FRIDAY, June 1, 2007 (HealthDay News) -- Men who don't get along with a sibling might be at higher risk for depression, new research shows.
"Among a group of men studied since their late teens, those who said they didn't have a close relationship with even one of their siblings were more likely to be depressed by the time they were 50," said study author Dr. Robert Waldinger, director of the Study of Adult Development at Brigham and Women's Hospital, in Boston.
"Having a close relationship with even one of your siblings made you less likely to be depressed," Waldinger added.
His team published the report in the June 1 issue of the American Journal of Psychiatry.
In the study, Waldinger and his colleagues collected data on 229 men from the time they were teens until they were in their 50s. The researchers looked at the men's quality of life and their relationships with their siblings, the quality of parenting they had, and any family history of depression.
The study has lasted for 68 years and is one of the longest studies of adult psychosocial development ever done, Waldinger noted.
His group found that the two things that predicted depression at 50 were poor relationships with brothers and sisters during childhood and a family history of depression.
The researchers aren't clear about what their finding means. "It could be that not being close to a sibling is an early harbinger of later depression," Waldinger said. "Or it could be that being close to a sibling helps you develop you skills dealing with peers."
"There is this connection," Waldinger said. "But we are not sure why."
One expert said the study provides valuable new insight into the origins of mental illness.
"This long-term study allows a unique opportunity to examine the relationship between early life development and long-term risk for common mental health and substance use problems," said Dr. Gregory Simon, a psychiatrist and mental health researcher at the Group Health Cooperative, in Seattle.
While this study suggests a strong relationship between childhood sibling relationships and adult depression, direction of that relationship can't be determined, Simon said.
"It is certainly possible that poor relationships with siblings during childhood have significant and enduring negative effects on mental health," Simon said. "It is also possible, however, that poor relationships with siblings are one of the early signs of depressive illness."
For more information on depression, visit the U.S. National Institute on Mental Health.