Alcohol abuse can wreak havoc on a relationship, and could ultimately lead to divorce, but according to a recent study funded by the National Institute on Alcohol Abuse and Alcoholism, a marriage is more likely to dissolve if only one spouse is a heavy drinker, as opposed to both. Researchers from the University at Buffalo Research Institute on Addictions (RIA) determined that married couples that drink heavily are just as likely to stay together as married couples that don't drink.

“This research provides solid evidence to bolster the commonplace notion that heavy drinking by one partner can lead to divorce,” Kenneth Leonard, Ph.D, RIA director and lead author of the study, said in a statement. “Although some people might think that’s a likely outcome, there was surprisingly little data to back up that claim until now.”

Dr. Leonard and colleagues followed 634 couples over a nine-year period that began when they got married. “Heavy drinkers” consumed six or more drinks at one time, or drank until they were intoxicated. The research team included factors that could also contribute to marital dissatisfaction, such as depression, socioeconomic status, tobacco, and marijuana use.

Both heavy-drinking couples and nondrinking couples yielded about a 30 percent divorce rate. Marriages in which only one spouse drank heavily — having six or more drinks or drinking until intoxicated — ended in divorce 50 percent of the time. Researchers also noticed a higher rate of divorce in marriages with a heavy-drinking wife, but warned that there wasn't enough data to call it a significant find.

“Our results indicate that it is the difference between the couple’s drinking habits, rather than the drinking itself, that leads to marital dissatisfaction, separation, and divorce,” Dr. Leonard explained in the statement. “Heavy drinking spouses may be more tolerant of negative experiences related to alcohol due to their own drinking habits.”

Although the research team set out to establish the influence heavy drinking has on spousal satisfaction within marriage, the effect heavy drinking has on children was not studied. According to the National Council on Alcoholism and Drug Dependence, 26.8 million children in the United States are exposed to alcoholism by their family, resulting in a higher risk of the child becoming an alcoholic.

“Ultimately, we hope our findings will be helpful to marriage therapists and mental health practitioners who can explore whether a difference in drinking habits is causing conflicts between couples seeking help,” Dr. Leonard said in the statement. “While two heavy drinkers may not divorce, they may create a particularly bad climate for their children.”

Hormish G, Smith P, Leonard K. Heavy drinking is bad for marriage if 1 spouse drinks, but not both. Psychology of Addictive Behaviors. 2013.