title: Genetic complexity of episodic memory: a twin approach to studies of aging.
abstract: Episodic memory change is a central issue in cognitive aging, and understanding that process will require elucidation of its genetic underpinnings. A key limiting factor in genetically informed research on memory has been lack of attention to genetic and phenotypic complexity, as if "memory is memory" and all well-validated assessments are essentially equivalent. Here we applied multivariate twin models to data from late-middle-aged participants in the Vietnam Era Twin Study of Aging to examine the genetic architecture of 6 measures from 3 standard neuropsychological tests: the California Verbal Learning Test-2, and Wechsler Memory Scale-III Logical Memory (LM) and Visual Reproductions (VR). An advantage of the twin method is that it can estimate the extent to which latent genetic influences are shared or independent across different measures before knowing which specific genes are involved. The best-fitting model was a higher order common pathways model with a heritable higher order general episodic memory factor and three test-specific subfactors. More importantly, substantial genetic variance was accounted for by genetic influences that were specific to the latent LM and VR subfactors (28% and 30%, respectively) and independent of the general factor. Such unique genetic influences could partially account for replication failures. Moreover, if different genes influence different memory phenotypes, they could well have different age-related trajectories. This approach represents an important step toward providing critical information for all types of genetically informative studies of aging and memory.
authors: Department of Psychiatry, Center for Behavioral Genomics.
authors: William S
authors: WS
authors: Kremen
authors: Department of Psychiatry, Center for Behavioral Genomics.
authors: Matthew S
authors: MS
authors: Panizzon
authors: Department of Psychiatry, Center for Behavioral Genomics.
authors: Carol E
authors: CE
authors: Franz
authors: Department of Psychiatry, Center for Behavioral Genomics.
authors: Kelly M
authors: KM
authors: Spoon
authors: Department of Psychiatry, Center for Behavioral Genomics.
authors: Eero
authors: E
authors: Vuoksimaa
authors: Department of Psychiatry and Behavioral Neuroscience, University of Chicago.
authors: Kristen C
authors: KC
authors: Jacobson
authors: Department of Psychiatry and Behavioral Neuroscience, University of Chicago.
authors: Terrie
authors: T
authors: Vasilopoulos
authors: Department of Biostatistics, St. Louis University.
authors: Hong
authors: H
authors: Xian
authors: Department of Psychiatry and Human Behavior.
authors: Jeanne M
authors: JM
authors: McCaffery
authors: Department of Psychiatry, Center for Behavioral Genomics.
authors: Brinda K
authors: BK
authors: Rana
authors: Department of Psychology, Boston University.
authors: Rosemary
authors: R
authors: Toomey
authors: Department of Psychology, Boston University.
authors: Ruth
authors: R
authors: McKenzie
authors: Department of Psychology, Boston University.
authors: Michael J
authors: MJ
authors: Lyons
mesh_terms: D000375:Aging / Q000235:genetics* / Q000523:psychology*; D003071:Cognition / Q000502:physiology; D006801:Humans; D007802:Language; D008297:Male; D061212:Memory, Episodic; D011939:Mental Recall / Q000502:physiology; D008875:Middle Aged; D015999:Multivariate Analysis; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D014427:Twins / Q000235:genetics / Q000523:psychology; D014728:Veterans