A recent study from the Journal of the American College of Cardiology, conducted by Dr. Wuxiang Xie and colleagues, examined the association of blood pressure with cognitive decline, dementia, and mortality [1]. This study included two cohorts: the English Longitudinal Study of Ageing (ELSA) and the Health and Retirement Study (HRS).
In this analysis, 7,566 participants with healthy cognition from ELSA and 9,294 from the HRS were included. When combined, the average age was 63.5 years old. The ELSA cohort was 55.2% female, and the HRS cohort was 59.8% female. Blood pressure was collected at three different study visits for the ELSA cohort and at two different visits for the HRS cohort.
Blood pressure and cognitive decline
Higher systolic and pulse pressures were associated with increased global cognitive decline, while diastolic blood pressure was, in general, inversely associated with cognitive decline. However, people in the ELSA cohort with high diastolic blood pressure had a higher risk of cognitive decline than people with approximately 80 mm Hg of diastolic pressure.
Blood pressure and dementia
588 people in ELSA and 1,764 people in the HRS were reported to have developed dementia during these studies. Increased systolic blood pressure and pulse pressure were associated with an increased risk of dementia. An inverse association was shown with diastolic blood pressure, although a level of above approximately 80 mm Hg showed no benefit in either cohort.
Blood pressure and all-cause mortality
459 deaths in ELSA and 1629 deaths in the HRS were reported. Higher pulse pressure was associated with higher mortality rates in both cohorts. An inverse association was shown between cumulative diastolic blood pressure and mortality, but as with many of the previous results, higher diastolic pressure than approximately 80 mm Hg was not shown to have any benefit.
Conclusion
This study shows that blood pressure is linked to cognitive outcomes and that people with consistently elevated systolic and total pulse pressure are more likely to experience accelerated cognitive decline. The authors note that it is worthwhile to track pulse pressure over time.
The results of this study regarding diastolic pressure differ from the CARDIA study done in younger adults. This may be explained by atrial stiffness and left ventricular hypertrophy, which can occur with consistently elevated blood pressure and lead to lower diastolic pressure [2,3].
The authors list multiple limitations of their study. The participants from both cohorts were predominately white, so its results may not be applicable to all demographic groups. The authors also note that some of the cognitive tasks may have lacked sensitivity in detecting small cognitive changes. Between the two cohorts, there were some discrepancies between measurements of executive function, which may have affected the total cognition results. Finally, due to the observational nature of this study, causal relationships cannot be determined.
The authors conclude their the study with:
We found that long-term cumulative BP was associated with subsequent cognitive decline, risk for incident dementia, and all-cause mortality among cognitively healthy adults >50 years of age. For middle-aged and older individuals, efforts may be required to control long-term systolic blood pressure and simultaneously maintain adequate diastolic blood pressure, with additional attention on controlling long-term pulse pressure warranted; this could be beneficial to both neurocognition and longevity.
Literature
[1] Li, C., Zhu, Y., Ma, Y., Hua, R., Zhong, B., & Xie, W. (2022). Association of Cumulative Blood Pressure With Cognitive Decline, Dementia, and Mortality. Journal of the American College of Cardiology, 79(14), 1321–1335. https://doi.org/10.1016/j.jacc.2022.01.045
[2] Jefferson, A. L., Cambronero, F. E., Liu, D., Moore, E. E., Neal, J. E., Terry, J. G., … & Carr, J. J. (2018). Higher aortic stiffness is related to lower cerebral blood flow and preserved cerebrovascular reactivity in older adults. Circulation, 138(18), 1951-1962.
[3] Lauer, M. S., Anderson, K. M., & Levy, D. (1991). Influence of contemporary versus 30-year blood pressure levels on left ventricular mass and geometry: the Framingham Heart Study. Journal of the American College of Cardiology, 18(5), 1287-1294.
