title: Quantitative genetic analysis of latent growth curve models of cognitive abilities in adulthood.
abstract: Though many cognitive abilities exhibit marked decline over the adult years, individual differences in rates of change have been observed. In the current study, biometrical latent growth models were used to examine sources of variability for ability level (intercept) and change (linear and quadratic effects) for verbal, fluid, memory, and perceptual speed abilities in the Swedish Adoption/Twin Study of Aging. Genetic influences were more important for ability level at age 65 and quadratic change than for linear slope at age 65. Expected variance components indicated decreasing genetic and increasing nonshared environmental variation over age. Exceptions included one verbal and two memory measures that showed increasing genetic and nonshared environmental variance. The present findings provide support for theories of the increasing influence of the environment with age on cognitive abilities.
authors.affiliation: Department of Psychology, University of California, 1344 Olmstead Hall, Riverside, CA 92521, USA. chandra.reynolds@ucr.edu
authors.forename: Chandra A
authors.initials: CA
authors.lastname: Reynolds
authors.forename: Deborah
authors.initials: D
authors.lastname: Finkel
authors.forename: John J
authors.initials: JJ
authors.lastname: McArdle
authors.forename: Margaret
authors.initials: M
authors.lastname: Gatz
authors.forename: Stig
authors.initials: S
authors.lastname: Berg
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Pedersen
mesh_terms: D000300:Adoption; D000368:Aged; D000375:Aging / Q000235:genetics* / Q000523:psychology*; D003071:Cognition; D003072:Cognition Disorders / Q000235:genetics; D004777:Environment; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory; D008875:Middle Aged; D008962:Models, Theoretical; D013548:Sweden