March 6 (HealthDay News) -- Alcohol abuse may increase the risk of depression, instead of the other way around, a New Zealand study suggests.
Previous research has identified a link between alcohol abuse or dependence and major depression. But it hasn't been determined whether one disorder causes the other, or whether a common genetic or environmental factor increases the risk for both conditions.
This new study included 1,055 people born in 1977 who were assessed for alcohol abuse and depression at ages 17 to 18, 20 to 21, and 24 to 25. The number of participants who met criteria for alcohol problems and major depression were: 19.4 percent and 18.2 percent, respectively, at ages 17 to 18; 22.4 percent and 18.2 percent at ages 20 to 21; and 13.6 percent and 13.8 percent at ages 24 to 25.
At all ages, alcohol abuse or dependence was associated with a 1.9 times increased risk of major depression, said David M. Ferguson and colleagues at the Christchurch School of Medicine and Health Sciences.
"This analysis suggested that the best-fitting model was one in which there was a unidirectional association from alcohol abuse or dependence to major depression but no reverse effect from major depression to alcohol abuse or dependence," they wrote.
"The underlying mechanisms that give rise to such an association are unclear; however, it has been proposed that this link may arise from genetic processes in which the use of alcohol acts to trigger genetic markers that increase the risk of major depression. In addition, further research suggests that alcohol's depressant characteristics may lead to periods of depressed affect among those with alcohol abuse or dependence."
In addition, alcohol abuse may cause social, financial and legal problems that cause stress and increase the risk of depression, said the researchers, who added that further research is required to fully understand the connection between alcohol abuse and depression.
The study was published in the March issue of the Archives of General Psychiatry.
The U.S. National Institute of Mental Health has more about depression.
SOURCE: JAMA/Archives journals, news release, March 2, 2009