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HIGH BLOOD PRESSURE ASSOCIATED WITH RISK FOR MILD COGNITIVE IMPAIRMENT
December 10, 2007
CHICAGO—High blood pressure appears to be associated with an increased risk for
mild cognitive impairment, a condition that involves difficulties with thinking
and learning, according to a report in the December issue of Archives of
Neurology, one of the JAMA/Archives journals.
“Mild cognitive impairment has attracted increasing interest during the past
years, particularly as a means of identifying the early stages of Alzheimer’s
disease as a target for treatment and prevention,” the authors write as
background information in the article. About 9.9 of every 1,000 elderly
individuals without dementia develop mild cognitive impairment yearly. Of those,
10 percent to 12 percent progress to Alzheimer’s disease each year, compared
with 1 percent to 2 percent of the general population.
Christiane Reitz, M.D., Ph.D., and colleagues at the Columbia University Medical
Center, New York, followed 918 Medicare recipients age 65 and older (average age
76.3) without mild cognitive impairment beginning in 1992 through 1994. All
participants underwent an initial interview and physical examination, along with
tests of cognitive function, and then were examined again approximately every 18
months for an average of 4.7 years. Individuals with mild cognitive impairment
had low cognitive scores and a memory complaint, but could still perform daily
activities and did not receive a dementia diagnosis.
Over the follow-up period, 334 individuals developed mild cognitive impairment.
This included 160 cases of amnestic mild cognitive impairment, which involves
low scores on memory portions of the neuropsychological tests, and 174 cases of
non-amnestic mild cognitive impairment. Hypertension (high blood pressure) was
associated with an increased risk of all types of mild cognitive impairment that
was mostly driven by an increased risk of non-amnestic mild cognitive
impairment; hypertension was not associated with amnestic mild cognitive
impairment, nor with the change over time in memory and language abilities.
“The mechanisms by which blood pressure affects the risk of cognitive impairment
or dementia remain unclear,” the authors write. “Hypertension may cause
cognitive impairment through cerebrovascular disease. Hypertension is a risk
factor for subcortical white matter lesions found commonly in Alzheimer’s
disease. Hypertension may also contribute to a blood-brain barrier dysfunction,
which has been suggested to be involved in the cause of Alzheimer’s disease.
Other possible explanations for the association are shared risk factors,”
including the formation of cell-damaging compounds known as free radicals.
“Our findings support the hypothesis that hypertension increases the risk of
incident mild cognitive impairment, especially non-amnestic mild cognitive
impairment,” the authors conclude. “Preventing and treating hypertension may
have an important impact in lowering the risk of cognitive impairment.”
(Arch Neurol. 2007;64(12):1734-1740. Available to the media pre-embargo at
www.jamamedia.org).
Editor's Note: This study was supported by grants from the National Institutes
of Health; the Charles S. Robertson Memorial Gift for Research in Alzheimer’s
Disease; and the Blanchette Hooker Rockefeller Foundation. Please see the
article for additional information, including other authors, author
contributions and affiliations, financial disclosures, funding and support, etc.
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