NIH study reveals Brain development process

A study conducted by the psychologists and psychiatrists of National Institutes of Health (NIH) assessed children’s mental acuity and social skills in order to track their brain growth and behavior, concluding that a child’s brain develops the most till adolescence, as published on Friday in the online edition of the Journal of the International Neuropsychological Society.

Researchers from the National Institutes of Health targeted around 35,000 youngsters aged between 6 to 18 years and screened them for medical, neuralgic and psychiatric disorders, as well as for family histories pointing towards hereditary problems or prenatal exposure to toxins and short listed around 450 children that met the “healthy children” criteria.

Dr. James C. Harris, a professor of psychiatry and pediatrics at the Johns Hopkins University School of Medicine, said the rigorous screening process probably identified a particularly healthy group of children.

The study, beginning in 1999 and led by Deborah Waber of Children's Hospital Boston, lasted for six whole years in which the experts studied children from different age groups. The data of different children were integrated to track the trend of brain development and formation of neural connections analyzing the changes in brain chemistry from birth to adulthood.

Magnetic Resonance Imaging (MRI) scans of the brain and other tests to determine IQ, verbal ability, mental processing speed, spatial ability, memory, fine motor dexterity, psychosocial function, reading and calculation ability, and other measures of psychological function were conducted revealing that a child’s grasp on such cognitive tasks improves rapidly between age 6 and 10, but levels off thereafter and improves very slightly or not at all during adolescence because before attaining the age of 12 years the brain makes more connections between nerve cells that in turn enlarge vital regions. After puberty, the process slows and the brain "prunes" itself, focusing less on installing new wiring than on programming and refining what is already there.

"The basic building blocks seem to be in place by the time someone reaches 11 or 12," Waber said.

"It's not just that the brain gets bigger. Certain structures in the brain become smaller or change shape. To actually see any changes in the connections in the brain and relate it to function is going to be very interesting," Waber added.

The scientists had to face some difficulty conducting the MRI tests of restless children as the MRI image become blurred if the object under the scanner moves. The scientists, unable to sedate healthy children, put small children under the scanners while they were sleeping with earplugs on to avoid waking them up with the sound of noisy machines. Six year olds were made to wear earphones and watch their favorite videos while they were tested under the scanner.

Careful analysis and scrutiny also helped the scientists to extend their research to the understanding of the nexus between brain behavior and gender or family income.

The study found less difference between the mental performance levels of boys and girls. However supporting the earlier findings, it was revealed that girls seem to have slight advantage on perceptual analysis like processing speed and motor dexterity and boys are better at perceptual analysis i.e. analyzing and manipulating shapes and patterns.

"We found a few significant differences that we would have suspected," Waber said. "For example, boys are better at visual and spatial tasks, and girls are better at motor speed, but there are no differences in many other paths, like memory."

The survey report also showed that children from families with higher income do better than the lower-income family kids and had a better IQ level helping them to execute complex tasks reading comprehension easily. Children classified as low (less than $35,000 per year), middle ($35,000 to $75,000) and high-income (over $75,000) had average IQs of 105, 110 and 115, respectively, thus IQ’s are believed to have increased alongside with income.

"But when we limit the groups to healthy children, the differences are not as great," Waber said. "That suggests that the difference has more to do with disparity in health care related to income."

These scientists also hope to get secondary findings relating to the underlying causes of developmental problems such as attention deficit disorder and autism among children. Thus the scientists call their study an incomplete picture and are hopeful of overcoming their drawbacks in future.

"This database will be like a library of brains that investigators can use to compare to other populations of children with disease and disorders," said Deborah P. Waber

This new research as compared to an earlier research which was conducted without the MRI test showed a narrow gap between the children from rich and poor families owing to the better screening procedure.

A normal brain grows at an amazing rate during development and at times 250,000 neurons are added every minute. It’s also believed that by the age of 2 years the brain is 80% the size of the adult brain.