Men and women at risk for alcohol dependence are more likely to choose a mate who also is at risk, School of Medicine investigators found. But that doesn’t necessarily mean that both spouses will be problem drinkers.
Alcoholism is more common among partners of alcoholics than among partners of non-alcoholics, but not as common as it might be. The researchers found that in some cases, one spouse’s excesses with alcohol actually could help protect the other from alcohol dependence.
A team of researchers from the University and from the Queensland Institute of Medical Research in Brisbane, Australia, studied 5,974 twins born between 1902 and 1964 who were part of the Australian Twin Register. They also spoke with 3,814 of those twins’ spouses for the study, published in the May issue of the journal Alcoholism: Clinical & Experimental Research.
“As they say, ‘like marries like,'” said first author Julia D. Grant, Ph.D., research assistant professor of psychiatry. “Spouse selection is not a random process, and we call this non-random mating. People tend to choose mates who are similar to them, not only from the same neighborhood or socio-economic background, but also alike in personality and other behaviors. We found that people at risk for alcohol dependence tend to marry others who are at risk.”
Alcohol dependence is influenced by both genetic and environmental factors. Genetic influences explain about half of the variance in a person’s total risk for alcohol dependence, while the other half of an individual’s risk comes from environmental factors, such as employment, interests, friends and family.
“There’s a lot of room for different factors to influence the behavior of two people who are married,” Grant said. “One spouse could work at a place where co-workers go out for a drink after work. Or one spouse could be a regular churchgoer, while the other prefers to sleep.”
Another aspect of environment is the drinking behavior of one’s partner. The researchers found that the impact of the partner’s drinking depends on whether it’s examined along with non-random mating.
Once the researchers accounted statistically for the fact that “like marries like,” they saw that the additional influence of the partner’s behavior tended to reduce the likelihood of problem drinking. Grant said that although non-random mating means that a person with genetic risks for alcohol problems will tend to marry another with a propensity toward alcohol dependence, it appears that when one spouse begins to abuse alcohol, the other might actually reduce alcohol intake.
Grant plans to study how spouses might influence each other’s risk of alcohol dependence as well as other psychiatric disorders, such as depression, and how those factors interact.
“Education is a key to reducing risk for alcohol dependence,” she said. “Regardless of genetic risks, there are other detrimental environmental factors associated with alcohol, including reduced educational attainment and income, fewer social and neighborhood support networks, higher rates of divorce and single parenthood and exposure to other psychiatric problems. We need to make people aware of all of their risks so they can take steps to protect themselves.”