LACUNAR INFARCTS: A KEY NEUROPATHOLOGICAL FEATURE IN MILD COGNITIVE IMPAIRMENT

Abstract

The underlying neuropathological lesions associated with mild cognitive impairment (MCI) are not yet completely understood. Differences in individual characteristics between MCI and cognitively normal individuals could help to explain the cognitive impairment on that group. A post-mortem study evaluating individuals included in the Brain Bank of the Brazilian Aging Brain Study Group, Brazil. The clinical diagnosis was established through a postmortem interview with an informant using the Cognitive Dementia Rating (CDR). Individuals with a CDR score of 0 (n=204) and 0.5 (n=51) were included. Individuals who were alcoholics, bedridden or showed severe visual and/or auditory deficits were excluded from the study. Neuropathological examinations were carried out based on accepted criteria, using immunohistochemistry. We compared the frequency of neurofibrillary tangles, neuritic plaques, lacunar infarct, hyaline arteriolosclerosis, cerebral amyloid angiopathy, hippocampal sclerosis, synucleinopathy, and siderocalcinosis between groups, using logistic regression models, adjusted for age, sex, and education. We also described the frequency of neuropathological diagnoses in each group. CDR 0.5 participants (mean age: 72.7±10.6) were 47% male, 55% White, and had mean education of 3.8±2.9 years, while those cognitively normal (mean age: 67.7±10.5) were 54% male, 70% White, and had education of 5.4±4.1 years (Table 1). Compared to cognitively normal, the CDR 0.5 individuals had higher odds of lacunar infarct (OR=3.39, 95%CI=1.19–9.62) (Table 2). The difference between the groups remained after adjusting for age, sex and educational level. The presence of lacunar infarcts was registered in 16% of the CDR 0.5 group, against 4.5% of cognitively normal individuals (Table 3). Among the 51 participants with CDR=0.5, 84% met criteria for a neuropathological diagnosis, with vascular dementia as the most common diagnosis (n=16; 31%). Among 204 cognitively normal participants (CDR=0), 105 (51%) met criteria for a neuropathological diagnoses, with PART definitive as the most common one (n=59; 29%) (Table 4). This study corroborates findings of series with predominantly Caucasians of high educational level, pointing the role of lacunar infarct in impairing the cognition. As vascular risk factors associated with lacunar infarct are preventable, aggressive measures to reduce these factors may impact the prevalence of cognition associated dysfunction.