Search results for "Twin study"
showing 10 items of 115 documents
A twin study on the heritability of walking ability among older women
2006
BACKGROUND This study examined the role of genetic and environmental factors explaining individual differences in women's walking ability in old age. METHODS A maximal walking speed test over 10 meters and a 6-minute walking endurance test were done under standard conditions among 92 monozygotic and 105 dizygotic pairs of twin sisters reared together, aged 63-75 years. RESULTS The mean maximum walking speed was 1.73 +/- 0.32 m/s and the mean distance covered in the 6-minute walking test was 525.6 +/- 77.3 m. Multivariate genetic modeling showed that a minor part of the variances in walking speed (16%, 95% confidence interval [CI]: 0%-54%) and endurance (20%, 95% CI: 0%-56%) were accounted f…
Body Fat and Mobility Are Explained by Common Genetic and Environmental Influences in Older Women
2008
In older adults, mobility limitations often coexist with overweight or obesity, suggesting that similar factors may underlie both traits. This study examined the extent to which genetic and environmental influences explain the association between adiposity and mobility in older women. Body fat percentage (bioimpedance test), walking speed over 10 m, and distance walked in a 6-min test were evaluated in 92 monozygotic (MZ) and 104 dizygotic (DZ) pairs of twin sisters reared together, aged 63-76 years. Genetic and environmental influences on each trait were estimated using age-adjusted multivariate genetic modeling. The analyses showed that the means (and s.d.) for body fat percentage, walkin…
Hearing as a Predictor of Falls and Postural Balance in Older Female Twins
2009
BACKGROUND: The purpose of the present study was to examine, first, whether hearing acuity predicts falls and whether the potential association is explained by postural balance and, second, to examine whether shared genetic or environmental effects underlie these associations. METHODS: Hearing was measured using a clinical audiometer as a part of the Finnish Twin Study on Aging in 103 monozygotic and 114 dizygotic female twin pairs aged 63-76 years. Postural balance was indicated as a center of pressure (COP) movement in semitandem stance, and participants filled in a fall-calendar daily for an average of 345 days after the baseline. RESULTS: Mean hearing acuity (better ear hearing threshol…
Genetic and environmental influences on hearing in older women.
2007
Background. This study examined the relative contribution of genetic and environmental effects on the air-conducted hearing threshold level (0.5‐4 kHz) and speech recognition threshold level of the better ear as well as self-reported hearing in older women. Methods. Hearing was measured as a part of the Finnish Twin Study on Aging in 103 monozygotic (MZ) and 114 dizygotic (DZ) female twin pairs aged 63‐76 years. Audiometric measured hearing was tested using standardized methods in soundproof conditions. Self-reported hearing was assessed by a structured question. Quantitative genetic modeling was used for data analyses. Results. No significant differences in age, exposure to noise, hearing-…
Genetic and environmental contribution to postural balance of older women in single and dual task situations
2005
Abstract The purpose of the present study was to examine the effect of a second task on postural balance and to determine the role of genetic influences on postural balance when dual tasking among 206 monozygotic and 227 dizygotic female twins, aged 63–76 years. Balance was measured as medio-lateral and antero-posterior velocity of the centre of pressure (COP) (mm/s) and velocity moment (mm2/s) while standing on a force platform. Doing an arithmetic task increased movement of the COP while the hand motor task had no effect on movement of the COP. The genetic contribution to balance in the single task situation was minor (14%, 95% confidence interval, CI: 11–35%) whereas in the dual task sit…
Contribution of genetic and environmental factors to individual differences in maximal walking speed with and without second task in older women
2005
Background. Among older people, distraction while walking may increase the risk of falls. Factors underlying individual differences in dual tasking are not fully understood. Our aim was to study the effect of a second task on maximal walking speed and to examine whether individual differences in walking speed measured with and without a second task are accounted for by genetic and environmental influences shared across tasks or specific to each task. Methods. The data were collected from the 101 monozygotic and 116 dizygotic twin pairs aged 63–76 years recruited from the Finnish Twin Cohort. Maximal walking speed (MWS) over 10 m was measured on a laboratory corridor and timed with photocell…
Genetic and Environmental Influence on Structural Strength of Weight-Bearing and Non-Weight-Bearing Bone: A Twin Study
2007
A bivariate genetic analysis among 217 older female twin pairs showed that, although the structural strength of tibia and radius are mainly regulated by same genetic and environmental factors, the tibia is more affected by environment. Introduction: The habitual loading environment of the bone may modulate the relative contribution of genetic and environmental factors to bone structure. The purpose of this study was to estimate the contribution of the common and site-specific genetic and environmental factors to interindividual variation in compressive structural strength of the weight-bearing tibia and non–weight-bearing radius. Materials and Methods: pQCT scans were obtained from both mem…
Heritability of refractive astigmatism: a population-based twin study among 63- to 75-year-old female twins.
2013
PURPOSE: To examine the heritability of refractive astigmatism in older women. METHODS: Astigmatism was measured with an autorefractor in 88 monozygotic and 82 dizygotic female twin pairs aged 63 to 75 years. The prevalence and distribution of astigmatism and polar values J0 and J45 were estimated by standard statistical methods. Bivariate maximum likelihood model fitting was used to estimate genetic and environmental variance components using information from both eyes. RESULTS: Mean astigmatism of the more astigmatic eye was 0.93 diopters (D; SD ±0.58). Astigmatism of at least 0.25 D, 0.5 D, 0.75 D, or 1.0 D in either eye was present in 99.7%, 88.5%, 66.5%, and 46.2% of cases, respectivel…
The analysis of 51 genes in DSM-IV combined type attention deficit hyperactivity disorder: association signals in DRD4, DAT1 and 16 other genes.
2006
Contains fulltext : 35205.pdf (Publisher’s version ) (Closed access) Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder, starting in early childhood and persisting into adulthood in the majority of cases. Family and twin studies have demonstrated the importance of genetic factors and candidate gene association studies have identified several loci that exert small but significant effects on ADHD. To provide further clarification of reported associations and identify novel associated genes, we examined 1,038 single-nucleotide polymorphisms (SNPs) spanning 51 candidate genes involved in the regulation of neurotransmitter pathways, particularly dopamine, nor…
Longitudinal changes in genetic and environmental influences on older women's walking ability
2009
This study examined the stability and change over time in genetic and environmental influences on walking ability among older women. Maximal walking speed over 10 m and 6-min walking endurance test were measured under standard conditions at baseline and 3 years later. At both times, 63 monozygotic (MZ) and 67 dizygotic (DZ) twin pairs were measured for walking speed and 58 MZ and 56 DZ pairs for walking endurance. Participants were twin sisters reared together and aged 63-75 years at baseline. Genetic and environmental influences were examined using longitudinal genetic modelling. The results showed that walking speed was preserved from baseline to follow-up. Genetic influences on walking s…