title: Heritability of cognitive functions in families of successful cognitive aging probands from the Central Valley of Costa Rica.
abstract: We sought to identify cognitive phenotypes for family/genetic studies of successful cognitive aging (SCA; maintaining intact cognitive functioning while living to late old age). We administered a battery of neuropsychological tests to nondemented nonagenarians (n = 65; mean age = 93.4 ± 3.0) and their offspring (n = 188; mean age = 66.4 ± 5.0) from the Central Valley of Costa Rica. After covarying for age, gender, and years of education, as necessary, heritability was calculated for cognitive functions at three pre-defined levels of complexity: specific neuropsychological functions (e.g., delayed recall, sequencing), three higher level cognitive domains (memory, executive functions, attention), and an overall neuropsychological summary. The highest heritability was for delayed recall (h² = 0.74, se = 0.14, p < 0.0001) but significant heritabilities involving memory were also observed for immediate recall (h² = 0.50), memory as a cognitive domain (h² = 0.53), and the overall neuropsychological summary (h² = 0.42). Heritabilities for sequencing (h² = 0.42), fluency (h² = 0.39), abstraction (h² = 0.36), and the executive functions cognitive domain (h² = 0.35) were also significant. In contrast, the attention domain and memory recognition were not significantly heritable in these families. Among the heritable specific cognitive functions, a strong pleiotropic effect (i.e., evidence that these may be influenced by the same gene or set of genes) for delayed and immediate recall was identified (bivariate statistic = 0.934, p < 0.0001) and more modest but significant effects were found for four additional bivariate relationships. The results support the heritability of good cognitive function in old age and the utilization of several levels of phenotypes, and they suggest that several measures involving memory may be especially useful for family/genetic studies of SCA.
authors: Department of Psychiatry, University of California San Diego, La Jolla, CA, USA.
authors: Tiffany A
authors: TA
authors: Greenwood
authors: Michal S
authors: MS
authors: Beeri
authors: James
authors: J
authors: Schmeidler
authors: Daniel
authors: D
authors: Valerio
authors: Henriette
authors: H
authors: Raventós
authors: Lara
authors: L
authors: Mora-Villalobos
authors: Karla
authors: K
authors: Camacho
authors: José R
authors: JR
authors: Carrión-Baralt
authors: Gary
authors: G
authors: Angelo
authors: Laura
authors: L
authors: Almasy
authors: Mary
authors: M
authors: Sano
authors: Jeremy M
authors: JM
authors: Silverman
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000235:genetics*; D001288:Attention / Q000502:physiology; D003072:Cognition Disorders / Q000453:epidemiology / Q000235:genetics*; D003364:Costa Rica / Q000453:epidemiology; D056344:Executive Function / Q000502:physiology; D005192:Family Health; D005260:Female; D008040:Genetic Linkage; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000235:genetics*; D011939:Mental Recall / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D021641:Recognition, Psychology / Q000502:physiology*; D035781:Siblings; D014706:Verbal Learning