June 26, 2008 -- It's possible to have a stroke and not realize it
immediately. So it's wise to know the signs. But what if a stroke occurred and
you didn't even notice?
A new study found that nearly 11% of people who thought they were healthy
actually had some brain damage from a "silent" stroke. Silent strokes are true
strokes but don't result in any noticeable symptoms. People who have had a
silent stroke are at higher risk for subsequent strokes and for an accelerated
loss of mental skills.
Researchers, led by Rohit Das, MD, from Boston University's School of
Medicine, reviewed MRI (magnetic resonance imaging) scans from 2,040 people
participating in the Framingham Study, an ongoing study examining the
relationship between risk factors and subsequent cardiovascular events. The MRI
scans were reviewed for evidence of stroke. The average age of the participants
was 62; most were of European ancestry. None of the participants had a history
of stroke or stroke-type symptoms.
The study also examined whether people who had silent strokes had more
concentrated levels of cholesterol in their blood and more extensive thickening
in the carotid arteries, the main arteries that supply the head and neck with
Here are the main results from routine MRI scans:
Nearly 11% of participants who showed no overt sign of stroke had suffered
some brain damage from a silent stroke.
People who had an irregular heartbeat, also known as atrial
fibrillation, were more likely to have had a silent stroke.
Having high blood
pressure (hypertension) was associated with a greater chance of having a
Elevated levels of the amino acid homocysteine in the blood "significantly"
increased participants' chances of having a silent stroke.
Researchers say people need to be aware of the risk factors for a silent
stroke, which are the same as for a full-blown stroke.