If you think a mug of fortified eggnog is going to protect you from strokes, pour it back in the punchbowl. A new study finds that alcohol does not guard against strokes.
Moderate alcohol intake--one to two drinks per day--appears to protect people from heart disease. Because strokes are similar to heart attacks in that a blood vessel clogs and starves tissue of oxygen, researchers have speculated that alcohol might protect against strokes as well. But previous studies have turned up mixed results.
Hoping to settle the debate, epidemiologist Jingzhong Ding of Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland, and colleagues examined data from the Atherosclerosis Risk in Communities Study, a project that performed magnetic resonance imaging (MRIs) in the mid-1990s on 1909 middle-aged adults in the southern United States. The researchers scaled the volunteers on how much alcohol they reported consuming--from teetotalers to moderate drinkers who consumed about 14 drinks per week--and then looked at their MRI scans for signs of dead or dying brain tissue, known risk factors for stroke. The researchers also noted brain volume.
Alcohol intake did not reduce the incidence of dead tissue and therefore presumably didn't reduce the risk of stroke, the team reports in the 7 January 2004 issue of Stroke. However, even small amounts of libations correlated with reduced brain volume, an indication of atrophy. On the nine-point scale researchers use to rate brain atrophy, all subjects in this study ranged between 2 and 3. (Severe alcoholics generally range from 4 to 6. More severe atrophy can cause cognitive impairments or even dementia.) For light to moderate drinkers, the researchers calculated that with each daily drink of alcohol, the atrophy worsened by about 0.01 on the scale. Ding emphasizes that the study only shows a correlation. "We cannot establish that alcohol causes brain atrophy, but [the work] does suggest that." The results also suggest that the atrophy occurs earlier in life than previously thought, he says.
Epidemiologist Kenneth Mukamal of Harvard Medical School in Boston says that some of the shrinkage may be due to alcohol drying the brain out, which is a reversible contributor to hangovers. However, he adds, some of it is probably due to brain atrophy as well, which is not reversible. The study "isn't a reason for people to change their drinking habits one way or the other," he says. "But they should realize [that drinking alcohol] is potentially deleterious."
Jingzhong Ding's Web page