High BP in midlife tied to brain damage in old age

Elevated blood pressure (BP) during midlife is associated with more extensive brain damage in silver years, data from the UK Biobank cohort have shown.

In particular, increase in diastolic BP (DBP) before the age of 50 — even within the healthy range — was linked to broader brain damage in later life. 

To quantify brain damage, the researchers analysed brain lesions known as white matter hyperintensities (WMH), which show up as brighter regions on MRI scans. The regions reflect damage to small blood vessels in the brain and have been associated with an excess risk of dementia, stroke, depression, physical disabilities, and a decline in cognitive function. In addition, WMH have been shown to increase with age and BP.

“Not all people develop these changes as they age, but they are present in more than 50 percent of patients over the age of 65 and most people over the age of 80 even without high BP, but it is more likely to develop with higher BP and more likely to become severe,” explained lead author Dr Karolina Wartolowska from the University of Oxford, UK.

A total of 37,041 participants aged 40–69 years in the prospective community-based UK Biobank cohort, who had WMH data and BP measures available, were included in the analysis. They were assessed by MRI again 4–12 years after baseline. [Eur Heart J 2021;42:750-757]

While high WMH load showed strong association with current systolic BP (SBP; β=0.076, 95 percent confidence interval [CI], 0.062–0.090), the association was strongest for past DBP, especially during the period before age 50 years (β=0.103, 95 percent CI, 0.055–0.152).

The researchers found that WMH load increased by a median 1.126 folds (95 percent CI, 1.107–1.146) for every 10 mm Hg increase in SBP above the normal range, and by 1.106 folds (95 percent CI, 1.090–1.122) for every 5 mm Hg increase in DBP.

Moreover, any increase in BP — even that still below the usual cutoff for treatment of 140 mmHg for SBP and 90 mm Hg for DBP — was associated with increased WMH load, particularly in participants who were taking antihypertensive medications.

“We made two important findings. Firstly, the study showed that DBP in people in their 40s and 50s is associated with more extensive brain damage years later. This means that it is not just the SBP, [but also the DBP,] that is important to prevent brain tissue damage,” said Wartolowska.

”The second important finding is that any increase in BP beyond the normal range is associated with a higher amount of white matter hyperintensities. This suggests that even slightly elevated BP before it meets the criteria for treating hypertension has a damaging effect on brain tissue,” she added.

These results suggest that maintaining BP levels in the healthy range since young age is important for brain health in the long term. 

“The long time interval between the effects of BP in midlife and the harms in later life emphasizes how important it is to control BP [in the] long term, and that research has to adapt to consider the very long-term effects of often asymptomatic problems in midlife,” she highlighted.