MqTM, here's an article which puts a bit more meat on the bones of the NIH study whose findings have chosen to ignore. Read it carefully.
As the study progresses, we'll be able to see whether your theories are good. In the meantime, the results which are available seem to be contrary to your thinking.
It will be interesting to see what the findings are in the next 5 years or so. We can discuss them then if we are alive and remember,
medscape.com
May 18, 2007 — The first report from the National Institute of Health (NIH) Magnetic Resonance Imaging (MRI) Study of Normal Brain Development trial provides a glimpse into the brain performance of healthy children and shows how this is affected by sex, income, and age.
The findings are published online May 18 in the Journal of the International Neuropsychological Society.
"In some ways [this database] is a tool, just like the human genome project, and so I think this project is going to give researchers tools that will really advance the field in ways that we can't even imagine," lead author Deborah P. Waber, PhD, from the Children's Hospital Boston, in Massachusetts, told Medscape.
Longitudinal Study of Population-Based Sample
The goal of the NIH MRI Study of Normal Brain Development was to create a public database of imaging and neuropsychological data from the normal healthy developing brain from birth to young adulthood.
Participants were selected so that they were representative of the demographic diversity (race/ethnicity and income) of the US population in 2000, said Dr. Weber, adding that until now, researchers relied on samples of convenience. More than 35,000 families were targeted, and from these, 385 healthy children aged 6 to 18 years were enrolled at 6 pediatric centers in US cities. The children are being evaluated at 3 time points: at baseline and 2 and 4 years later.
The children underwent imaging tests and standard tests to assess intelligence, processing speed, verbal memory, verbal fluency, spatial memory, fine-motor dexterity, handedness, executive functions, academic skills (reading and calculating), and psychosocial function. The effects of sex, age, and income on task performance were determined.
This article describes the results of the neuropsychological evaluation of the children at baseline.
High-Performing Group, Less Dramatic Sex and Income Differences
"Not surprisingly, these children consistently outperformed published norms," the group writes, adding that this is likely due to the strict exclusion criteria for this study.
Girls performed better at tasks requiring processing speed and motor dexterity, and boys were better at perceptual analysis. Girls also tested better in verbal learning, but surprisingly, their performance declined through adolescence. There were no sex differences in calculation ability.
As expected, the low-income children had lower IQ scores, but the group outperformed population norms. Although the low-income children scored lower on tests of reading comprehension and calculation, they performed better than expected in single-word reading. This suggests that tasks that require greater integration of cognitive abilities (such as reading) are more vulnerable to poverty-related factors than are basic skills (such as single-word reading), the authors write.
Dr. Waber observed: "One of the things that stood out for me is that the differences according to income level were less dramatic than they sometimes are in other studies." She added that the participants were required to have no psychiatric, neurologic, or developmental problems, or any family history of these and no exposure to toxins, so not surprisingly, more potential low-income than high-income participants were excluded. A lot of cognitive differences that investigators have reported for low-income children may be due to health disparities that affect brain development, she noted.
Proficiency for most tasks improved dramatically between age 6 and 10 years and then leveled off during early adolescence (age 10 to 12 years), suggesting that children approach adult levels of ability to perform many neurocognitive tests. These preliminary findings are based on a single point in time and are averages of the performance of a whole population, so they cannot measure changes that continue to occur in adolescence, the authors caution. Longitudinal data from the second and third visits will provide more insight.
"This database will serve as an invaluable public resource for investigators for many years to come," the authors conclude. Dr. Waber added that this database provides "a benchmark of what a healthy brain will look like — both anatomically and in terms of function."
The study was funded by the National Institute of Neurological Disorders and Stroke, the National Institute of Mental Health, the National Institute of Child Health and Human Development, and the National Institute on Drug Abuse.
J Int Neuropsychol Soc. 2007. Published online May 18, 2007. |
