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Biomedical subjects

J C DeFries

Publications and source records attributed to J C DeFries.

At least 73 records · Page 4Linked to original sources
PubMed1986

Longitudinal stability of cognitive ability from infancy to early childhood: genetic and environmental etiologies.

A path model of genetic and shared family environmental transmission was fitted to general cognitive ability data from 1-, 2-, 3-, and 4-year-old adopted and nonadopted children and their parents in order to assess the etiology of longitudinal stability from infancy to early childhood. Stability across years is moderate and is due mainly to influences not predicted by parental IQ. Results of the present study, in conjunction with those of previous twin studies, suggest substantial genetic stability from infancy and early childhood to adulthood.

Adoption↗
PubMed1984

Cognitive abilities in reading-disabled children: a longitudinal study.

Longitudinal psychometric test data collected at two different ages (9.4 +/- 1.3 and 14.8 +/- 1.2 years) were utilized to compare the developmental rates of 69 pairs of reading-disabled and matched control children. Results of a two-factor (GROUP X TIME), mixed-model, multivariate analysis of variance indicated that reading-disabled children manifested deficits on measures of academic achievement, symbolic processing speed and spatial reasoning abilities at both ages. Although both reading-disabled and control children were found to improve significantly between the two testing sessions, the lack of a significant GROUP X TIME interaction on measures of academic achievement and spatial reasoning abilities indicated that the rate of development was similar for the two groups. For measures of symbolic processing speed, however, differences between reading-disabled and control children were somewhat greater at the later age.

Achievement↗
PubMed1983

The Colorado Adoption Project.

This report provides an overview of the Colorado Adoption Project (CAP), a longitudinal, prospective, multivariate adoption study of behavioral development. Examples of the types of analyses that can be conducted using this design are presented. The examples are based on general cognitive-ability data for adoptive, biological, and control parents; assessments of their home environment; and Bayley Mental Development Index scores for 152 adopted children and 120 matched control children tested at both 1 and 2 years of age. The illustrative analyses include matched control children tested at both 1 and 2 years of age. The illustrative analyses include examination of genetic and environmental sources of variance, identification of environmental influence devoid of genetic bias, assessment of genotype-environment interaction and correlation, and analyses of the etiology of change and continuity in development.

Adoption↗
PubMed1983

Longitudinal stability of cognitive ability in the Colorado Adoption Project.

Measures of general cognitive ability in 1- and 2-year-old adopted and nonadopted infants and their parents were subjected to path analysis to estimate the contribution of genetic and environmental factors to short-term stability. Although significant genetic influences were found at both 1 and 2 years of age, no significant environmental influences shared by parents and children were observed at these ages. Short-term stability of mental ability between the 2 ages was relatively independent of both between-family genetic and environmental influences. However, genetic factors may contribute importantly to long-term stability.

Adoption↗
PubMed1983

Parental contributions to longitudinal stability of cognitive measures in the Colorado Family Reading Study.

Data on reading-disabled and control probands and their families tested in the Colorado Family Reading Study were subjected to a comprehensive longitudinal-familial path analysis. Covariance matrices were constructed from composite scores for reading performance and for coding and symbol processing speed, and maximum likelihood estimates of familial parameters were obtained. With regard to the reading data, these estimates suggest that parental influences contribute importantly to longitudinal stability for reading-disabled children but not for controls. Such a difference in covariance structure between the 2 types of families could be due to a gene (or genes) with major effect. In the case of coding and symbol processing speed, covariance structure is similar for the 2 types of families, and combined parameter estimates indicate that parental contributions to longitudinal stability for this measure are relatively unimportant.

Adolescent↗