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Two studies looked at the relationship between blood pressure and brain health in JAMA: one reporting MRI data from the SPRINT MIND trial, the other looking at long-term effects of hypertension over several decades.

In the study, hypertensive adults targeted to a systolic blood pressure goal of <120 mm Hg showed a small but significantly lower amount of white matter lesions and a slightly greater decrease in brain volume than people targeted to <140 mm Hg, reported R. Nick Bryan, MD, PhD, of Dell Medical School at the University of Texas at Austin, and colleagues.

In the community-based study, which spanned nearly 2.5 decades, midlife hypertension (blood pressure >140/90 mm Hg) was associated with an increased risk of dementia, as was midlife hypertension followed by late-life hypotension (blood pressure <90/60 mm Hg), wrote Keenan Walker, PhD, of the Johns Hopkins University School of Medicine, and colleagues.

Besides Alzheimer's pathology, there is increasing evidence about the role vascular pathology plays in dementia, observed Shyam Prabhakaran, MD, of the University of Chicago, in an accompanying . "Furthermore, these two common pathologies can coexist in individual patients, with evidence that cerebrovascular insults might even trigger Alzheimer's disease pathology," he wrote.

"While targeting Alzheimer's disease pathology to reduce dementia progression has thus far proven disappointing in clinical trials, the potential for preventing dementia by modifying vascular risk factors has gained momentum," he added.

SPRINT MIND Imaging

SPRINT MIND was a substudy of the randomized SPRINT study, which aimed to determine the effects of intensively lowering systolic blood pressure to <120 mm Hg on the heart, kidney, and brain in hypertensive older adults who did not have diabetes or stroke. The success of SPRINT's -- which raised questions about trial design and how results should be applied -- led to the trial's early termination.

SPRINT MIND researchers previously reported that aggressively lowering blood pressure did not significantly reduce dementia risk, but did lead to a statistically significant 19% reduced risk of mild cognitive impairment (MCI, HR 0.81, 95% CI 0.69-0.95) over 5 years of follow-up.

In the current analysis, MRIs of 449 SPRINT MIND participants showed mean white matter lesion volume in the intensive treatment group increased by 0.92 cm³ over 4 years, which was less than the 1.45 cm³ volume increase in the standard treatment group (between-group difference in change −0.54 cm³, 95% CI −0.87 to −0.20) in the same period.

The intensive treatment group also had a greater decrease in total brain volume (between-group difference in change −3.7 cm³, 95% CI −6.3 to −1.1). This effect, seen mostly in men, was small and of unclear clinical significance, the researchers noted.

"Previous SPRINT papers have documented beneficial effects on the heart of more aggressive management of hypertension, but there remain concerns, mostly anecdotal, that the brain, particularly in older patients, actually needs 'slightly' higher blood pressure for adequate perfusion," Bryan said.

"The SPRINT-MIND papers now provide evidence that more aggressive treatment of hypertension to less than 120 mm Hg systolic blood pressure is not harmful to the brain, but beneficial," he told MedPage Today. "These results support previous SPRINT MIND reports showing that intensive treatment of hypertension may slow cognitive decline in older patients."

ARIC Community Study

The tracked 4,761 participants in four U.S. communities over a 24-year period, assessing blood pressure every five visits and providing a detailed neurocognitive evaluation near the end.

The study examined how blood pressure patterns differentially related to risk for dementia over time, Walker explained. "Given the evidence that midlife and late-life blood pressure may both be important determinants of brain health, the importance of this study lies in its ability to characterize long-term blood pressure patterns across multiple decades and relate these blood pressure patterns to meaningful neurologic outcomes," he told MedPage Today.

Participants who had midlife and late-life hypertension (HR 1.49, 95% CI 1.06-2.08) and midlife hypertension and late-life hypotension (HR 1.62, 95% CI 1.11-2.37) had significantly increased risk of subsequent dementia compared with people who remained normotensive.

Late-life drops in blood pressure were tied to an increased risk of dementia and MCI and "this pattern of low blood pressure during late-life is only associated with increased dementia risk among individuals with hypertension during midlife," Walker said.

These two studies provide important data, but many questions remain, Prabhakaran noted. "Uncertainties still exist in the care of asymptomatic patients with moderate to severe subclinical cerebrovascular disease changes on brain imaging or known large-artery disease such as carotid or intracranial stenosis," he wrote. Managing vascular risk factors would be warranted based on current guidelines, but "the optimal targets for blood pressure are unknown in this group of patients, in whom relative hypotension may result in further ischemic damage and increase the risk of dementia and stroke."

While both studies suggest opportunities to modify blood pressure for dementia prevention, "earlier, midlife management may be optimal, and later blood pressure-lowering interventions require careful monitoring for the potential cognitive harm associated with late-life hypotension," he added. "It is imperative that these nuanced effects of blood pressure on brain health inform future therapeutic approaches to prevent dementia."