Alcohol abuse does its neurological damage more quickly in women than in men, new research suggests. The finding adds to a growing body of evidence that is prompting researchers to consider whether the time is ripe for single-gender treatment programs for alcohol-dependent women and men.

Over the past few decades scientists have observed a narrowing of the gender gap in alcohol dependence. In the 1980s the ratio of male to female alcohol dependence stood at roughly five males for every female, according to figures compiled by Shelly Greenfield, a professor of psychiatry at Harvard Medical School. By 2002 the "dependence difference" had dropped to about 2.5 men for every woman. But although the gender gap in dependence may be closing, differences in the ways men and women respond to alcohol are emerging. Writing in the January 2012 issue of Alcoholism: Clinical and Experimental Research, principal investigator Claudia Fahlke from the Department of Psychology at the University of Gothenburg in Sweden and her colleagues found that alcohol's ability to reduce serotonin neurotransmission, was "telescoped" in alcoholic women compared with their male counterparts. In other words, although the alcohol-dependent men and women in the study differed substantially in their mean duration of excessive drinking—four years for the women and 14 years for the men—both sexes showed similar patterns of reduced serotonin activity compared with controls. The researchers gauged serotonergic neurotransmission by measuring its response to citalopram, a drug that stalls serotonin molecules in the synaptic gap (as measured by the hormone prolactin's response to citalopram. This pattern of reduced serotonergic neurotransmission matters, because some of the alcohol-induced abnormalities were found in brain regions involved in judgment, self-control and emotional regulation.

Carla A. Green of the Kaiser Permanente Northwest Center for Health Research says the serotonin results were "consistent with findings of more severe physical consequences of alcohol consumption among women compared to men." Green, who is also associate professor of public health and prevention medicine and of psychiatry at Oregon Health & Science University, points out that women with addictions are more likely to suffer from associated mental health conditions. "Given the link between serotonin and depression, and the links between alcohol dependence and depression, this finding suggests one pathway in which alcohol dependence may lead to depression, and do so more quickly among women," she says.

Previous work on gender differences in alcohol dependence has shown that women get drunk on fewer drinks than men owing to a deficit of alcohol dehydrogenase, the enzyme in the stomach lining that breaks down booze. After two beers, women are more likely than men to exceed legal levels of alcohol in the bloodstream. (Women also develop cirrhosis of the liver more rapidly.) Research aimed specifically at the treatment needs of alcoholic women has long been spotty, however. To that end, a recent pilot study conducted by Greenfield demonstrated that a woman-centered approach could be as effective as a mixed-gender control group over the course of a 12-week study. More importantly, follow-ups at six months showed that women from the all-female recovery groups relapsed less often than women in the mixed group. In her all-female treatment groups, Greenfield discovered that women shared personal information more readily, and bonding behavior was more noticeable, particularly for less assertive women. Greenfield now has a larger group study in progress—all part of a recent explosion of research on women and alcohol.

Green, who collaborated with Greenfield on an earlier review of gender research at the National Institute on Drug Abuse, says that "the most consistent, and, I'd argue, the most important finding in the literature is that it takes longer for women to enter treatment for similar severity of alcohol problems than it does for men." In general, women require medical treatment four years earlier than male problem drinkers, Greenfield suggests. In another study, Greenfield found that women tend to go to primary health care physicians rather than to specialty substance abuse programs for treatment, putting additional pressure on family doctors to diagnose and treat alcohol dependence in women as early as possible.

So, should it be all-female treatment, all of the time? No, Green says. Men and women respond similarly to many forms of treatment, including the use of naltrexone and other medications for alcoholism. But even at this stage in the work, Green says she thinks it is possible to pinpoint "particular groups of women for whom gender-specific treatment is more appropriate and needed." These groups include pregnant women, women who have been abused by men, and women with eating disorders. In such cases, "women-only programs are more likely to provide a greater range of services than mixed-gender programs," she says.

Sociocultural factors, as well as innate biochemistry, account for many of the problems women face in treatment. Deni Carise, chief clinical officer for the nonprofit treatment center Phoenix House in New York City and an adjunct professor of psychiatry at the University of Pennsylvania in Philadelphia, notes that women are also far more likely to have suffered emotional, physical or sexual trauma, and to have additional parenting and child-care responsibilities. For these women, Carise says, "it’s not about substance abuse differences." Suicide, depression and anxiety are all more common in women, Carise points out, and in many cases, those are the gender differences that matter.