Abstract Body (Do not enter title and authors here): Introduction: Dementia is increasingly common in older adults, yet limited data exists on its baseline prevalence among those hospitalized with acute coronary syndrome (ACS). This study aims to address that gap by examining the prevalence and subtypes of dementia in older (≥65 years) adults.

Methods: These baseline results are part of a retrospective longitudinal cohort study of Kaiser Permanente Northern California members over age 65 years with ACS hospitalization or stable CAD diagnosis from January 2010 to December 2020. Descriptive statistics were used for baseline demographics and clinical variables including prior comorbidities. The prevalence of dementia at baseline, as well as the distribution of type of baseline dementia, was compared in the ACS hospitalization and non-ACS hospitalization groups using Chi-Square test.
Results: A total of 189136 patients were included with a mean age 75.2 years. Patients hospitalized for ACS were more likely to be female sex (42.6% versus 41.7%, p=0.022), older (76.7 years versus 74.9 years, p<0.001), and present with higher rates of comorbidities based on the Charlson Comorbidity Index (3.1 versus 2.5, p<0.001) compared to patients without an ACS hospitalization. The overall baseline prevalence of dementia was 5.1%. Patients hospitalized with ACS had a significantly higher baseline prevalence of dementia (5.87% versus 4.97%, p<0.0001). Among patients with dementia, the most common subtype was Alzheimer’s disease (AD, 85.4%), followed by vascular dementia (6.4%), Lewy body/Parkinson’s dementia (LB/P, 4.0%), unspecified types (3.8%), and frontotemporal dementia (0.5%), The distribution of dementia subtypes differed significantly with modestly lower rates of LB/P and Vascular dementia in the ACS hospitalization group (p=0.0215, Table 1).

Conclusions: In this large, integrated healthcare cohort, dementia was present in over 1 in 20 older adults in the full cohort, with a significantly higher prevalence among those hospitalized with ACS. AD was the predominant subtype, but small differences in subtype distribution were observed between ACS and non-ACS groups. These findings underscore the importance of recognizing baseline cognitive impairment in the acute cardiovascular care of older adults and may inform future strategies for risk stratification and individualized decision-making.