The Hispanic population aged >65 years old is projected to more than triple by 2060, at which point it will represent 20% of all Americans over the age of 65.1 In anticipation, now is the time to investigate modifiable risk factors for dementia specific to Hispanic individuals. A large histopathologic study of patients with dementia showed that a burden of cerebrovascular disease sufficient to contribute to dementia was present in 54% of Hispanic subjects versus 28% of non-Hispanic white and 40% of non-Hispanic Black patients.2 Additional research has highlighted the importance of cardiovascular risk factors, principally hypertension, in Hispanic patients’ risk of dementia.3 Based on this research, we hypothesized that higher blood pressure would increase the risk of developing dementia or mild cognitive impairment in Hispanic more than non-Hispanic patients.
We performed an exploratory post-hoc analysis of the SPRINT MIND study, using a publicly available deidentified dataset supplied by NHLBI that did not require IRB approval.4 The primary outcome was the composite of probable dementia or MCI (dementia/MCI) and primary predictor was self-identified Hispanic versus non-Hispanic ethnicity. We defined the exposure period, during which blood pressures were collected, as the first 600 days of the SPRINT trial. Outcomes were recorded during the subsequent SPRINT follow-up. We fit Cox proportional hazards models to our outcome and adjusted for age, sex, race (White vs. Black vs. other), diabetes, education, physical activity, and smoking status. We verified that the proprotional hazards assumption of our Cox model was met.
We included the interaction of mean systolic blood pressure (mSBP)#ethnicity (Hispanic vs. non-Hispanic) in our model and then stratified by ethnicity. We used marginal effects after multivariable logistic regression to determine the predicted probability of dementia/MCI across mSBP levels.
We included 8,484 patients, of which 882 (10.4%) were Hispanic and 7,602 (89.6%) were non-Hispanic. The mean (SD) age was 67.9 (9.3) years, 64.8% were male, and the mean (SD) number of SBP measurements during the exposure period was 19.2 (5.6). There was an average of 2.98 years of follow-up and 863/8,484 (10.2%) developed dementia/MCI, which was more common in Hispanic (123/882, 14.0%) than non-Hispanic (740/7,602, 9.7%) patients (p<0.001). In non-Hispanic White patients, the rate of dementia/MCI was 8.8% (439/4,981) and in non-Hispanic Black patients it was 11.5% (286/2,498).
The mSBP was lower in Hispanic than non-Hispanic patients (127.5 vs. 128.7 mm Hg, p<0.001), and the interaction between mSBP#ethnicity had a p value <0.1 (p=0.053), indicating that mean systolic blood pressure affected the risk of dementia/MCI differently in Hispanic vs. non-Hispanic patients. After stratification by Hispanic ethnicity, for every 10 mm Hg increase in mSBP the hazard ratio for dementia/MCI in Hispanic patients was 1.27 (95% CI, 1.08–1.50), while for non-Hispanic patients it was 1.08 (95% CI, 1.00–1.16). The relationship between mSBP and ethnicity is shown in Figure 1. For example, in a Hispanic patient with a mSBP of 130 mm Hg, the predicted probability of dementia/MCI was 16.1% (95% CI, 13.3–18.8), while for a non-Hispanic patient with the same mSBP the predicted probability was 9.6% (95% CI, 9.0–10.2).
Figure 1.
In a post-hoc analysis of the SPRINT-MIND trial, we found that higher mean systolic blood pressure had a larger association with incident dementia or MCI in Hispanic than non-Hispanic patients. While limited by unmeasured confounding and enrollee selection bias, these findings are similar to prior research demonstrating the importance of hypertension on the risk of cognitive impairment in Hispanic patients.2,3 Because hypertension is a modifiable risk factor, we propose that a SBP goal of ≤120 mm Hg may be particularly important for the cognitive health of Hispanic adults. As demonstrated by the Cut Your Pressure Too trial in barbershops,5 blood pressure trials designed specifically for minority populations can yield meaningful results. Similar population-specific trials could be designed to improve blood pressure control among Hispanic populations that cumulatively form a growing segment of the US population.
Acknowledgments:
We acknowledge NHLBI and the SPRINT investigators for making the trial’s dataset publicly available. We would also like to acknowledge Dr. Clinton B. Wright from NIH/NINDS for providing us with his guidance and expertise on this topic. This article was prepared using the SPRINT Research Materials obtained from the NHLBI Biologic Specimen and Data Repository Information Coordinating Center and does not necessarily reflect the opinions or views of SPRINT MIND or the NHLBI.
Sources of Funding:
Dr. de Havenon is supported by NIH-NINDS K23NS105924; Dr. Sheth by NIH-NINDS U01NS106513, R01NS11072, R01NR018335, R03NS112859, U24NS107215, U24NS107136, and American Heart Association 17CSA33550004.
Disclosures:
Dr. de Havenon has received investigator initiated clinical research funding from Regeneron and AMAG pharmaceuticals. Dr. Sheth reports funding from Biogen, Novartis, Bard, Hyperfine, Astrocyte, Alva Health. Dr. Toyoda reports personal fees from Daiichi-Sankyo, Bayer Yakuhin, Bristol-Myers-Squibb, Takeda, and Nippon Boehringer-Ingelheim.
Contributor Information
Adam de Havenon, University of Utah Department of Neurology.
Mohammad Anadani, Washington University School of Medicine in St. Louis.
Eric Stulberg, University of Utah Department of Neurology.
Natalia Rost, Harvard Medical School Department of Neurology.
Shyam Prabhakaran, University of Chicago Department of Neurology.
Kevin N. Sheth, Yale University Department of Neurology.
References
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