (c) 2016 John Wiley & Sons Australia, Ltd