Teens who were depressed as children are far more likely than their peers to be obese, smoke cigarettes and lead sedentary lives, even if they no longer suffer from depression.
The research, by scientists at Washington University School of Medicine in St. Louis and the University of Pittsburgh, suggests that depression, even in children, can increase the risk of heart problems later in life.
The researchers report their findings March 15 at the annual meeting of the American Psychosomatic Society in Miami, Fla.
"Part of the reason this is so worrisome is that a number of recent studies have shown that when adolescents have these cardiac risk factors, they're much more likely to develop heart disease as adults and even to have a shorter lifespan," says first author Robert M. Carney, PhD, a professor of psychiatry at Washington University. "Active smokers as adolescents are twice as likely to die by the age of 55 than nonsmokers, and we see similar risks with obesity, so finding this link between childhood depression and these risk factors suggests that we need to very closely monitor young people who have been depressed."
Researchers have known for years that adults with depression are likely to have heart attacks and other cardiac problems, but it hasn't been clear when risk factors for heart disease such as smoking, obesity and sedentary lifestyle join forces with depression to increase the risk for heart problems.
"We know that depression in adults is associated with heart disease and a higher risk of dying from a heart attack or having serious complications," Carney says. "What we didn't know is at what stage of life we would begin to see evidence of this association between depression and these cardiac risk factors."
The researchers studied children who had participated in a 2004 study of the genetics of depression. At the time, their average age was 9. The investigators surveyed 201 children with a history of clinical depression, along with 195 of their siblings who never had been depressed. They also gathered information from 161 unrelated age- and gender-matched children with no history of depression.
In 2011, when the study participants had reached the age of 16, the researchers surveyed them again, looking at rates of smoking, obesity and physical activity in all three groups of adolescents.
"Of the kids who were depressed at age 9, 22 percent were obese at age 16," Carney says. "Only 17 percent of their siblings were obese, and the obesity rate was 11 percent in the unrelated children who never had been depressed."
Carney and his colleagues found similar patterns when they looked at smoking and physical activity.
"A third of those who were depressed as children had become daily smokers, compared to 13 percent of their nondepressed siblings and only 2.5 percent of the control group," he says.
In terms of physical activity, the teens who had been depressed were the most sedentary. Their siblings were a bit more active, and members of the control group were the most active.