Sober reassessment:  Katy Perry and Russell Brand were locked in tonsil hockey combat at  the 2011 Grammys, but booze may have driven them apart since then.

Sober reassessment: Katy Perry and Russell Brand were locked in tonsil hockey combat at the 2011 Grammys, but booze may have driven them apart since then. Photo: Jason Merritt

Excessive alcohol use is often cited as a factor during a divorce or break-up, but a new study suggests that booze itself might not be to blame but rather the disparate drinking patterns of the couple. Research by Kenneth E. Leonard, and study co-authors Gregory Homish and Philip Smith, of University at Buffalo's Research Institute on Addictions, discovered that divorce rates spiked in relationships when one spouse was a heavy drinker, yet those where both partners enjoyed a tipple were just as likely to stay together as couples who don't drink at all.

The clinical psychologists followed 634 couples for the nine years following their weddings and implemented controls for factors “such as marijuana and tobacco use, depression and socioeconomic status, which can also be related to marital dissatisfaction, separation and divorce.” They found that almost 50 per cent of the marriages ended in divorce when only one partner drank more heavily - heavy drinking being defined as having six or more drinks in one sitting and/or drinking to intoxication - whereas divorce rates for all other couples sat at 30 per cent.

“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," said Leonard. “This research provides solid evidence to bolster the commonplace notion that heavy drinking by one partner can lead to divorce. Although some people might think that's a likely outcome, there was surprisingly little data to back up that claim until now.”

One high-profile example is that of Katy Perry and Russell Brand. Towards the tail-end of their marriage tabloids charged that recovered substance abuser Brand was finding it increasingly hard to tolerate the Last Fri-day Night singer's more intimate relationship with alcohol. Though of course no one but the two of them knows what really occurred, Brand did offer a clue during an interview with 60 Minutes last year.

“If you sort of sense there's an incompatibility then, in any relationship regardless of the status of the individual, it kind of is best to go separate ways,” he said of their marriage. “I think if you're someone who's really into mountain biking, it would be good to go out with someone else who's into mountain biking, and if you're really into Eastern mysticism, go out with someone else who into Eastern mysticism. I think if you're a devoted tennis professional and you get married to a crystal meth addict, you might have trouble … I've been in a lot of trouble.”

The researchers admitted to being surprised that partnerships involving two heavy drinkers seemed to face no more substantial marital issues than sober couples. But they warned it's not all fun and games following that second bottle of Bordeaux and that it could have broader impacts on the family unit.

“Heavy drinking spouses may be more tolerant of negative experiences related to alcohol due to their own drinking habits," said Leonard. “While two heavy drinkers may not divorce, they may create a particularly bad climate for their children.”

More surprising still was that they found divorce rates were at their highest when the wife was the heavier drinker. Though this is based on only a few couples and not yet statistically significant, Leonard says more research is needed in order to test his theory that problems arise when women drink more heavily due to conflict surrounding traditional gender roles. Ultimately, he hopes the data they collect will be used as a tool by mental health professionals to help treat couples in crisis.

“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,” he said.