Women are more vulnerable than men to many of the medical consequences of alcohol use. Although research has shown that male alcoholics generally have smaller brain volumes than nonalcoholic males, the few studies that have compared brain structure in alcoholic men and women have had mixed results. To adequately compare brain damage between alcoholic women and men, it is necessary to control for age and to have separate control groups of nonalcoholic men and women. Although the majority of studies suggest that women are more vulnerable to alcohol-induced brain damage than men, the evidence remains inconclusive. KEY WORDS: AODR (alcohol and other drug related) structural brain damage; AOD sensitivity; gender differences; AODR biological markers; cerebrospinal fluid; hippocampus; corpus callosum; cerebral cortex; brain imaging
Men and women are affected differently by many diseases, including alcohol-related conditions. For at least a quarter century researchers have recognized that many of the medical consequences of excessive alcohol consumption develop more rapidly among women than among men (Ashley et al. 1977). For example, alcoholic women develop cirrhosis (Loft et al. 1987), alcohol-induced weakening of the heart muscle (i.e., cardiomyopathy) (Fernandez-Sola et al. 1997), and nerve damage in the body's extremities (i.e., peripheral neuropathy) (Ammendola et al. 2000) after fewer years of heavy drinking than alcoholic men. Studies comparing men's and women's sensitivity to alcohol-induced brain damage, however, have yielded inconsistent results. This article reviews the research and the factors other than alcoholism that can affect gender-based comparisons of brain structure.
MALE AND FEMALE VULNERABILITY TO ALCOHOL-INDUCED BRAIN DAMAGE
As reviewed in this issue of Alcohol Research & Health (see the article by Rosenbloom and colleagues), many studies have found small but usually statistically significant differences in the brain volumes of male alcoholics compared with those of nonalcoholics. In contrast, few studies have directly compared brain structure between alcoholic men and alcoholic women. Two early computerized tomography studies (Jacobson 1986; Mann et al. 1992) compared brain shrinkage, a common marker of brain damage, in alcoholic men and women by measuring the increase in the fluid surrounding the brain (i.e., cerebrospinal fluid [CSF]), which is an indication of the size of the lateral ventricle (a CSF-filled cavity inside the brain that increases in size as the brain shrinks).
Both studies reported that male and female alcoholics had significantly larger amounts of intracranial CSF than control subjects did, indicating greater brain shrinkage among alcoholics of both genders; alcoholic women also reported about half as many years of excessive drinking as the alcoholic men. In addition to this evidence for excessive brain shrinkage among alcoholic women, there is also evidence that the degree of cognitive dysfunction in alcoholic women is similar to that in alcoholic men despite fewer years of heavy drinking on the part of the women (Nixon et al. 1995). These results suggested that the central nervous system (CNS) in women, like other organ systems, is more vulnerable to alcohol-induced damage than the CNS in men.
Subsequent studies have not universally confirmed women's greater vulnerability to alcohol-induced brain damage. For example, Kroft and colleagues (1991), using magnetic resonance imaging (MRI), failed to detect that the fluid-filled chambers in the brain (i.e., cerebral ventricles) were larger in alcoholic women than nonalcoholic women, although other researchers have found MRI evidence for ventricular enlargement among alcoholic men (Pfefferbaum et al. 1993). Two recent reports that appeared side by side in the American Journal of Psychiatry contradicted each other on the question of gender-related vulnerability to brain shrinkage in alcoholism (Hommer et al. …