The relationship between late-life blood pressure (BP) and damage to the brain is modified by midlife hypertension history, research shows.
“Our study suggests history of midlife hypertension is critical to understand how late-life BP affects brain structure and function”, say Lenore Launer (National Institute on Aging, Bethesda, Maryland, USA) and team.
As reported in Neurology, the researchers studied data on 4057 participants of the Age, Gene/Environment Susceptibility (AGES)–Reykjavik Study. The participants underwent vascular and cognitive screening and magnetic resonance imaging during midlife (average age 50 years) and late life (76 years).
In late life, increasing systolic (S)BP was significantly associated with an increased risk of severe white matter lesions (WMLs) and brain infarcts, and higher diastolic (D)BP was associated with a higher risk of severe WMLs and cerebral microbleeds, but only in participants who did not have hypertension in midlife.
The effect was stronger for small-vessel disease (WMLs and microbleeds) than for large-vessel disease (brain infarcts), which the researchers say could be simply because large-vessel events are often fatal, thus removing participants from the cohort prior to the late-life follow-up.
Among participants with midlife hypertension, the only significant late-life association was between high DBP and severe WMLs. All associations were independent of variables including age, gender and mid- and late-life cardiovascular risk factors.
However, participants with midlife hypertension did have significant associations between lower late-life DBP and smaller total and grey matter brain volume, after adjusting for confounders. Furthermore, these participants’ memory scores, derived from a battery of six cognitive tests, declined in line with increasing late-life DBP, similar to the association with brain volume.
The researchers say there could be several mechanisms behind this association, including reduced resting cerebral blood flow caused by chronic hypertension or the effect of comorbidities for which low DBP is a risk indicator.
“Older people without a history of high blood pressure but who currently have high blood pressure are at an increased risk for brain lesions, suggesting that lowering of blood pressure in these participants might be beneficial”, said Launer in a press statement.
“On the other hand, older people with a history of high blood pressure but who currently have lower blood pressure might have more extensive organ damage and are at risk of brain shrinkage and memory and thinking problems.”
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