1. By comparing the baseline blood pressures and BP trends of elderly individuals with or without subcortical or cortical microinfarcts at autopsy, the authors identified an association between a steeper BP decline and the presence of subcortical microinfarcts.
2. Cortical microinfarcts were associated with the presence of the apolipoprotein E (APOE) ε4 allele, associated with Alzheimer’s disease and amyloid angiopathy.
Evidence Rating Level: 3 (Average)
Study Rundown: Hypotension has been shown to be associated with cognitive impairment and dementia in the elderly, potentially due to microinfarcts and macroinfarcts as a result of cerebral hypoperfusion. Prior studies have assessed cross-sectional BP measurements and the presence of microinfarcts independent of anatomic location. In this study, however, the authors analyze both baseline BP and BP trends over time, and their association with cortical or subcortical infarcts. They used participants from the Mayo Clinic Study of Aging (MCSA) who received serial antemortem BP measurements and obtained data about the presence or absence of microinfarcts at autopsy. No significant differences in baseline systolic or diastolic BP were observed between patients with any, cortical, or subcortical microinfarcts and those without microinfarcts. However, patients with subcortical infarcts at autopsy had steeper annual decline in both systolic and diastolic BP. Additionally, patients with cortical microinfarcts had a greater proportion of APOE ε4 carriers. Mechanistically, declining BP leading to microinfarction may reflect impairment of cerebral autoregulation with age.
This study may have implications for BP targets in the treatment of hypertension in the elderly. However, given that this study is only able to draw associations rather than causations, and also excluded patients with dementia, further studies are warranted to elucidate a potentially causative relationship between BP and microinfarction, and to better understand the role of antihypertensive medications in this phenomenon.
Relevant Reading: Blood pressure and dementia – a comprehensive review.
In-Depth [case-control study]: In this study, the authors used a study cohort of 3395 patients, aged 70 years and older, from the Mayo Clinic Study of Aging (MCSA). Patients participated in antemortem brachial BP measurements and, on autopsy, were evaluated for the presence of microinfarcts, identified as cortical or subcortical, on histologic sections (autopsy cohort, n = 303). Participants with any, cortical, or subcortical microinfarcts did not differ significantly from those without microinfarcts on baseline systolic and diastolic BP. However, participants with subcortical microinfarcts had greater BP decline for both systolic BP (p = 0.04) and diastolic BP (p = 0.02). The group with cortical microinfarcts had a higher proportion carrying the APOE ε4 allele (p = 0.05) compared to the group without microinfarcts. A logistic regression model predicted that for each 1 unit increase in systolic or diastolic slope, the ORs for subcortical microinfarction were 0.94 and 0.90, respectively. Conversely, for each 1 unit decrease in systolic or diastolic slope, the ORs were 1.06 and 1.1, respectively.
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