Article

Longitudinal and cross-sectional twin data on cognitive abilities in adulthood: The Swedish Adoption/Twin Study of Aging.

Division of Social Sciences, Indiana University Southeast, New Albany 47150, USA.
Developmental Psychology (Impact Factor: 3.21). 12/1998; 34(6):1400-13. DOI: 10.1037//0012-1649.34.6.1400
Source: PubMed

ABSTRACT Cross-sequential methods of analysis, designed to separate age and cohort effects, were applied to data from the Swedish Adoption/Twin Study of Aging. Thirteen cognitive variables were collected at 3 times of measurement separated by 3-year intervals. Data were available from 85 individuals from monozygotic (MZ) pairs reared apart, 132 from MZ pairs reared together, 207 from dizygotic (DZ) pairs reared apart, and 178 from DZ pairs reared together (age range at first assessment: 41-84 years). Time x Cohort interactions were found for mean performance on 8 of the measures, revealing stable mean performance in the younger cohorts and longitudinal decreases in mean performance in the older cohorts. Cohort and time effects for total variance were mixed; little evidence was found for increases in variance with age. Age changes and cohort differences in genetic and environmental components of variance were test-specific; several Cohort x Time interactions attained significance. Heritability of the general cognitive ability factor showed significant longitudinal decreases over time in the older cohorts.

0 Followers
 · 
51 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Telomeres prevent the loss of coding genetic material during chromosomal replication. Previous research suggests that shorter telomere length may be associated with lower survival. Because genetic factors are important for individual differences in both telomere length and mortality, this association could reflect genetic or environmental pleiotropy rather than a direct biological effect of telomeres. We demonstrate through within-pair analyses of Swedish twins that telomere length at advanced age is a biomarker that predicts survival beyond the impact of early familial environment and genetic factors in common with telomere length and mortality. Twins with the shortest telomeres had a three times greater risk of death during the follow-up period than their co-twins with the longest telomere measurements [hazard ratio (RR) = 2.8, 95% confidence interval 1.1-7.3, P = 0.03].
    Aging cell 01/2008; 6(6):769-74. DOI:10.1111/j.1474-9726.2007.00340.x · 5.94 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Genetic influences on brain morphology and IQ are well studied. A variety of sophisticated brain-mapping approaches relating genetic influences on brain structure and intelligence establishes a regional distribution for this relationship that is consistent with behavioral studies. We highlight those studies that illustrate the complex cortical patterns associated with measures of cognitive ability. A measure of cognitive ability, known as g, has been shown highly heritable across many studies. We argue that these genetic links are partly mediated by brain structure that is likewise under strong genetic control. Other factors, such as the environment, obviously play a role, but the predominant determinant appears to be genetic.
    Annual Review of Neuroscience 02/2005; 28:1-23. DOI:10.1146/annurev.neuro.28.061604.135655 · 22.66 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The Swedish Adoption/Twin Study of Aging is a semilongitudinal study of the aging of mental abilities in monozygotic and dizygotic twins. In the article by D. Finkel, N. L. Pedersen, R. Plomin, and G. E. McClearn (1998), data from 602 individuals were used to investigate developmental changes on 14 measures of mental ability as well as changes in the heritability of these abilities. This commentary details a number of problems with the design and analysis of data reported by Finkel et al., problems that leave the results difficult to interpret, and then provides suggestions for more fruitful approaches for analyzing data from such studies in the future.
    Developmental Psychology 12/1998; 34(6):1414-6. DOI:10.1037//0012-1649.34.6.1414 · 3.21 Impact Factor