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- McClearn, GE, et al.
(författare)
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Substantial genetic influence on cognitive abilities in twins 80 or more years old
- 1997
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Ingår i: Science (New York, N.Y.). - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 276:5318, s. 1560-1563
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Tidskriftsartikel (refereegranskat)abstract
- General and specific cognitive abilities were studied in intact Swedish same-sex twin pairs 80 or more years old for whom neither twin had major cognitive, sensory, or motor impairment. Resemblance for 110 identical twin pairs significantly exceeded resemblance for 130 fraternal same-sex twin pairs for all abilities. Maximum-likelihood model-fitting estimates of heritability were 62 percent for general cognitive ability, 55 percent for verbal ability, 32 percent for spatial ability, 62 percent for speed of processing, and 52 percent for memory. There was also evidence for the significant influence of idiosyncratic experience as the environmental component that most determines individual differences in cognitive abilities late in life.
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- Petrill, SA, et al.
(författare)
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The genetic and environmental relationship between general and specific cognitive abilities in twins age 80 and older
- 1998
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Ingår i: PSYCHOLOGICAL SCIENCE. - : SAGE Publications. - 0956-7976 .- 1467-9280. ; 9:3, s. 183-189
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In the first twin study of the old-old, individuals 80 years old and older, we examined the relationship between general and specific cognitive abilities from a genetic perspective. That is, we examined the extent to which genetic and environmental factors influence major group factors of cognitive abilities, independent of general cognitive ability. As part of the OctoTwin project in Sweden, general and specific cognitive abilities were assessed in 52 monozygotic and 65 same-sex dizygotic twin pairs 80 years old and older using a battery of seven tests that assess verbal, spatial, speed-of-processing, and memory performance. Results suggest that genetic effects associated with general cognitive ability (g) account for the correlation between g and verbal, spatial, and speed-of-processing abilities. No genetic influences were found for these specific cognitive abilities separate from g. In contrast, memory ability appears to be more distinct genetically from g than are other cognitive abilities. Comparison with younger samples suggests that cognitive abilities relating to speed of processing may be genetically dedifferentiated in the old-old.
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