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- Jansson, M, et al.
(författare)
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Gender differences in heritability of depressive symptoms in the elderly
- 2004
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Ingår i: PSYCHOLOGICAL MEDICINE. - 0033-2917 .- 1469-8978. ; 34:3, s. 471-479
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The present study aimed to investigate the relative importance of genetic and environmental influences on depressive symptoms in the elderly. METHOD: Depressive symptoms were assessed through the Center for Epidemiological Studies-Depression (CES-D) scale. The CES-D scale was administered to 959 twin pairs (123 female MZs, 90 male MZs, 207 same-sex female DZs, 109 same-sex male DZs and 430 opposite-sex DZs) aged 50 years or older (mean age 72 years). A dichotomous depressed state variable was constructed based on CES-D cut-offs and self-reported use of antidepressant medication. Structural equation models were fitted to the data to dissect genetic and environmental variance components. RESULTS: The sex-specific heritability estimates for depressive symptoms were 14% for males and 29% for females and 23% when constrained to be equal for men and women. The prevalence of clinically significant depressive symptoms was 16% for men and 24% for women. Heritability estimates for the dichotomous depressed state measure were 7% for males and 49% for females in the full model and 33% when constrained to be equal. CONCLUSION: Our results suggest that depressive symptoms in the elderly are moderately heritable, with a higher heritability for women than men, although differences in heritability estimates were not statistically significant.
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| 2. |
- Gatz, M, et al.
(författare)
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Accounting for the relationship between low education and dementia: a twin study.
- 2007
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Ingår i: Physiol Behav. ; , s. 232-237
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Tidskriftsartikel (refereegranskat)abstract
- We evaluated whether the association between low education and greater risk of dementia is explained by genetic influences, using three different types of analyses. The HARMONY study (Swedish for "health" (Hälsa), "genes" (ARv), "environment" (Miljö), "and" (Och), and "new" (NY)) includes members of the Swedish Twin Registry who were aged 65 and older and alive in 1998, and who were screened and clinically assessed for dementia. There were 394 cases with dementia and 7786 unrelated controls. Analyses included co-twin control, tests for association between education and a measured genotype, and bivariate twin modeling. Low education was a significant risk factor for dementia both in case-control analyses (odds ratio=1.77, 95% confidence interval 1.38 to 2.28) and co-twin control analyses with monozygotic twin pairs (odds ratio=3.17, 95% confidence interval 1.26 to 7.93). Apolipoprotein E genotype was not associated with education and did not account for the relationship between education and dementia. Bivariate twin modeling showed that the association between education and dementia was not mediated by genetic influences in common between education and dementia. The association was mediated by shared environmental influences that were related to both dementia and to education. Low education is confirmed as a risk factor for dementia. Findings from three different analytic approaches showed that genetic influences did not explain this association.
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| 9. |
- Pedersen, N.L, et al.
(författare)
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How heritable is Alzheimer's disease in late life? Findings in Swedish twins
- 2004
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Ingår i: Annals of neurology. - : Wiley. - 0364-5134 .- 1531-8249. ; 55:2, s. 180-185
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Tidskriftsartikel (refereegranskat)abstract
- Although genetic effects are known to be important for early onset Alzheimer's disease, little is known about the importance of genetic effects for late-onset disease. Furthermore, previous studies are based on prevalent cases. Our purpose was to characterize the relative importance of genetic and environmental factors for incident Alzheimer's disease late in life, and to test for differences in the importance of genetic effects at different ages. A cohort of 662 pairs of Swedish twins 52 to 98 years of age who were without symptoms of dementia was followed up for an average of 5 years. Incident dementia cases were detected through follow-up at 2 to 3-year intervals using either cognitive testing or telephone screening followed by dementia workups. A physician, psychologist, and nurse gave consensus diagnoses. During the follow-up period, 5.8% of the sample was diagnosed with Alzheimer's disease. Average age of onset was 83.9 years (standard deviation, 6.3). Of the 26 monozygotic pairs in which at least one twin developed Alzheimer's disease, 5 were concordant (probandwise concordance, 32.2%). The concordance rate for dizygotic pairs was 8.7% (2 of 44 pairs). Structural model fitting indicated that 48% of the variation in liability to Alzheimer's disease could be attributed to genetic variation. Estimates did not differ significantly between twins younger than age 80 years and those older than age 80 years at baseline. Although these genetic estimates for incident disease are lower than those for prevalent disease, the importance of genetic factors for liability to Alzheimer's disease is considerable even late in life.
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