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Blood Pressure Has Nuanced Links With Dementia Risk

August 18, 2019

By Megan Brooks

NEW YORK—Keeping blood pressure in check in mid-life and avoiding low BP in late life both appear linked to a lower risk of developing dementia, according to two new studies.

"While an opportunity exists for blood pressure modification in the prevention of dementia, 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," Dr. Shyam Prabhakaran, chair of neurology at the University of Chicago, writes in an editorial published with the studies online today in JAMA.

"It is imperative that these nuanced effects of blood pressure on brain health inform future therapeutic approaches to prevent dementia," he notes.

Dr. Keenan Walker from Johns Hopkins University and colleagues used the population-based, prospective Atherosclerosis Risk in Communities (ARIC) study to investigate the association of midlife to late-life BP patterns with subsequent development of dementia.

A total of 4,761 adults had BP measurements taken over 24 years at five visits and underwent neurocognitive testing during the fifth and a sixth visit, when 516 new cases of dementia were diagnosed.

Compared with normal BP, hypertension (BP>140/90 mm Hg or use of BP-lowering medication) in midlife (ages 54 to 63 years) was associated with higher risk of late-life dementia (hazard ratio, 1.41; 95% confidence interval, 1.17 to 1.71).

Risk of dementia in late-life was also increased in those with midlife hypertension followed by late-life hypotension (BP<90/60 mm Hg), with a hazard ratio of 1.62 (95% CI, 1.11 to 2.37).

"These findings support previous work which has demonstrated that individuals who have chronic hypertension or elevated blood pressure spanning multiple decades from middle- to late-life have an increased risk for dementia," Dr. Walker told Reuters Health by email. "However, these findings also add to the literature by showing that individuals with a pattern of midlife hypertension that is followed by late-life hypotension (or a significant drop in blood pressure) also show an increased risk for later dementia."

"The current study suggests that maintaining a healthy blood pressure throughout midlife and late-life may be one way to help decrease one's risk of dementia," said Dr. Walker.

In the other study, Dr. R. Nick Bryan from University of Texas at Austin and the SPRINT MIND investigators evaluated ties between intensive between BP lowering and cerebral white matter lesion and brain volumes in a subgroup of 449 participants from the SPRINT MIND study who underwent baseline and follow-up MRI.

Over nearly four years of follow up, intensive BP management to a target of <120 mm Hg (versus <140 mm Hg) was associated with a significantly smaller increase in white matter lesion volume (0.92 cm3 vs. 1.45 cm3).

However, intensive BP lowering was also associated with a significantly greater decrease in total brain volume (between-group difference in change, -3.7 cm3), although the difference was small and the clinical significance of this finding is unclear, the researchers note.

"While targeting Alzheimer 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," Dr. Prabhakaran writes in his editorial.

The "compelling, albeit not definitive, findings from these two studies are encouraging." BP lowering in midlife, if proven as an effective primary prevention strategy, would have "major public health implications," he adds.

"Multimodal approaches that include modification of other vascular risk factors through pharmacologic and lifestyle interventions may have effects additive to blood pressure lowering alone. Indeed, a Finnish trial of diet, exercise, and cognitive training in elderly patients resulted in less cognitive decline than standard management. Another study of lipid management reported that statins could slow the progression of white matter hyperintensities," Dr. Prabhakaran says.

"Based on current guidelines, management of vascular risk factors is warranted for primary prevention; however, 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," Dr. Prabhakaran concludes.

SOURCE: http://bit.ly/33yYmLA, http://bit.ly/33vE5Xt and http://bit.ly/33rzTIl

JAMA 2019.

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