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Original Investigation
April 13, 2020

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

Author Affiliations
  • 1Cognitive Health Services Research Program, Department of Internal Medicine, University of Michigan, Ann Arbor
  • 2Stroke Program, Department of Neurology, University of Michigan, Ann Arbor
  • 3Institute for Healthcare Policy and Innovation, University of Michigan, Ann Arbor
  • 4Johns Hopkins Bloomberg School of Public Health, Department of Epidemiology, John Hopkins University, Baltimore, Maryland
  • 5Department of Physical Medicine and Rehabilitation, University of Michigan, Ann Arbor
  • 6Michigan Alzheimer’s Disease Center, Department of Psychiatry, University of Michigan, Ann Arbor
  • 7VA Ann Arbor Healthcare System, Ann Arbor, Michigan
  • 8Department of Neurology, Vagelos College of Physicians and Surgeons, New York, New York
  • 9Department of Epidemiology, Columbia University Mailman School of Public Health, New York, New York
  • 10Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Columbia University, New York, New York
  • 11Division of General Medicine, Department of Medicine, Columbia University, New York, New York
  • 12Department of Epidemiology, Brown University, Providence, Rhode Island
  • 13Department of Neurology, Johns Hopkins University, Baltimore, Maryland
  • 14Department of Community & Family Medicine, Duke University, Durham, North Carolina
  • 15Johns Hopkins Bloomberg School of Public Health, Department of Health Policy and Management, Johns Hopkins University, Baltimore, Maryland
  • 16Kaiser Permanente Northern California Division of Research, Oakland
  • 17Department of Psychiatry, University of California, San Francisco, San Francisco
  • 18Department of Neurology, University of California, San Francisco, San Francisco
  • 19Department of Epidemiology, University of California, San Francisco, San Francisco
  • 20Department of Neurology, University of Miami, Miami, Florida
  • 21Division of Clinical Research, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland
  • 22Department of Cardiology and Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota
  • 23Department of Internal Medicine, Northwestern University, Chicago, Illinois
  • 24Department of Biostatistics, University of Michigan, Ann Arbor
JAMA Neurol. 2020;77(7):810-819. doi:10.1001/jamaneurol.2020.0568
Key Points

Question  Do black individuals’ higher cumulative blood pressure levels contribute to their greater risk of cognitive impairment and dementia compared with white individuals?

Findings  In this pooled cohort analysis of 19 378 participants, black individuals, compared with white individuals, had significantly faster declines in global cognition. Differences between black and white individuals in global cognition decline were no longer statistically significant after adjusting for cumulative mean systolic blood pressure.

Meaning  Black individuals’ higher cumulative blood pressure levels may explain racial disparities in cognitive decline.

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 Measures  The 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 Relevance  These results suggest that black individuals’ higher cumulative BP levels may contribute to racial differences in later-life cognitive decline.

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