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Moderate Alcohol Shrinks
Brain of Middle-Aged Adults?
Earlier
study says it does same for senior citizens
DALLAS, Dec. 5, 2003
Consuming low to moderate amounts of alcohol may be linked to decreased
brain size in middle-aged adults, according to a new study published in
todays rapid access issue of
Stroke: Journal of the American Heart Association.
The new study also
showed that low to moderate alcohol intake did not lower their stroke
risk, as some previous studies found.
While chronic alcohol
abuse has been associated with brain volume loss, this study suggests
that even moderate alcohol intake may promote brain atrophy, said
Jingzhong Ding, Ph.D., lead author and a research associate at the
Bloomberg School of Public Health at Johns Hopkins University in
Baltimore. Brain atrophy may be associated with lower cognition and
reduced extremity function.
Many studies have shown
a strong correlation between heavy drinking and a higher risk of stroke
and brain deterioration; however, evidence about the effects of low to
moderate alcohol intake varies. Some studies have shown that alcohol
intake is associated with reduced stroke risk in certain age groups, and
others have found no correlation.
One study of people age
65 or older the
Cardiovascular Health Study found
that moderate alcohol intake was associated with fewer brain infarcts
(dead tissue) and white matter lesions in the brain. However, moderate
alcohol intake was also linked with brain atrophy (brain shrinkage).
Ding and colleagues
from five other institutions assessed the relationship of alcohol intake
with brain abnormalities in middle-aged adults. Cognitive decline is
more common in older adults and alcohol consumption may change with
aging. So, Ding felt that evaluating middle-aged adults could provide
new evidence.
They used magnetic
resonance imaging (MRI) to measure infarcts, changes in the inner matter
of the brain known as white matter lesions, and brain atrophy. Infarcts
and white matter lesions increase stroke risk.
The researchers
randomly selected 2,821 participants, 55 years or older, from Forsyth
County, N.C., and Jackson, Miss., who were participating in the
Atherosclerosis Risk in Communities (ARIC) Study, a prospective,
community-based investigation into the cause and natural development of
atherosclerosis. Researchers used baseline information collected
between 198789 and conducted follow-up examinations every three years
until 1995. Participants were asked to have a brain MRI examination
between 199395. After excluding those not eligible or those who
declined to participate, 1,909 middle-aged adults (22 percent white men,
18 percent black men, 29 percent white women and 32 percent black women)
underwent a brain MRI. Neuroradiologists then identified the presence
of infarction, the extent of white matter lesions, and ventricular and
sulcal size void areas of the brain containing only cerebrospinal
fluid.
Participants
self-reported alcohol consumption and were categorized into five groups:
never drinkers, former drinkers, occasional drinkers (less than one
drink per week), low drinkers (between one to six drinks per week), and
moderate drinkers (seven to 14 drinks per week). Data on income,
physical activity, cigarette smoking, cholesterol, hypertension, heart
disease, diabetes, and stroke were also recorded.
In general, they found
that as the level of alcohol intake increased, so did ventricular and
sulcal size.
There is no brain
tissue in the ventricular and sulcal areas, as these areas are filled
with cerebrospinal fluid, Ding said. Therefore, an increase in
ventricular and sulcal size indicates a reduction in the brain tissue,
or brain atrophy, around the ventricular and sulcal areas.
Researchers observed no
consistent association with infarction or white matter grade. Compared
with never drinkers, former drinkers and moderate drinkers had higher
odds of infarction without considering other factors. After adjusting
for influencing factors, there was no protection from infarction
associated with occasional or low drinking. There were also no
consistent differences in white matter between current drinkers and
never drinkers when looking at men and women and each racial group.
In general, both
ventricular and sulcal size increased with higher alcohol intake among
men, women, whites, and blacks, indicating a dose-response effect of
alcohol consumption and brain atrophy. This finding suggests that the
process might begin earlier in life than previously suggested.
However, the
researchers note that the clinical significance of the small reduction
of brain volume associated with moderate alcohol drinking is unknown.
Because MRI measures
in the brain were only conducted once during follow up, a causal
relationship between alcohol intake and brain atrophy is difficult to
establish, Ding said. Regardless of that limitation, he said, the
strength of the study lies in the large population-based sample and the
consistency of the findings by gender and race.
This study adds
further to our knowledge concerning the effects of alcohol on the brain
and provides new technology to investigate such issues, said Edgar J.
Kenton, III, M.D., a spokesperson for the American Stroke Association.
Co-authors are Marsha
L. Eigenbrodt, M.D.; Thomas H. Mosley, Jr., Ph.D.; Richard G.
Hutchinson, M.D.; Aaron R. Folsom, M.D.; Tamara B. Harris, M.D.; and F.
Javier Nieto, M.D., Ph.D. The study was partly funded by the National
Heart, Lung, and Blood Institute.
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