Association Between Blood Pressure and Later-Life Cognition Among Black and White Individuals

Abstract

IMPORTANCE Black individuals are more likely than white individuals to develop dementia. Whether higher blood pressure (BP) levels in black individuals explain differences between black and white individuals in dementia risk is uncertain.OBJECTIVE To determine whether cumulative BP levels explain racial differences in cognitive decline. DESIGN, SETTING, AND PARTICIPANTS Individual participant data from 5 cohorts (January 1971 to December 2017) were pooled from the Atherosclerosis Risk in Communities Study, Coronary Artery Risk Development in Young Adults Study, Cardiovascular Health Study, Framingham Offspring Study, and Northern Manhattan Study. Outcomes were standardized as t scores (mean [SD], 50 [10]); a 1-point difference represented a 0.1-SD difference in cognition. The median (interquartile range) follow-up was 12.4 (5.9-21.0) years. Analysis began September 2018. MAIN OUTCOMES AND MEASURESThe primary outcome was change in global cognition, and secondary outcomes were change in memory and executive function. EXPOSURES Race (black vs white).RESULTS Among 34 349 participants, 19 378 individuals who were free of stroke and dementia and had longitudinal BP, cognitive, and covariate data were included in the analysis. The mean (SD) age at first cognitive assessment was 59.8 (10.4) years and ranged from 5 to 95 years. Of 19 378 individuals, 10 724 (55.3%) were female and 15 526 (80.1%) were white. Compared with white individuals, black individuals had significantly faster declines in global cognition (−0.03 points per year faster [95% CI, −0.05 to −0.01]; P = .004) and memory (−0.08 points per year faster [95% CI, −0.11 to −0.06]; P < .001) but significantly slower declines in executive function (0.09 points per year slower [95% CI, 0.08-0.10]; P < .001). Time-dependent cumulative mean systolic BP level was associated with significantly faster declines in global cognition (−0.018 points per year faster per each 10-mm Hg increase [95% CI, −0.023 to −0.014]; P < .001), memory (−0.028 points per year faster per each 10-mm Hg increase [95% CI, −0.035 to −0.021]; P < .001), and executive function (−0.01 points per year faster per each 10-mm Hg increase [95% CI, −0.014 to −0.007]; P < .001). After adjusting for cumulative mean systolic BP, differences between black and white individuals in cognitive slopes were attenuated for global cognition (−0.01 points per year [95% CI, −0.03 to 0.01]; P = .56) and memory (−0.06 points per year [95% CI, −0.08 to −0.03]; P < .001) but not executive function (0.10 points per year [95% CI, 0.09-0.11]; P < .001). CONCLUSIONS AND RELEVANCEThese results suggest that black individuals' higher cumulative BP levels may contribute to racial differences in later-life cognitive decline.

Sex Differences in Cognitive Decline Among US Adults

“…We excluded participants reporting Hispanic ethnicity from NOMAS because other cohorts did not collect information on Hispanic ethnicity or had few participants reporting Hispanic ethnicity; therefore it would be difficult to separate the effect of the NOMAS cohort from the effect of Hispanic ethnicity. We required participants to have 1 or more assessments of cognition and 1 or more measurements of blood pressure (BP) at or before the first measurement of cognition because BP is a risk factor for cognitive decline 11 , 18 and varies by sex. 18 , 19 The University of Michigan institutional review board approved this study.…”

“… 18 , 27 , 28 Long-term cumulative mean systolic BP has improved prediction of clinical outcomes compared with single BP measurements 29 or mean BP over discrete intervals (eg, ≤1 year, 1 to 5 years) before outcome measurement, 28 and time-dependent cumulative mean systolic BP is associated with cognitive trajectories. 11 Cohorts measured current hypertension medication use by evidence of medication bottles and self-report (eAppendix in the Supplement ).…”

“… 9 , 10 Whether cognitive trajectories differ by sex after accounting for sex differences in cardiovascular risk and education levels is unknown. Using a pooled cohort 11 of 5 diverse, well-characterized, population-based cohort studies with repeated objective measures of cognition, we conducted a study to assess sex differences in later-life cognitive trajectories. We hypothesized that women have greater cognitive decline than men after adjusting for potential confounders.…”

Ideal vascular health and cognitive performance in the Brazilian Longitudinal Study of Adult Health

“…The presence of optimal vascular health reduced the gap in cognitive performance amongst the sociodemographic groups. Previous studies suggest that the differences found between Whites and Blacks in the association between vascular health and cognition are probably due to the cumulative effect of early‐onset and poor control of VRFs in Blacks [27,28] These health disparities seem to be largely explained by the racism and lower socioeconomic status (income, education, health access) faced by Black individuals [27] Moreover, participants with low education had worse cognitive performance than those with more education, which is in line with the cognitive reserve theory [29] However, it is interesting to note that a steeper improvement in the global cognitive performance with IVH was observed in low‐educated participants compared to those with more education, which suggests that IVH could be a marker of brain reserve (absence of cerebrovascular lesions) independent of cognitive reserve (education) [29] Neurodegenerative diseases start early in the life course and the vascular burden on brain disease is cumulative and most associated with dementia risk when present in midlife. Interestingly, in young participants (18–30 years old), IVH was related to better processing speed, executive function and memory 25 years later [30] In our study, a more modest association between IVH and cognitive performance was observed in participants <50 years old compared to older individuals.…”

Collaborative Cohort of Cohorts for COVID-19 Research (C4R) Study: Study Design

“…This effort will leverage prior harmonization efforts across C4R cohorts in the TOPMed Project, the NHLBI Pooled Cohorts Study, the BP COG Study, and the CHARGE Working Groups (10, 40, 42, 62-67). Due to their significance to COVID-19 epidemiology, particular emphasis will be placed on harmonizing the large amount of deep pre-pandemic physiologic (40), neurocognitive (68)(69)(70)(71)(72)(73)(74), and imaging-based (75)(76)(77)(78)(79)(80)(81)(82) phenotyping collected within the decade prior to the outbreak using deep-learning (18,(83)(84)(85) and other methods ( Table 4).…”