 Additionally, test scores for older children (aged 13 years old or older) tend to be higher than those of younger children (under 12 years old), though the difference is small and not significant.This is explained with the consideration of the development and maturation of children at this age level, with changes occurring in brain structure occurring at these ages.One study, however, reported that the CDI scores of younger (aged 6–11) children were higher than those of older (aged 12–18) children.