A study of 18 Down Syndrome and 18 other mentally retarded adults found evidence of a significant erosion of Wechsler Intelligence Scale for Children scores from the third to fourth decades of life. The Block Design subtest was especially vulnerable to performance decline with age in the Down Syndrome adults. (Author/JDD)

The confluence model of cognitive development was tested on 7,060 children. Family size, sibling order within family sizes, and hypothesized age-dependent effects were tested. Findings indicated an inverse relationship between family size and the cognitive measures; age-dependent effects and other confluence variables were found to be…

Genetic influence was estimated on Wechsler Intelligence Scale for Children subtests from inbreeding depression scores calculated on cousin marriages in Japan (n=1,854 children) and correlated with American Black-White racial differences. The genetic contribution of racial differences in cognitive performance may be more robust than was previously…