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Friday, 21st January 2005
Men who consume three or more alcoholic beverages per day are 45 percent more
likely to suffer a stroke compared with nondrinkers.
BOSTON -- A new study led by researchers at Beth Israel Deaconess
Medical Center (BIDMC) and the Harvard School of Public Health (HSPH)
has found that heavy drinkers -- men who consume an average of three or
more alcoholic beverages per day -- are nearly 45 percent more likely to
suffer an ischemic stroke compared with nondrinkers.
The study also
found that while light and moderate drinkers appear to be at neither
greater risk nor greater advantage than abstainers when it comes to
ischemic stroke, the frequency with which they consume alcohol may
modestly influence their risk.
The findings, reported in the January 4, 2005 issue of the Annals of
Internal Medicine, help shed light on a subject that has been the source
of some confusion, and reinforce the importance of what the authors call
"drinking patterns," the number of days per week that alcohol is
consumed and the amount consumed on drinking days.
"In this study, the participants who were at lowest risk for stroke
were the men who consumed one or two drinks on three to four days of the
week," says lead author Kenneth Mukamal, MD, MPH, a general internist at
BIDMC and Assistant Professor of Medicine at Harvard Medical School.
"The importance of drinking pattern for stroke risk parallels our
previous findings among this same group of men regarding alcohol
consumption and the risk of developing diabetes and coronary heart
disease. Among all three types of disease, the lowest risk seems to
occur when consumption is limited to one or, at most, two drinks,
approximately every other day, with little benefit shown above three to
four drinking days per week."
Nearly 700,000 individuals in the U.S. suffer an ischemic stroke each
year. Sometimes referred to as a "brain attack," the condition develops
when an artery in the brain becomes blocked by a blood clot. There are
two types of ischemic stroke: thrombotic, which results from the
development of a blood clot within the brain itself, and embolic, which
is the result of a clot traveling through the bloodstream from another
part of the body and becoming lodged in the brain. In both instances,
the ensuing deprivation of oxygen and nutrients to the brain can result
in neurological damage or death.
During the course of the 14-year study the authors followed 38,156
participants who are part of the HSPH-based Health Professionals
Follow-up Study. Beginning in 1986 and continuing every four years
thereafter until 2000, the male participants, who ranged in age from 40
to 75, responded to a detailed questionnaire regarding diet and medical
history, including alcohol consumption.
The researchers examined the following factors to gauge the influence
of alcohol consumption on the risk for ischemic stroke: average amount
of alcohol consumed; drinking patterns (number of days per week alcohol
was consumed); and type of beverage consumed (beer, red wine, white
wine, or spirits). They also looked at the incidence of both subtypes of
ischemic stroke ? thrombotic and embolic. During the course of the
study, they confirmed 412 cases of ischemic stroke among the study
Their findings showed that men whose average alcohol intake was three
or more drinks per day had a 42 percent higher risk of ischemic stroke
(particularly embolic stroke) than did abstainers. This finding, says
Mukamal, may be attributable to alcohol's association with both high
blood pressure and atrial fibrillation.
Although the findings also found that average intake of lower amounts
of alcohol was associated with neither a significantly higher nor lower
risk of stroke, when drinking frequency was taken into account, the
light and moderate drinkers who consumed alcohol three to four days per
week had a modest 32 percent lower stroke risk than did nondrinkers.
"I think there has been a subtle assumption that moderate drinking is
associated with a lower risk of ischemic stroke, similar to the way that
it is associated with a lower risk of heart attack," says Mukamal. "But
our study did not demonstrate a statistically significant role for
alcohol in guarding against stroke. While there does appear to be a
small window for which light drinking is associated with lower risk,
it's important to note that this window is smaller than it is for heart
disease and therefore you cannot simply extrapolate between the two."
Mukamal notes that red wine appeared to offer slightly more
protection than other types of alcohol, with red-wine drinkers shown to
be at 23 percent lower risk of ischemic stroke. (Intake of one or more
glasses per day was linked to a 46 percent lower risk, but few men in
this study drank red wine on a daily basis, he adds.)
"Compared with other types of alcohol, red wine was associated with a
step-wise lower risk of ischemic stroke," according to Mukamal. "This is
curious, because among this population of men, red wine is not linked to
a lower risk of heart disease any more than any other type of alcohol,
so it's unclear why this would be the case with stroke." He adds that
further research will be needed to help clarify this finding.
For now, the standard recommendation that men drink no more than two
drinks per drinking day still appears to be a good one, say the authors.
"Our findings directly support current public health recommendations
stating that men should consume less than two drinks per day," the
authors write. "At the same time, our findings support the safety of
continued light alcohol consumption among adults who have been able to
appropriately regulate the quality and timing of their alcohol use."
Study coauthors include senior author Eric Rimm, ScD, Walter Willett,
MD, DrPH, Alberto Ascherio, MD, DrPH, Ichiro Kawachi, MD, PhD, and Meir
Stampfer, MD, DrPH, of the Harvard School of Public Health; Murray
Mittleman, MD, DrPH, of Beth Israel Deaconess Medical Center; Katherine
Conigrave, MD, of Royal Prince Albert Hospital, Camperdown, Australia;
and Carlos Camargo Jr., MD, DrPH, of Massachusetts General Hospital.
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