Teens who were depressed as children are far more likely to be obese, smoke cigarettes and lead sedentary lives, which can increase the risk of heart problems later in life, according to new research.
The risk factors remain even if the teens no longer suffer from depression, according to the study conducted by researchers from the Washington University School of Medicine in St. Louis and the University of Pittsburgh.
“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,” said study author Robert M. Carney, Ph.D., 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.”
Depression in adults has long been associated with heart disease and a higher risk of dying from a heart attack or having serious complications, according to the researchers.
“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,” Carney said.
For the study, researchers gathered information from children who 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 had never been depressed. They also collected information from 161 unrelated children with no history of depression.
The researchers surveyed all of the children again in 2011, at the age of 16. The scientists looked at the 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 said. “Only 17 percent of their siblings were obese, and the obesity rate was 11 percent in the unrelated children who never had been depressed.”
The researchers 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 non-depressed siblings and only 2.5 percent of the control group,” he said.
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, the researcher noted.
When the research team used statistical methods to eliminate other factors that could have influenced smoking or obesity rates in the depressed children, they found that the effects of depression were even more pronounced.
“The siblings of depressed children were five times more likely to smoke than members of the study’s control group, so depression wasn’t the only risk factor for smoking,” he said. “But the depressed children in the study were another two-and-a-half times more likely to smoke than their non-depressed siblings.”
Heart disease risk factors were more common in formerly depressed children whether they were still clinically depressed at the time of the second survey, according to Carney. In fact, depression was in remission for most of the teens by 2011, with only 15 percent reporting depression, he said.
The findings suggest that any history of depression in childhood appears to influence the presence of cardiac risk factors in adolescence, according to Carney.
“Depression seems to come first,” he said. “It’s playing an important, if not a causal, role. There may be some related genetic influences that give rise to both depression and to heart disease, or at least to these types of cardiac risk behaviors, but more study will be required before we can draw any firm conclusions about that.”