Risk of depression (search) intensifies as it is passed down from generation to generation.

Having a parent with a history of depression is a known risk factor for depression in children and teens. Now compelling new research shows the risk to be far greater in children with both a parent and grandparent with depressive disorders.

Researchers from Columbia University Medical Center followed three generations of families for more than 20 years. They found that more than half of the children with a parent and a grandparent who suffered from depression were also diagnosed with a psychiatric disorder before they reached their teens.

“Children of parents and grandparents with depression are at extremely high risk for mood and anxiety disorders even when they’re very young,” says lead researcher Myrna Weissman, PhD. “They should be considered for treatment if they develop anxiety disorder, or at least monitored very closely.”

Double the Risk

The study by Weissman and colleagues is the first to assess depression in low- and high-risk families over three generations. Forty-seven adults were enrolled in 1982. Over the next two decades, 86 of their children and 161 of their grandchildren were also enrolled. The average age of the grandchildren in the study is now 12.

The frequency of anxiety disorders among children with both a parent and grandparent who suffered from depression was more than twice that which would be expected in the general population. Anxiety disorders are diagnosed more often than depression in children but are considered a strong risk factor for depression later in life.

The researchers found that 54 percent of children who had a grandparent and a parent with a history of depression had an anxiety disorder, compared with just 11 percent of low-risk children who had no family history of depression.

Sixty-eight percent of the children in the high-risk group had some type of psychiatric condition, compared with 21 percent of the children with no family risk. The findings were published in the January issue of the Archives of General Psychiatry.

Weissman and colleagues conclude that anxiety disorders in children with a two-generation history of family depression can be viewed “as an expression of the same underlying disorder” as the depression experienced by the parent and grandparent.

“It is important for anyone treating depressed adults to get family histories and also to find out what is going on with their children,” Weissman tells WebMD.

Nature vs. Nurture

Weissman and her Columbia University colleagues are collecting brain imaging data on the families involved in the study in an effort to better understand the factors that influence family risk. They are also conducting research to determine if treating parental depression prevents or delays the onset of depression and other psychiatric disorders in children.

“These are probably genetic illnesses, but they are environmentally influenced,” she says. “If you can reduce the stress of exposure to the parent’s depression you may delay the onset of the child’s illness, which can have a big impact on development.”

Washington, D.C., psychiatrist Carol Kleinman, MD, tells WebMD that the research reinforces the importance of knowing a patient’s family history of depression and other psychiatric disorders.

“It is something that we are very aware of,” she says. “Certainly genetics plays a role here, but so does environment. Families with a depressed parent tend to be very isolated.”

Child and adolescent psychiatrist Stephanie Hamarman, MD, says obtaining a careful family history is especially important when treating children and teens with depression and other psychiatric problems. Hamarman is chief of psychiatry at Brooklyn’s Stanley S. Lamm Institute.

She says parents with a history of depression tend to be aware that their children are also at risk.

“I have been seeing more and more concerned moms who have been struggling with depression themselves who bring their kids in because they do know it is important.”

By Salynn Boyles, reviewed by Michael W. Smith, MD

SOURCES: Weissman, M. Archives of General Psychiatry, January 2005; vol 62: pp 29-36. Myrna Weissman, PhD, professor of psychiatry and epidemiology, Columbia University Medical Center; chief, division of clinical and genetic epidemiology, New York State Psychiatric Institute. Stephanie Hamarman, MD, chief of psychiatry, Stanley S. Lamm Institute, Brooklyn, N.Y. Carol Kleinman, MD, assistant clinical professor of psychiatry, George Washington University Medical School, Washington, D.C.