Published on: August 22, 2019
by Judy George for MedPage Today:
Higher and rising blood pressure in early middle age was associated with brain volume and white matter brain lesions later in life, a longitudinal study in Britain showed.
High blood pressure (≥140/90 mm Hg) and large increases in blood pressure from ages 36 to 53 were tied to smaller brain volume and more white matter hyperintensities around age 70, reported Jonathan Schott, MD, of University College London, and colleagues in the Lancet Neurology.
“It’s estimated that around 30% of cases of dementia are potentially modifiable now, and while we’re hunting for new treatment for the remaining 70%, we need to be able to optimize as much as we can to prevent dementia in the 30% where there’s a modifiable cause,” Schott said.
“We’ve known for some time that high blood pressure is a potentially modifiable risk factor for dementia, but until recently, what’s been unclear is how hypertension impacts on dementia risk,” he continued. “And, at what stage in your life does having high blood pressure have particular impact on your brain health?”
The study analyzed data from Insight 46, a neuroscience substudy of Britain’s long-running National Survey of Health and Development, a cohort of people born in England, Scotland, and Wales during a single week in 1946. Insight 46 participants have had more than 20 follow-ups since birth, including blood pressure measurements at ages 36, 43, 53, 60 to 64, and 69.
At ages 69 to 71 (mean age 70.7), 465 participants received T1 and FLAIR volumetric MRI, florbetapir amyloid-PET imaging, and cognitive assessments. All were dementia-free and 51% were men.
Higher blood pressure at age 53 and greater increases in blood pressure from ages 43 to 53 were associated with more white matter lesions at ages 69 to 71. A 10 mm Hg higher systolic blood pressure from ages 43 to 53 was associated with 7% more white matter lesions; a 10 mm Hg higher diastolic pressure was tied to 15% more white matter lesions.
Higher blood pressure at age 43 and greater increases in blood pressure from ages 36 to 43 were tied to smaller brain volumes at ages 69 to 71. Each 10-mm Hg increment in diastolic blood pressure at age 43 was associated with a 6.9-mL decrement in brain volume in later life; greater increases in diastolic pressure from ages 36 to 43 were associated with a 6.5-mL decrease in brain volume per one standard deviation change. Greater increases in systolic pressure from ages 36 to 43 were linked to smaller hippocampal volumes later in life.
Blood pressure was not associated with cognition, nor with amyloid pathology on PET. There might not have been enough variability to detect differences in this cognitively normal cohort, observed Lenore Launer, PhD, of the National Institute on Aging, in an accompanying editorial. The researchers also adjusted their findings for early life cognitive performance, “a factor that has been shown previously to be significantly correlated with later life cognitive performance in this cohort; at older ages, changes in cognition might lag behind changes in brain structure,” she noted.
“Although there are several major translational efforts to more completely understand the complexity of blood pressure-cognitive-related outcomes, the simple association between blood pressure and cognitive-related brain pathology is unlikely to be a chance finding,” Launer added.
“Millions of individuals have unhealthy blood pressure. Immediate attention should be given to efforts to control blood pressure through clinical services and public health interventions, and to alleviate the barriers to delivery and uptake of these messages,” she wrote.
The study had several limitations, the researchers noted. Insight 46 participants went through midlife at the same time and were likely to have been exposed to similar hypertension treatments and targets, which may be different for people born in other periods. Insight 46 includes exclusively white British participants; people with a lower socioeconomic position, lower cognition, and more health problems are underrepresented, they added.
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