| 31. |
- Wagner, Helene, et al.
(författare)
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Heritability of impaired balance : a nationwide cohort study in twins
- 2009
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Ingår i: Osteoporosis International. - : Springer Science and Business Media LLC. - 0937-941X .- 1433-2965. ; 20:4, s. 577-583
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Tidskriftsartikel (refereegranskat)abstract
- In this large population-based twin study, a self-estimated impaired balance, an important risk factor for osteoporotic fractures, had a modest heritability of 0.27. Individual-specific environmental influences seem to be the dominating cause for impaired balance. INTRODUCTION: The principal causal components of an osteoporotic fracture are falls and weakened bone strength. While bone strength has a strong genetic origin, the heritable influences on impaired balance that contribute to the risk of injurious falls at older age are uncertain. METHODS: To evaluate the heritability and environmental influence on self-reported impaired balance in older men and women, we used data from a sample of 22,998 Swedish twins, 55 to 99 years of age. RESULTS: An impaired balance was reported by 2,890 (12.3%) of the twins. The tetrachoric correlation for impaired balance was only slightly lower for like-sex dizygotic twins (0.31) compared to monozygotic twins (0.36). These correlations indicate a modest familial (genetic and shared environmental) influence. Model fitting results indicate that the age- and sex-adjusted heritability for impaired balance was 0.27 (95%CI = 0.01-0.45). Individual-specific environmental influences differed only slightly by sex and age. CONCLUSION: These results imply that a self-reported impaired balance, an independent risk factor for osteoporotic fractures, has a modestly heritable etiology in older subjects. Our observation can partly explain the previously observed modest heritability for osteoporotic fractures even though there is a high heritability for bone mineral density.
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| 33. |
- Åberg, Maria A I, 1972, et al.
(författare)
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Cardiovascular fitness is associated with cognition in young adulthood.
- 2009
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490.
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Tidskriftsartikel (refereegranskat)abstract
- During early adulthood, a phase in which the central nervous system displays considerable plasticity and in which important cognitive traits are shaped, the effects of exercise on cognition remain poorly understood. We performed a cohort study of all Swedish men born in 1950 through 1976 who were enlisted for military service at age 18 (N = 1,221,727). Of these, 268,496 were full-sibling pairs, 3,147 twin pairs, and 1,432 monozygotic twin pairs. Physical fitness and intelligence performance data were collected during conscription examinations and linked with other national databases for information on school achievement, socioeconomic status, and sibship. Relationships between cardiovascular fitness and intelligence at age 18 were evaluated by linear models in the total cohort and in subgroups of full-sibling pairs and twin pairs. Cardiovascular fitness, as measured by ergometer cycling, positively associated with intelligence after adjusting for relevant confounders (regression coefficient b = 0.172; 95% CI, 0.168-0.176). Similar results were obtained within monozygotic twin pairs. In contrast, muscle strength was not associated with cognitive performance. Cross-twin cross-trait analyses showed that the associations were primarily explained by individual specific, non-shared environmental influences (>/=80%), whereas heritability explained <15% of covariation. Cardiovascular fitness changes between age 15 and 18 y predicted cognitive performance at 18 y. Cox proportional-hazards models showed that cardiovascular fitness at age 18 y predicted educational achievements later in life. These data substantiate that physical exercise could be an important instrument for public health initiatives to optimize educational achievements, cognitive performance, as well as disease prevention at the society level.
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