A US National Institutes of Health (NIH) study into brain development during childhood is creating a database as a benchmark against which researchers on other studies can compare their data.

Scientists will be able to apply to the NIH for access to the database once it is ready, probably before the end of the year. They could, for example, compare structural or behavioural data from their studies of a mental disorder against those for children with 'normal' brains.

A database of scans will offer a picture of a normal child's brain. Credit: SOVEREIGN, ISM/SPL

The study, called the MRI Study of Normal Brain Development, is building a database of what constitutes a 'normal' child. Five hundred children aged from 7 days to 18 years, and representative of US society, have been recruited from six centres. Those with, or at risk of, any neurological or psychiatric disorders were screened out of the study. All were given a magnetic resonance imaging (MRI) scan, which shows the size of the brain's structures and the densities of grey and white matter, as well as tracks of fibres connecting areas in the brain. The children also took behavioural and cognitive tests.

The first results of the study, on neuropsychological tests in 6–18-year-olds, were published on 18 May (D. P. Waber et al. J. Int. Neuropsychol. Soc. doi:10.1017/S1355617707070841; 2007). They show that cognitive skills improve between the ages of 6 and 10 but level off during adolescence — contradicting a widespread belief that cognitive development 'spurts' during adolescence.

Researchers also confirmed that children's abilities in some cognitive tasks differ between boys and girls, and that cognitive performance correlates positively with parental income. But the differences were smaller than those seen in other studies. “We don't know why,” says NIH project officer Katrina Gwinn. “It may be the way we selected our sample, or we may know less about biases in our psychological tests than we like to think.”

More data will be added when later parts of the study are analysed. First data from another part of the study, involving around 100 babies aged up to 4.5 years scanned at more frequent intervals, will probably be published before the end of the year.