Dementia in older adults with schizophrenia: a 12-year analysis of prevalence, incidence, and treatment patterns in South Korea

Older adults with schizophrenia face a significantly elevated risk of dementia. However, recent trends remain unclear within South Korea's rapidly aging schizophrenia population. This study aimed to quantify the burden of dementia in older schizophrenia patients by examining prevalence, incidence, dementia subtypes, pharmacologic treatment, and healthcare utilization. Using nationwide Health Insurance Review and Assessment (HIRA) data from 2010 to 2021, we identified 220,378 individuals aged ≥50 with schizophrenia. Dementia was diagnosed in 14.6% of patients, with 20.7% of cases occurring before age 60. Patients with dementia were more likely to be female and to have a higher comorbidity burden. Age-standardized all-cause dementia prevalence rose from 11.8% (2010) to 15.8% (2021) in those aged ≥50, and from 24.2% to 32.8% in those aged ≥65-exceeding estimates in the general population. In contrast, incidence declined from 3.4% to 1.7% over the same period. Alzheimer's disease (AD) was the most prevalent subtype (12.2%), followed by vascular dementia (VD, 2.4%), and frontotemporal dementia (0.5%). A lower AD/VD prevalence ratio in schizophrenia (5.3 vs. 8.6 in the general population) suggests a relatively higher burden of vascular pathology. Cognitive enhancer prescriptions increased from 62% to 77% in patients with dementia, compared to 4% to 10% in those without dementia. In 2021, those with dementia were more likely to live in nursing homes (68% vs. 56%) and had greater annual increases in psychiatric hospitalization duration (+2.30 vs. +1.11 days/year). These findings underscore growing care demands and need for integrated treatment strategies for aging schizophrenia patients with dementia.