Research & Education

Link between high blood pressure in early adulthood and dementia?

A group of researchers is looking at potential associations between elevated blood pressure in younger years and increased risk for dementia. As we wrote about in a past article, links have been established between higher blood pressure at midlife and increased risk for dementia, but this new research aims to determine whether a similar pattern exists when blood pressure is elevated even before midlife.

The research is being conducted at the Medical College of Georgia at Augusta University and is funded by a grant from the National Heart, Lung and Blood Institute. The subjects are 600 individuals (approximately equal numbers Caucasians and African Americans) with an average age of 40, about one-third of whom have hypertension. Medical data exists for some subjects as far back as the previous 23 years. Included in that historical data for some subjects are ambulatory blood pressure and arterial stiffness, plus measures of chronic stress and lifestyle factors. Investigators plan to assess subjects to see if higher blood pressure in earlier life increases risk for dementia, with the increased risk setting in as early as midlife, defined as ages 40-65.

Assessments will be done via MRI, measurements of cerebral blood flow, and cognitive testing. According to a news release from the Medical College of Georgia, “They want to answer questions like whether the arterial stiffness and even atherosclerosis they have already identified in the vasculature of some of these still-young individuals are associated with unhealthy structural and functional changes in the brain as they now reach into midlife.”

One of the investigators said, “We will be able to look at associations between their cardiovascular measures over time and the current status of their cognitive ability, their cerebral blood flow and brain structure.” Hypertension may affect blood flow to the brain, which could have major implications for cognitive function in older age, particularly if the adverse effects on the vasculature are long-term, as would be the case for individuals with hypertension dating back to midlife and before.

By itself, hypertension may be a risk factor for declining cognitive function during aging, but it’s possible that what higher blood pressure may indicate is also a risk factor. Elevated blood pressure is included in the diagnostic criteria for metabolic syndrome, which is driven primarily by chronically elevated insulin, and hyperinsulinemia is a known risk factor for Alzheimer’s disease. In fact, the association between metabolic syndrome and cognitive impairment is so strong that a new term has been coined to encompass both: “metabolic-cognitive syndrome.” (Numerous previous articles have covered the concept of Alzheimer’s disease as “type 3 diabetes,” and the role of impaired brain glucose metabolism as a key element of the illness.)

With this in mind, researchers have posited that if Alzheimer’s is actually a metabolic disease, then reducing risk may require a metabolic approach—perhaps something that has a favorable impact on chronic hyperinsulinemia and metabolic syndrome. To the extent that hypertension is an independent risk factor for cognitive decline, ideally, an effective intervention would also improve blood pressure. Low-carbohydrate and ketogenic diets fit the description for such an intervention. According to Eric Westman, MD, a leading authority on carbohydrate restricted diets, antihypertensive medications may require rapid tapering—as early as within days to weeks of adopting a low-carb or ketogenic diet. Very low-carb diets induce a lowering of insulin levels, which, owing to insulin’s effects on sodium retention, causes a natural diuretic effect. As one example, a 2019 study of patients with insulin resistance showed that dietary carbohydrate restriction led to “substantial and sustained improvements in blood pressure.”

Aside from a change in overall diet, there are numerous nutrients and other compounds that may be beneficial for reducing blood pressure and/or supporting healthy cognition. Polyphenols from blueberries have been shown to improve select parameters of memory and executive function. Medium-chain fatty acids (more commonly called medium-chain triglycerides, or MCTs) are an exciting area of research for supporting cognitive function owing to their rapid conversion to ketones, which may provide the brain with an alternative fuel to glucose. Regarding blood pressure, the amino acid taurine has impressive effects on hypertension, as does arginine. Arginine is a precursor to nitric oxide, which substantially influences vasodilation and endothelial relaxation.