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Scientists Begin Exploring The Dynamics Of Hypertension And Dementia

Studies published over the last few years have produced evidence that hypertension (high blood
pressure) during midlife appears to increase the risk of dementia and cognitive decline.
Hypertension affects an estimated 1 in 3 adults in the U.S., so it is vital to understanding the
the exact relationship between blood pressure and the aging brain.
Researchers have done work to investigate the links between blood pressure during later life and
cognitive outcomes. However, as the authors of a recent study explain, the findings hint that
optimal blood pressure ranges for older adults may depend on earlier blood pressure
characteristics."
In other words, the impact of hypertension on the aging brain may depend on the pattern of blood
pressure from midlife onward.
The authors of the current study, published in JAMA Network, took data from the
Atherosclerosis Risk in Communities study. This study included 4,761 participants whose
researchers evaluated six times across 24 years.
At the fifth and sixth visits, which were 4–5 years apart, participants underwent a neurocognitive
evaluation to test for dementia and cognitive decline. Between these two evaluations, doctors
diagnosed 516 new cases of dementia.
The authors summarize the focus of their study: The current study examined the association of
midlife to late-life blood pressure patterns with incident dementia, mild cognitive impairment,
and late-life cognitive change.
In their analysis, the researchers controlled for several variables, including age, sex, race, level of
education, tobacco smoking status, alcohol consumption, cholesterol levels, and more.
They found that individuals who had hypertension in midlife that continued into later life had a
A higher risk of dementia than individuals who maintained normal blood pressure.
Dementia risk also increased for individuals who had hypertension in midlife and low blood
pressure (hypotension) in later life; these individuals also had a higher risk of cognitive decline.
The authors summarize their findings:
A pattern of sustained hypertension from the middle to late life and a pattern of midlife
hypertension followed by late-life hypotension was associated with an increased risk for
subsequent dementia, compared with participants who maintained normal blood pressure."
This relationship was only significant in younger (under 74 years old) white participants. The
researchers did not find this association in the older group or in black participants.

These findings demonstrate the importance of viewing blood pressure patterns across a lifespan.
As the authors explain, "late-life hypertension and late-life hypotension were associated with
increased dementia risk, but only among individuals with hypertension during the middle
adulthood."
In other words, individuals who maintained healthy blood pressure throughout their midlife did
not have increased dementia risk if their blood pressure became too high or too low in later life.
The study used a large number of participants and took multiple measurements over an extended
period, but the authors do note certain limitations.
For instance, individuals with particularly high blood pressure and poorer cognition during
midlife was most likely to drop out, which could have affected the results.
Also, because the scientists did not see the same relationship in black participants, the findings
might not be relevant for other populations.
Although this study found significant associations between patterns of blood pressure throughout
life, they cannot define whether it is a causal relationship.
Earlier studies have shown that blood pressure tends to decline in the lead up to dementia.
However, it is not clear whether blood pressure somehow increases dementia risk, or whether
neurodegeneration impacts blood pressure.
As the authors explain, the possibility that early neurological changes may be responsible for
late-life declines in blood pressure cannot be ruled out."
Because hypertension is so prevalent, and dementia is a growing concern, research into the
relationship between the two is more important than ever. More work is sure to follow.