NEW ORLEANS – Depression appears to reverse the anti-inflammatory effect of light to moderate alcohol consumption in men but not in women.
"The findings in men and women are very different. These are relatively novel findings and, honestly, I was surprised by the significant differences and the pattern of the differences. I wasn’t prepared to see this kind of a pattern," Edward C. Suarez, Ph.D., said at the annual meeting of the Society of Behavioral Medicine.
He presented the results of a cross-sectional study that examined the relationship between alcohol, depression, and C-reactive protein (CRP) in 229 adults with a mean age of 29 years and a body mass index of 25.2 kg/m2. A total of 22% of subjects had mild, moderate, or significant symptoms of depression based upon their Beck Depression Inventory scores. None of the participants was a problem drinker. Indeed, 25% were nondrinkers, 32% drank alcohol infrequently, and 43% were light to moderate drinkers, meaning they consumed anywhere from three drinks per week to two drinks per day.
In both men and women, mean CRP levels were highest in former or never drinkers and lowest in light to moderate drinkers, as has consistently been found in other epidemiologic studies. The mechanism involved in alcohol’s CRP-lowering effect is unclear, but the antioxidant properties of the polyphenols in alcohol are one good possibility. What’s new in this study is the finding that depressed men who were light to moderate drinkers had a mean CRP level fully 2.5 times greater than did nondepressed men who consumed similar quantities of alcohol, according to Dr. Suarez of Duke University in Durham, N.C.
Men who were teetotalers or infrequent drinkers had similar mean CRP levels, regardless of whether they were depressed.
In contrast, mean CRP levels in depressed women who were nondrinkers were threefold higher than in nondepressed nondrinking women. Unlike the men, however, there was no significant difference in mean CRP levels between depressed and nondepressed women who were light to moderate drinkers, nor in infrequent drinkers, the psychologist continued.
All of these results held true after adjustment for age, race, blood pressure, HDL level, and physical activity. This multivariate adjustment was carried out because the nondrinkers were significantly older and heavier than the drinkers.
Because Dr. Suarez hadn’t anticipated the finding that gender differences moderated the relationship between alcohol consumption, depression, and CRP, he went looking for confirmatory data from other studies to make sure he was onto something. He found it, after a fashion, in other investigators’ earlier analysis of the U.S. National Alcohol Survey, an epidemiologic study involving 5,777 men and women featuring 11 years of follow-up for all-cause mortality, which occurred in 540 subjects (Addiction 2002:97:29-38).
This earlier study showed the same gender-based pattern that Dr. Suarez found. For men, the highest relative risk of death was in heavy drinkers who were depressed. For women, the highest risk was in former drinkers who were depressed.
The National Alcohol Survey, however, didn’t collect CRP data, but a high CRP is evidence of a systemic inflammatory state that has been linked to increased mortality from cardiovascular disease, stroke, and other causes, so the increased CRP levels seen in currently depressed subjects in his own study could have long-term adverse consequences in terms of mortality risk, he said.
Dr. Suarez reported having no financial conflicts. His study was sponsored by the National Institutes of Health.