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 Researchers examined data from one month of daily home blood
pressure readings for 1,674 older adults without dementia. During
the next five years, compared to individuals with little to no
fluctuation, people with the most variations in blood pressure were
more than twice as likely to develop dementia.
“The present study demonstrated that an increased day-to-day blood
pressure variation (measured at home) was significantly associated
with the development of all-cause dementia, vascular dementia, and
Alzheimer’s disease, regardless of average home blood pressure,”
said lead study author Dr. Tomoyuki Ohara, of the Graduate School of
Medical Sciences at Kyushu University in Fukuoka City.
While the study didn’t assess why this might be the case, it’s
possible that daily variation in blood pressure might cause changes
in the brain’s structure and function that contribute to the
development of dementia, Ohara said by email.
Consistently high blood pressure, or hypertension, is a known risk
factor for dementia. Previous research has also shown a link between
cognitive impairment and dementia and different blood pressure
readings at the doctor’s office.
Home monitoring might give a more reliable snapshot of blood
pressure than tests at the doctor’s office because stress or anxiety
about these exams sometimes leads patients to have higher blood
pressure at the office than they do at home, a so-called “white
coat” effect.
Participants in the current study were 71 years old on average. For
one month, they typically measured their blood pressure three times
each morning before eating breakfast or taking medication. About 43
percent of them took drugs to manage high blood pressure.
Researchers reviewed data from blood pressure readings taken during
that month, conducted cognitive testing to uncover the development
of dementia, and reviewed medical records for the occurrence of
stroke.
Five years later, 134 participants had developed Alzheimer’s disease
and 47 had developed what’s known as vascular dementia, which
results from diminished blood flow to the brain and is often related
to the occurrence of small strokes.
People with the most variation in daily blood pressure readings at
the start of the study were more than twice as likely to develop
Alzheimer’s disease and almost three times more likely to develop
vascular dementia, researchers report in Circulation.
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Among participants with the most variability in blood pressure,
higher systolic blood pressure (the top number in a blood pressure
reading) in particular increased the risk of vascular dementia but
didn’t appear to heighten the odds of Alzheimer’s disease. Systolic
pressure is the pressure blood exerts against artery walls when the
heart beats.
One limitation of the study is that researchers lacked data on
changes in blood pressure after the initial home monitoring period
and didn’t have information on any lifestyle changes or medications
people may have used to control blood pressure during the five-year
follow-up period, the authors note.
It’s also possible that fluctuations in blood pressure could be a
symptom of cognitive decline in progress rather than a risk factor
for developing dementia in the future, Dr. Costantino Iadecola,
director of the Feil Family Brain and Mind Research Institute at
Weill Cornell Medicine in New York writes in an accompanying
editorial.
Iadecola noted that, presently, doctors don’t know how to reduce
variability in blood pressure.
“The key question to be answered is whether interventions to control
blood pressure variation, once available, would reduce dementia
risk,” he said by email.
“In the meantime, the take-home message is that the health of the
cardiovascular system is of paramount importance to the health of
the brain,” Iadecola added. “Even if specific measures to target
blood pressure variation may not be available at this time,
maintaining general cardiovascular health through lifestyle changes
(diet, exercise, etc.) and control of risk factors (diabetes,
hypertension, smoking, obesity, etc.) remain the most sensible
approaches to stave off dementia.”
SOURCE: http://bit.ly/2vIJlJv Circulation, online August 7, 2017.
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