STEVE INSKEEP, host:
Take a look across America, and you can find more than a million and a half adopted children under the age of 18. That number grows by more than 100,000 every year. One question is: How is their emotional health affected?
Michelle Trudeau reports that researchers now have an answer.
MICHELLE TRUDEAU: People have wondered for a long time whether children who were adopted in infancy are at increased risk for psychological problems. Now, in the first study of its kind, research psychologist Margaret Keyes actually tested the psychological well-being of adopted teenagers.
Ms. MARGARET KEYES (Research Psychologist): We've assembled a sample of 692 adopted adolescents, all of whom had been adopted prior to 2 years of age.
TRUDEAU: In fact, the average child in this study went to live with their new family at only 4 months of age. When Keyes tested them, they were around 15 years old. They were given in-depth psychological interviews, checking for depression, anxiety, ADHD, and something called oppositional defiant disorder, or ODD.
Ms. KEYES: These are kids who argue with their parents, who refuse to follow through on chores, maybe argue with their teachers, blame other people for their own mistakes.
TRUDEAU: More than just a negative teenager, ODD is persistent hostility and disobedience. For comparison, Keyes gave the same extensive psychological work-up to a group of teenagers raised by their biological parents. The results are published this month in the Archives of Pediatric and Adolescent Medicine.
Ms. KEYES: We found that most of the adolescents, adopted and non-adopted, were psychologically healthy - overwhelmingly psychologically healthy.
TRUDEAU: That being said, Keyes did find what she calls an adoption effect.
Ms. KEYES: There's a slightly increased risk for the adopted kids, especially ADHD and oppositional defiant disorder.
TRUDEAU: This risk was doubled in the adopted teenagers. Keyes explains...
Ms. KEYES: So if you look at something like ADHD, for the non-adopted kids, about seven out of every 100 had a diagnosis of ADHD. For the adopted kids, it's more like 14 or 15 out of every hundred.
TRUDEAU: And similarly for oppositional defiant disorder - ODD - nearly a doubling of the risk. But there was no increased risk among adopted teenagers for depression or anxiety or for a form of serious delinquency that involves aggression, truancy, vandalism and the like.
David Brodzinski is professor emeritus from Rutgers University, a leader in the field of adoption research. He's not surprised that some psychological problems were doubled in a group of adopted children.
Professor DAVID BRODZINSKI (Rutgers University): Many of the serious problems associated with adoption have less to do with adoption per se than with what happens before adoption.
TRUDEAU: Such as genetic factors, the health of the biological parents, possible exposure to alcohol or drugs in utero. All these "before" factors impact the later mental health of a child. Brodzinski's own research finds that adopting parents are a special breed - highly motivated, better educated, better off financially than non-adopting parents. And now Margaret Keyes adds to this list. Adopting parents were also more likely to get help from mental health professionals for their adopted child when behavioral problems arose.
There's one more provocative finding from this study. Adopted children born in another country - most in this study came from South Korea - had slightly less ADHD than adopted children born in the United States. It's not clear why this may be the case.
For NPR News, I'm Michelle Trudeau.