Comparison of the mental status of 30 subjects with Down's Syndrome mosaicism and 30 matched subjects with trisomy 21 Down's Syndrome found that the mean intelligent quotient of the mosaic Down's Syndrome group was significantly higher and that this group showed better verbal abilities and more normal visual-perceptual skills. (Author/DB)

Down Syndrome children (N=229), aged 1-83 months, from Australia, Canada, and Germany were tested using the Bayley Scales of Infant Development. Test performances on the Bayley's Mental and Motor scales were not dissimilar, leading to the conclusion that young Down Syndrome children from different countries with relatively comparable standards of…

A study designed to examine biological, sociological, and early maturational correlates of intelligence collected data prospectively, from birth to 15 years of age, on a sample of 987 black children. Multiple indicators of eight independent and three dependent variables were tested in a structural equation model. Altogether, clear sex differences…