Alzheimer's, Dementia & Mental Health
Hypertension Predicts Dementia in Seniors Losing
Ability to Organize, Make Decisions
Control of high blood pressure in this senior
citizen group could cut in half the projected 50% five-year rate of
progression to dementia
Feb. 8, 2010 - High blood pressure appears to
predict the progression to dementia in senior citizens with impaired
executive functions (ability to organize thoughts and make decisions)
but not in those with memory dysfunction, according to a report in the
February issue of Archives of Neurology, one of the JAMA/Archives
journals.
"Although midlife hypertension has been confirmed
as a risk factor for the development of dementia in late life, there
have been conflicting findings about the role of late-life
hypertension," the authors write in explaining their pursuit of this
study.
Individuals with mild cognitive (thinking, learning
and memory) impairment - the state between aging-related brain changes
and fully developed dementia - may experience deficits in different
domains.
For instance, some have impairments only in memory
function and are more likely to develop Alzheimer's disease, whereas
those whose impairment follows a stroke or other vascular (blood
vessel-related) event often experience executive dysfunction.
"Because hypertension is a major risk factor for
vascular brain diseases and vascular cognitive impairment, we postulated
that the cognitive domain of dysfunction may be the crucial factor that
determines the association between hypertension and cognitive
deterioration," the authors write.
To test this hypothesis, Shahram Oveisgharan, M.D.,
of University of Western Ontario, Canada, and Isfahan University of
Medical Sciences, Isfahan, Iran, and Vladimir Hachinski, M.D., F.R.C.P.C.,
D.Sc.(Lond)., also of University of Western Ontario, studied 990 older
adults (average age 83) with cognitive impairment but no dementia.
Over a five-year follow-up period, dementia
developed at approximately the same rate among participants with and
without hypertension (59.5 percent of individuals with high blood
pressure vs. 64.2 percent of those without).
A similar pattern was observed among those with
memory dysfunction alone and with both memory and executive dysfunction.
However, among patients with executive dysfunction
only, presence of hypertension was associated with an increased risk of
developing dementia (57.7 percent of those with high blood pressure
progressed to dementia, vs. 28 percent of those without).
"This study may have profound implications for
community dwellers with cognitive impairment, no dementia," the authors
write.
"Worldwide, neurologic disorders are the most
frequent cause of disability-adjusted life years; among these,
cerebrovascular disease is the most common risk factor, and dementia is
the second most common. There is no preventive or therapeutic
intervention to mitigate this public health burden."
"We show herein that the presence of hypertension
predicts progression to dementia in a subgroup of about one-third of
subjects with cognitive impairment, no dementia," they conclude.
"Control of hypertension in this population could
decrease by one-half the projected 50-percent five-year rate of
progression to dementia."
This study was supported by a grant
from the Alzheimer Association.
