Our family lives in Chuck Nelson's former home -- including our three adopted children. We lived across the alley when he was a University of Minnesota professor traveling to Romania for a study that was recently published in Science (emphases mine).
The key feature of the study, and why it's both remarkable and controversial, is that the orphans were randomly assigned to either foster care or institutionalized care.
A report of the results has appeared in today's NYT... [btw. I think there's a significant error in the article, the author has confused foster care with adoption.]
Psychologists have long believed that growing up in an institution like an orphanage stunts children’s mental development but have never had direct evidence to back it up.
Now they do, from an extraordinary years-long experiment in Romania that compared the effects of foster care with those of institutional child-rearing.
The study, being published on Friday in the journal Science, found that toddlers placed in foster families developed significantly higher I.Q.’s by age 4, on average, than peers who spent those years in an orphanage.
The difference was large — eight points — and the study found that the earlier children joined a foster family, the better they did. Children who moved from institutional care to families after age 2 made few gains on average, though the experience varied from child to child. Both groups, however, had significantly lower I.Q.’s than a comparison group of children raised by their biological families.
... previous attempts to compare institutional and foster care suffered from serious flaws, mainly because no one knew whether children who landed in orphanages were different in unknown ways from those in foster care. Experts said the new study should put to rest any doubts about the harmful effects of institutionalization — and might help speed up adoptions from countries that still allow them...
...In recent years many countries, including Romania, have banned or sharply restricted American families from adopting local children. In other countries, adoption procedures can drag on for many months. In 2006, the latest year for which numbers are available, Americans adopted 20,679 children from abroad, more than half of them from China, Guatemala and Russia.
The authors of the new paper, led by Dr. Charles H. Zeanah Jr. of Tulane and Charles A. Nelson III of Harvard and Children’s Hospital in Boston, approached Romanian officials in the late 1990s about conducting the study. The country had been working to improve conditions at its orphanages, which became infamous in the early 1990s as Dickensian warehouses for abandoned children.
After gaining clearance from the government, the researchers began to track 136 children who had been abandoned at birth. They administered developmental tests to the children, and then randomly assigned them to continue at one of Bucharest’s six large orphanages, or join an adoptive family. [jf: I think this is a NYT error. They would have been randomized to foster care, not an adoptive family. ] The foster families were carefully screened and provided “very high-quality care,” Dr. Nelson said.
On I.Q. tests taken at 54 months, the foster children scored an average of 81, compared to 73 among the children who continued in an institution. The children who moved into foster care at the youngest ages tended to show the most improvement, the researchers found.
The comparison group of youngsters who grew up in their biological families had an average I.Q. of 109 at the same age, found the researchers, who announced their preliminary findings as soon in Romania as they were known....
Many nations dislike international adoption, even when foster care is not affordable and local adoption is not available. Well, if American girls were being adopted in China (maybe one day!) Americans would be pretty hostile to the idea too. The alternative though, is often orphanages. The study suggests that even the best orphanages Rumania can afford are not the equal of foster care; presumably international adoption would produce better outcomes.
The 8 point IQ gap (higher for the younger fostered children) is significant and it suggests a bigger post-natal influence on IQ than I'd have expected. On the other hand the 8 point gap pales next to the 36 point gap between a comparison group of non-orphans and children in orphanages.
Some of that may be related to breast feeding, but one recent study found only a 7 pt impact there related to breast feeding.
Children were not randomized between birth families and orphanages (I don't think that study is going to be done), so we don't know where the 36 point gap comes from.
We can make some guesses however. It is likely that the primary cause of admission to an orphanage in Rumania is extreme poverty in one or both birth parents. There are two strong relationships between poverty and IQ. On the one hand poverty is associated with malnutrition and a marginal intrauterine environment that harms brain development. On the other hand low IQ reduces earning power. IQ is significantly inherited, so children orphaned by poverty have both environmental and genetic risk factors impacting IQ.
Add in the impact of no breastfeeding and I think we can account for a 36 point IQ gap.