There’s mounting evidence that growing up poor can lead to worse health in adulthood. But it’s not poverty per se that takes a life-shortening toll on the body. Children who grow up amid poverty and also endure harsh discipline from parents or other violence-related threats age faster than their peers. Their biological clock is older than their chronological age, reveals DNA in two pioneering scientific studies. Both will be presented at the American Psychosomatic Society meeting in Vancouver.
In the first study, 318 African-American adolescents aged 16 and 17 reported on how much harsh discipline their parents had used—slapping, hitting, shouting. As part of a long-term study, researchers knew the economic status of their family and neighborhood, their parents’ depression levels and employment status. These teens also were asked about experiences of racial discrimination. Then, at age 20, blood samples were taken to find out their biological age. This is shown by the pattern of methylation on DNA from their immune cells, explains lead study author Katherine Ehrlich, PhD, Assistant Professor of Psychology at the University of Georgia and Center for Family Research.
“None of the factors we looked at was linked to biological aging if these teenagers had low levels of harsh parenting,” says Ehrlich, “but these risk factors were significantly associated with being older than their chronological age when teens experienced harsh parenting.” And these youths who showed a sped-up biological clock at age 20 were significantly more likely to have metabolic syndrome in a follow-up at age 27, she adds. Metabolic syndrome is a cluster of medical conditions that increases the risk of heart disease, stroke and diabetes.
“It underscores how much parents matter,” says Ehrlich. Parents with scant economic resources can’t always shield their youngsters from upsetting experiences they have no control over. “This is a way, though, that parents can protect their children—by not being very harsh with discipline.” Children raised with more consistently loving parents may learn they can trust people, so they might feel less stressed, a boon for health. Whatever the reason, gentler parenting seems to prevent this premature aging.
The feeling of threat as a possible cause of biological aging also surfaced in a study of 247 children, 8 to 16 years old. Children and their caregivers were asked about how exposed the kids were to such threat-related experiences as physical, emotional or sexual abuse, as well as other violence in their lives, including exposure to domestic violence. They also were asked about deprivation-related experiences, including physical neglect, hunger and lack of cognitive stimulation. Then their DNA methylation was evaluated, as was stage of puberty. Again, deprivation per se, even going hungry, wasn’t associated with an older biological age. However, threat-related experiences were linked to both accelerated DNA methylation age and being at a more advanced stage of puberty than average for their age. Older DNA methylation age also was associated with greater symptoms of depression. Children who experience earlier puberty are at higher than average risk for depression, anxiety and substance abuse.
“What we found is that the impact of threat-related early experiences could be detected in kids as young as 8 years old,” says lead study author Jennifer Sumner, PhD, Assistant Professor of Behavioral Medicine at Columbia University Medical Center. Cutting-edge studies that use DNA methylation to measure biological age “are beginning to unravel how the types of adverse experiences kids have early on get under the skin and cause them to age,” says Sumner.
“We are beginning to learn that different types of early life adversity can have different developmental consequences,” notes Sumner. In the future, accelerated DNS methylation age and pubertal age could be used to identify youth who might be developing faster than expected given their chronological age, and who might benefit from health-related services.
The American Psychosomatic Society (APS) (www.psychosomatic.org), founded in 1943, is an international multidisciplinary academic society that organizes an annual scientific meeting and educational programs. Psychosomatic Medicine is its scientific journal. The membership of over 700 is composed of academic scientists and clinicians in medicine, psychiatry, epidemiology, health psychology and allied health services. The mission of the APS is “to advance and integrate the scientific study of biological, psychological, behavioral and social factors in health and disease.”