Dementia Seen in More Than 25% of Stroke Survivors
March 15, 2000 (Atlanta) -- One of every four stroke survivors develops
dementia, according to research reported in the March 14 issue of the journal
Neurology. The study is the first to include a large number of non-white
people -- and in perhaps its most provocative finding it suggests that the risk
of dementia after stroke is up to three times higher for black and Hispanic
patients than for white patients.
A stroke is a sudden loss of brain function usually caused by a blocked
blood vessel that causes loss of oxygen in a particular part of the brain.
There may be sudden loss of vision, strength, balance, coordination, speech, or
the ability to understand speech. Symptoms such as vomiting, nausea, hiccups,
or difficulty swallowing may occur, and there can be severe headache followed
by loss of consciousness.
Dementia is a loss of mental function that may include loss of memory and/or
judgement, often with changes in personality.
A person's education also played a major role in determining whether
dementia followed stroke, according to the study. Compared to stroke patients
with 13 or more years of education, those who had only eight years of schooling
had four times the risk of dementia. Those with nine to 12 years of school had
three times the risk.
"It's always important to think of the public health implications of
studies like this," lead author David W. Desmond, PhD, tells WebMD. "It
shows that there are certain groups that are at increased risk, and attention
needs to be given to these groups to find out why. Ours is the largest study of
stroke and dementia ever published. It is not just large but has a high
proportion of black and Hispanic patients, and this allows us to identify the
risks that they face."
New studies to investigate the basis for these risks already are being
planned, says John R. Marler, MD, associate director for clinical trials at the
National Institute for Neurological Disorders and Stroke (NINDS), which funded
the current study.
"It's a very complex question that a number of studies have looked at
and none of them have sorted it out," Marler tells WebMD. "It seems
that a lot of the risk factors for stroke are heightened in nonwhites as well
-- hypertension, high cholesterol, smoking -- but these risk factors alone
don't entirely explain the risk. Is some component cultural or based on some
[physical] difference between groups? We haven't been able to sort that out
yet. ... There are all sorts of opinions, but there are no scientific answers
Desmond, assistant professor of pathology and neurology at SUNY Downstate
Medical Center in Brooklyn, says that his study may actually have
underestimated the number of patients who develop dementia after stroke. One
reason is that the study used a conservative definition of dementia. Another
reason is that because dementia indicates that the person suffered a more
severe stroke, many patients with dementia died before they could be