title: Genetics of verbal working memory processes: a twin study of middle-aged men.
abstract: Genetic and environmental influences on cognitive components of reading span in 345 middle-aged male twin pairs were examined. Shared variance among word recognition (reading only), digits forward (short-term memory only), and reading span (concurrent reading plus memory) was almost entirely mediated by common genetic influences. Overall heritability was .52 for word recognition, .27 for digits forward, and .51 for reading span. All of the genetic influences on word recognition and digits forward, but only about one-half of the genetic influences on reading span, came from a common latent phenotype. The genetic influences that were specific to reading span were concluded to most likely reflect an executive function component. Implications for genetic studies of aging and prefrontal brain function are discussed.
authors.affiliation: Department of Psychiatry, Center for Behavioral Genomics, University of California, San Diego, CA 92093-0738, USA. wkremen@ucsd.edu
authors.forename: William S
authors.initials: WS
authors.lastname: Kremen
authors.forename: Kristen C
authors.initials: KC
authors.lastname: Jacobsen
authors.forename: Hong
authors.initials: H
authors.lastname: Xian
authors.forename: Seth A
authors.initials: SA
authors.lastname: Eisen
authors.forename: Lindon J
authors.initials: LJ
authors.lastname: Eaves
authors.forename: Ming T
authors.initials: MT
authors.lastname: Tsuang
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Lyons
mesh_terms: D000704:Analysis of Variance; D016001:Confidence Intervals; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D008875:Middle Aged; D008960:Models, Psychological; D009483:Neuropsychological Tests; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011932:Reading; D018433:Twin Studies as Topic; D014427:Twins / Q000235:genetics*; D014706:Verbal Learning / Q000502:physiology*