Men who did not have good relationships with their siblings in childhood are more likely to develop major depression as adults, a new study shows.

In fact, the quality of sibling relationships was a stronger predictor of future depression risk than the relationship with parents, Dr. Robert J. Waldinger of Brigham and Women’s Hospital in Boston and colleagues found.

“We probably want to pay more attention to sibling relationships, not just to make life better for kids in the present but to think about it as something that might potentially have influence on their well-being in the future,” Waldinger told Reuters Health in an interview.

Childhood relationships with brothers and sisters are central to a person’s social and emotional development, but little is known about how these relationships affect future mental health, he and his colleagues report in the American Journal of Psychiatry.

To investigate, the researchers looked at 229 men who were followed from age 20 to age 50. At the study’s outset, interviewers rated the men’s relationships with their parents and siblings.

Twenty-six percent of the men who had very conflicted or distant relationships with their siblings had developed major depression by age 50. Ten percent with average sibling relationships and 3 percent with good sibling relationships also developed major depression.

There was no link between the quality of parent-child relationships and future depression risk, but people with a family history of depression were more likely to be depressed in adulthood.

The men with poor sibling relationships were also more likely to use mood-altering drugs such as tranquilizers, stimulants and sleeping pills later in life.

“It is possible that for some of these men, difficulty forming a strong positive bond with at least one sibling in childhood was an early marker of biological or psychological processes that would eventually result in adult depression,” Waldinger and his team write.

The good news about the findings, Waldinger noted, is that a good childhood relationship with just one sibling may shield a person from being depressed down the road. “The closeness with one sibling seems to be a good thing,” he said.

SOURCE: American Journal of Psychiatry, June 2007.