Association between microinfarcts and blood pressure trajectories

IMPORTANCE Cerebral microinfarcts are associated with increased risk of cognitive impairment and may have different risk factors than macroinfarcts. Subcortical microinfarcts are associated with declining blood pressure (BP) in elderly individuals. OBJECTIVE To investigate BP slopes as a risk factor for microinfarcts. DESIGN, SETTING, AND PARTICIPANTS From the population-based Mayo Clinic Study of Aging, 303 of 1158 individuals (26.2%) in this cohort study agreed to have an autopsy between November 1, 2004, and March 31, 2016. Cerebral microinfarcts were identified and classified as cortical or subcortical. Baseline and BP trajectories were compared for groups with no microinfarcts, subcortical microinfarcts, and cortical microinfarcts. A secondary logistic regression analysis was performed to assess associations of subcortical microinfarcts with midlife hypertension, as well as systolic and diastolic BP slopes. MAIN OUTCOMES AND MEASURES The presence of cerebral microinfarcts using BP slopes. RESULTS Of the 303 participants who underwent autopsy, 297 had antemortem BP measurements. Of these, 177 (59.6%) were men; mean (SD) age at death was 87.2 (5.3) years. The autopsied individuals and the group who died but were not autopsied were similar for all demographics except educational level with autopsied participants having a mean of 1 more year of education (1.06; 95% CI, 0.66-1.47 years; P <.01). Among 297 autopsied individuals with antemortem BP measurements, 47 (15.8%) had chronic microinfarcts; 30 (63.8%) of these participants were men. Thirty (63.8%) had cortical microinfarcts, 19 (40.4%) had subcortical microinfarcts, and 4 (8.5%) had only infratentorial microinfarcts. Participants with microinfarcts did not differ significantly on baseline systolic (mean difference, −1.48; 95% CI, −7.30 to 4.34; P = .62) and diastolic (mean difference of slope, −0.90; 95% CI, −3.93 to 2.13; P = .56) BP compared with those with no microinfarcts. However, participants with subcortical microinfarcts had a greater annual decline (negative slope) of systolic (mean difference of slope, 4.66; 95% CI, 0.13 to 9.19; P = .04) and diastolic (mean difference, 3.33; 95% CI, 0.61 to 6.06; P = .02) BP. CONCLUSIONS AND RELEVANCE Subcortical microinfarcts were associated with declining BP. Future studies should investigate whether declining BP leads to subcortical microinfarcts or whether subcortical microinfarcts are a factor leading to declining BP.