"It appears that there is a strong connection between closeness to at least one sibling during childhood and having a lower risk of depression in adulthood," said lead author Robert Waldinger, M.D., director of the Study of Adult Development at BWH. The Study has lasted for 68 years and is one of the longest longitudinal studies of adult psychosocial development ever conducted.

Beginning in their late teens, 229 men were evaluated for the quality of their childhood relationships with siblings, the quality of parenting they received, family history of depression and the occurrence by age 50 of major depression.  Researchers found that even after taking into account the quality of relationship with parents, both poorer relationships with siblings during childhood and a family history of depression independently predicted both the occurrence of major depression and the frequency of use of mood-altering drugs by age 50.

"We don't understand at this time why close childhood sibling relationships may be connected with reduced risk of major depression during adulthood, but our data indicate an association and more research should be done to better understand this link," concludes Waldinger, who is also an associate professor of Psychiatry at Harvard Medical School.

This research is published in the June 1, 2007 issue of the American Journal of Psychiatry. It was funded by the National Institute of Mental Health.