Midlife Study of the Louisville Twins: Connecting Cognitive Development to Biological and Cognitive Aging

Genetic and environmental correlates of the nonlinear recovery of cognitive ability in Twins.

“…In the only other study to model the growth of standardized cognitive scores in twins across childhood, von Stumm and Plomin (2015) observed patterns of cognitive development that approached positive and negative infinity over time based on quadratic growth models. Ongoing LTS work has observed moderate correlations between cognitive ability in childhood and cognitive functioning in midlife in pilot data (Beam et al, 2020), and a central goal of ongoing work is to extend childhood trends in growth of cognitive ability across childhood to cognitive functioning in midlife. However, polynomial models have extremely limited utility in predicting later-life outcomes from childhood data (Grimm et al, 2011).…”

“…In a series of studies using prospective data from the Louisville Twin study (LTS), Ronald Wilson documented the delay in early cognitive ability in twins (Wilson, 1972(Wilson, , 1974(Wilson, , 1975 as well as the subsequent recovery to performance at the population mean, which was observed to occur by age 6 (Wilson, 1974(Wilson, , 1975. Since the publication of Wilson's seminal papers, the sample size of the LTS has nearly doubled and standardized cognitive data have been collected to age 15 years (Davis et al, 2019), and is currently being collected in midlife (Beam et al, 2020). The present study builds on early LTS research and applies contemporary nonlinear growth methods to quantify the magnitude and shape of recovery of twins' standardized cognitive ability from 3 months to 15 years.…”

Socioeconomic status impacts genetic influences on the longitudinal dynamic relationship between temperament and general cognitive ability in childhood: The Louisville Twin Study

“…As the first application of bivariate dual change score models to the relationship between temperament and cognition, the current analysis focused on full-scale GCA scores. Assessing GCA from age 4 to 9 years involves changes in measurement (WPPSI to WISC) that would require some degree of harmonization to support analyses at the level of individual tests, although those harmonization attempts are ongoing with LTS data ( Beam et al, 2020 ). Subsequent analyses will focus on specific components of cognition and their relationship with specific components of temperament.…”

“…Data collection for the LTS ran from 1957 until the late 1990s, generating arguably the most comprehensive data on the early development of U.S. twins ever collected ( Rhea, 2015 ). Even as the LTS revisits the twins now in middle age to expand the longitudinal assessment ( Beam et al, 2020 ), representativeness of the sample has always been a concern, in part because of little migration away from Louisville, Kentucky and the ongoing addition of new sets of twins that introduces possible cohort effects. The LTS research group is addressing these concerns directly by addressing the effect test version has on age-to-age differences in cognitive development scores ( Giangrande et al, in press ).…”

Genetically informed, multilevel analysis of the Flynn Effect across four decades and three WISC versions

“…As mentioned above, the LTS team is in the process of entering previously unanalyzed item‐level WISC data, which will enable more sophisticated modeling of within‐person change. Soon, it will be possible to extend LTS analyses of the FE across much of the life span; cognitive ability data are available starting at 3 months of age, and a current project is collecting adult cognitive ability data on the twins at midlife (Beam et al, 2020). These efforts will further the field's understanding of the FE and how to measure and control for it, both in the LTS and other studies of cognitive development.…”