Heritability Estimates For Functional Capacity Measures in an Elderly Swedish Twin Sample
Open Access
- Author:
- Mack, Holly Ann
- Graduate Program:
- Biobehavioral Health
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- September 29, 2003
- Committee Members:
- George Patrick Vogler, Committee Chair/Co-Chair
Gerald Eugene Mc Clearn, Committee Member
Stig Berg, Committee Member
Stephen A Petrill, Committee Member
David John Vandenbergh, Committee Member - Keywords:
- functional capacity
aging
genetics
lung function
body mass index
grip strength - Abstract:
- It is important to understand the genetic and environmental factors underlying the individual differences in functional capacity measures and how these influences change throughout aging since a decline in physical function has been a predictor of decreased mental ability, co-morbidities, and even mortality. The analyzed sample was comprised of subjects from an elderly twin study entitled ?The Origins of Variance in the Old-Old: Octogenarian Twins? (OCTO-Twin), which was drawn from the Swedish Twin Registry. Beginning in 1991, five waves of data were collected in two-year intervals on 149 monozygotic and 202 dizygotic same-sex twin pairs aged 80 or older. The contributions of environmental and genetic factors were examined separately for pulmonary function, body mass index (BMI), grip strength, and repeated chair stands at four measurement occasions. Multiple testing occasions allowed for the modeling of change in pulmonary function longitudinally, utilizing the genetic simplex model. The results indicated genetic stability throughout time for all four functional capacity measures with specific new genetic influences at each time point exerting a minimal effect. In general, the highest heritability estimates were for body mass index and the lowest heritability estimates were for the repeated chair stand task. The environment still had an impact on the total phenotypic variance for the four functional capacity measures analyzed. The substantial contribution of environmental influences was mainly accounted for by the environmental innovations at each time point.