Depressive symptoms in problem drinkers often are the result of heavy alcohol intake, a new study suggests.

The 30-year study included nearly 400 men, about half of whom were at increased risk for drinking problems because their fathers were alcoholics, MedicalXpress reports. Over the course of the study, about 41 percent of the men with alcoholic fathers developed alcohol abuse or dependence. Almost 20 percent suffered at least one bout of major depression, the article notes.

Among men with alcohol problems, almost one-third of major depressive episodes appeared only when the men were drinking heavily. The study appears in the Journal of Studies on Alcohol and Drugs.

“I don’t know that the average person realizes that heavy drinking can induce mood problems,” lead researcher Marc A. Schuckit, MD, of the University of California, San Diego School of Medicine, said in a news release.

Dr. Schuckit noted that depression caused by heavy drinking is treated differently from major depressive episodes with other causes. He said the symptoms of depression caused by heavy drinking can be the same as those seen in people who are not heavy drinkers. However, if the symptoms develop in the context of heavy drinking, they are likely to disappear within several weeks to a month after the person stops drinking, and rarely requires antidepressants.

Doctors should consider alcohol use disorders as a potential cause of depression, Dr. Schuckit said. He found no evidence that people with a history of major depression were at increased risk for developing alcohol problems. “If you’re an alcoholic, you’re going to have a lot of mood problems,” he said. “And you may be tempted to say, ‘Well, I drink a lot because I’m depressed.’ You may be right, but it’s even more likely that you’re depressed because you drink heavily.”