Prevalence of vascular dementia in a population-based autopsy study in Brazil

INTRODUCTION: Vascular dementia (VaD) is the second leading cause of dementia. However, estimates of VaD prevalence remain uncertain due to lesion heterogeneity, variable clinical presentations, convenience sampling, and limited clinicopathological data, particularly from diverse populations. We aimed to estimate the prevalence of VaD and describe the frequency of cerebrovascular lesions in a population-based autopsy study in Brazil. METHODS: In this autopsy study (2004-2025), inclusion criteria were age at death ≥18 years, presence of a knowledgeable informant, and either a neuropathological diagnosis of VaD or absence of any neuropathological diagnosis. Clinical data were obtained through informant interviews and complemented by a full-body autopsy with detailed neuropathological assessment. Intracranial atherosclerosis was evaluated across Circle of Willis arteries, while hyaline arteriolosclerosis, infarcts, and microbleeds were assessed in 13 brain regions. VaD diagnosis followed the Newcastle categorization, with additional analyses based on modified versions of the Macroscopic Vascular Lesion Score and the Vascular Staging System. RESULTS: The sample comprised 1,718 participants (mean age=69.1±14.2 years; 45% women; 59% White). VaD prevalence was 14% according to the Newcastle categorization, but varied substantially across diagnostic criteria. Among individuals with pure VaD or mixed dementia with a vascular component, 69% exhibited cognitive impairment. One-third of participants with VaD had mixed dementia. Hyaline arteriolosclerosis and lacunar infarcts were more frequent than intracranial atherosclerosis and macroscopic infarcts. CONCLUSION: VaD prevalence was 14%, but varied substantially according to the neuropathological criteria applied. Mixed dementia was frequent, highlighting the co-occurrence of vascular and neurodegenerative pathologies in this diverse Brazilian sample.