Midlife Blood Pressure Tied To White Matter Hyperintensities

People with a history of even mildly elevated blood pressure at midlife are at risk for increased white matter hyperintensities load later in life, a study of UK Biobank data suggests.

Researchers examined data collected on 37,041 UK Biobank participants at enrollment, between March 2006 and October 2010 when they were 40-69 years old (mean age 55.3 years), and at follow-up between August 2014 and October 2019 (mean age 64.1). All the included participants had MRI scans and white matter hyperintensity volume data, and the median time between visits was 9.07 years (range 4.28-13.49 years).

Any increase in blood pressure, even below the typical threshold for intervention of 140 mmHg for systolic and 90 mmHg for diastolic pressure, was associated with increased white mater hyperintensity volume, the study team reports in the European Heart Journal. This was particularly true for people on antihypertensive medication.

For every 10mmHg increase in systolic blood pressure above the normal range, the white matter hyperintensity load increased by a median 1.136-fold. White matter hyperintensities also increased by 1.106-fold for each 5mmHG increase in diastolic pressure.

"Even mildly elevated blood pressure, which does not fulfil the criteria for hypertension, may detrimentally affect the health of brain tissue," said study co-author Dr. Karolina Wartolowska, of the Centre for Prevention of Stroke and Dementia at the University of Oxford in the UK.

It's possible that people who were taking antihypertensive medication had more damage to their brains' white matter because they had a period of elevated blood pressure or hypertension in the past and were prescribed medication to correct this, Dr. Wartolowska said by email.

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Among the top decile for white matter hyperintensity load, 24% of the load could be attributed to systolic blood pressure above 120mmHg, and 7% could be explained by diastolic blood pressure above 70mmHg, the analysis found.

"Many people may think of hypertension and stroke as diseases of older people, but our results suggest that if we would like to keep a healthy brain well into our 60s and 70s, we may have to make sure our blood pressure, including the diastolic blood pressure, stays within a healthy range when we are in our 40s and 50s," Dr. Wartolowska said.

Because even slight increases in blood pressure within a normal range are still associated with more white matter hyperintensities, clinicians may want to consider treating blood pressure even in those who don't meet the clinical criteria for a hypertension diagnosis, Dr. Wartolowska added.

"Our results suggest that to ensure the best prevention of white matter hyperintensities in later life, control of diastolic blood pressure, in particular, may be required in early midlife, even for diastolic blood pressure below 90mmHg, whilst control of systolic blood pressure may be more important in late life," Dr. Wartolowska said.

One limitation of the study is that MRI scans were only available at a single point in time, making it impossible for researchers to directly quantify the progression of white matter hyperintensities, the study team notes.

Further research is also needed to pinpoint differences in distinct regions of white matter and to examine the potential interaction of confounders such as diabetes, smoking, cholesterol, obesity, and kidney disease, researchers point out.

Even so, the study offers fresh evidence of the connection between cardiovascular health and brain health, said Dr. Jeffrey Burns, co-director of the University of Kansas Alzheimer's Disease Center in Kansas City.

"This study suggests that higher blood pressures, even at levels we may consider as normal, are associated with negative brain health findings," Dr. Burns, who wasn't involved in the study, said by email. "This supports the idea that even more aggressive treatment of blood pressure and at earlier ages may further enhance an individual's brain health for the long term."

—Lisa Rapaport

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