Associations between behaviour problems and verbal and non-verbal cognitive abilities and disabilities in early childhood

Background: We investigated associations between behaviour problems and verbal and nonverbal cognitive abilities at 2, 3 and 4 years of age both for the entire distribution and for the lowest 5% and 10% of the verbal and nonverbal cognitive disabilities.Methods: A community sample of 4,000 pairs of twins born in England and Wales in 1994 and 1995 was assessed by their parents at 2, 3 and 4 years using the Revised Rutter Parent Scale for Preschool Children (RRPSPC, behaviour problems), the MacArthur Communicative Development Inventory (MCDI, verbal development), and the Parent Report of Children's Abilities (PARCA, nonverbal cognitive development).Results: For the entire sample, behaviour problem scores were modestly associated with lower MCDI and PARCA scores – correlations were less than .30. Similarly modest effect sizes were found for relationships between behaviour problem scores and the lowest 5% and 10% of the MCDI and of the PARCA distributions. Associations were stronger for nonverbal than for verbal development, increased from 2 to 3 to 4 years, and, at the extremes of the distributions, were stronger for boys than for girls. Multivariate genetic analyses indicated that both genetic and shared environmental factors mediate the links between behaviour problems and cognitive development both for the total distribution and for the extremes. Genetic links may be stronger for the extremes than for the total sample.Conclusions: We conclude that, in this community sample of young children, associations between behaviour problems and verbal and nonverbal cognitive development are generally modest for the entire distribution and are no greater at the extremes than expected on the basis of the associations for the entire distribution

Temperament and Problem Behaviour during Early Childhood

Some evidence exists for the phenotypic association of problem behaviour in early childhood with temperament in infancy, but little is known about the genetic and environmental mechanisms mediating this association. At the ages of 14, 20, 24, and 36 months, mothers of twins completed the Colorado Childhood Temperament Inventory (CCTI; Buss & Plomin, 1984; Rowe & Plomin, 1977). At age 4, problem behaviour was assessed using maternal reports on the Child Behavior Checklist (CBCL/4-18; Achenbach, 1991). The temperamental trait of Emotionality at all four prior age points correlated signicantly with the CBCL Total Problem Score at 4 years as well as with the broad-band groupings of Internalising the Externalising. In addition, Shyness at all four ages correlated signicantly with the broad-band grouping of Internalising. Longitudinal behavioural genetic analyses indicated that these phenotypic predictions from early temperament to later behaviour problems are largely due to genetic factors. There is growing interest in clinical and developmental psychology in th

Twin's Birth-Order Differences in Height and Body Mass Index From Birth to Old Age: A Pooled Study of 26 Twin Cohorts Participating in the CODATwins Project

We analyzed birth order differences in means and variances of height and body mass index (BMI) in monozygotic (MZ) and dizygotic (DZ) twins from infancy to old age. The data were derived from the international CODATwins database. The total number of height and BMI measures from 0.5 to 79.5 years of age was 397,466. As expected, first-born twins had greater birth weight than second-born twins. With respect to height, first-born twins were slightly taller than second-born twins in childhood. After adjusting the results for birth weight, the birth order differences decreased and were no longer statistically significant. First-born twins had greater BMI than the second-born twins over childhood and adolescence. After adjusting the results for birth weight, birth order was still associated with BMI until 12 years of age. No interaction effect between birth order and zygosity was found. Only limited evidence was found that birth order influenced variances of height or BMI. The results were similar among boys and girls and also in MZ and DZ twins. Overall, the differences in height and BMI between first- and second-born twins were modest even in early childhood, while adjustment for birth weight reduced the birth order differences but did not remove them for BMI