Researchers have long suspected that abuse or neglect early in life can permanently alter people's brains, making them more prone to anxiety and depression, less able to handle stress, or even incapable of forming strong attachments with others. There has been little molecular evidence to back this up, however. Now a group reports that children who started life as neglected orphans show long-term deficiencies in hormones related to social attachment.
Hormones play an important role in our interactions with others. Oxytocin levels increase during warm physical interactions with a familiar person, and vasopressin is related to recognizing familiar people. Studying these hormones has proven difficult in small children, however, because they have to be obtained via blood samples or spinal taps.
Psychologist Seth Pollak of the University of Wisconsin, Madison, and colleagues say they have finally figured out how to measure oxytocin and vasopressin levels in urine. Using this technique, described in the 21 November online Proceedings of the National Academy of Sciences, the researchers studied 18 children approximately 4 years old who had spent an average of 16 months in orphanages before being adopted. The team compared this group to 21 children raised by their biological parents. Both groups participated in two scenarios: In one, the child played a computer game while interacting with its mother for 30 minutes; in the other, the child did the same thing with a strange woman.
The scenes may have looked the same to a casual observer, but, on the inside, the former orphans reacted much differently than their counterparts. Kids raised by their biological parents experienced a rise in oxytocin levels after contact with their mothers but not with the stranger. That makes sense, Pollak says, because the hormone has been shown to decrease stress. "Close proximity to a parent helps a young child to get the stress system under control," says Pollak. Former orphans, on the other hand, showed no change in oxytocin levels in either situation. Former orphans also had lower levels of vasopressin in both scenarios, he says, which could help explain why they have difficulty making friends.
Thomas Insel, director of the National Institute of Mental Health, notes that the report is consistent with evidence not only from animal studies but also from the fact that children with autism--who avoid social interactions--also show decreases in oxytocin. But he says he's skeptical of the urine technique because "no one has developed a noninvasive method to measure oxytocin or vasopressin before." However, he says, "if this is an accurate method, it could jumpstart a new approach to clinical studies."