New evidence: Mental health problems in teenagers may be traceable to early-life stress

Parents' complaints about sudden mood swings of teenagers are common, but new research shows that children who experience early-life stresses such as abuse, neglect, or loss of a parent have an increased risk in adolescence of behavioral and emotional disorders.

The research, conducted on rhesus macaque monkeys at the Oregon National Primate Research Center at Oregon Health & Science University and at the University of Pittsburgh, suggests that adolescents who have been exposed to early-life stress have a greater incidence of developing an attachment disorder, attention deficit hyperactivity disorder, conduct disorder, anxiety, depression, suicide, drug abuse, and post-traumatic stress disorder.

"Until now, only human observation and theories have suggested that early-life stresses can also lead to problems as far away as the teenage years. By studying a species that has responses to early-life stresses that are very similar to young children, we can get a developmental picture that is much clearer than in humans," said Judy Cameron, PhD, a senior scientist in the divisions of Reproductive Sciences and Neuroscience at the OHSU Oregon National Primate Research Center.

For this study, researchers reared the monkeys with a one-time stress exposure-namely, having their mother removed from the social group at various stages early in their life-followed by rearing in a very stable social environment. The findings provide strong evidence that stress exposure early in life can have dramatic, long-lasting effects that persist into the teenage years and, perhaps, even adulthood.

Some infant monkeys had their mother removed from the social group when they were 1 week old. These infants went on to be alert and active but to show less-than-normal interest in social interactions. Their behavior looked similar to children who develop a form of attachment disorder characterized by withdrawal from social interactions.

In adolescence, one-week-separated monkeys continued to spend less time in social contact with other monkeys, and showed more time displaying self-comforting behaviors, especially when they were placed in mildly stressful situations.