Genetic effects on mobility, obesity and their association in older female twins

Nowadays it is common that men and women gain weight during their adulthood, arriving to older ages with excessive body weight or obesity. This may potentially have adverse consequences on health in late life, as for example, it can lead to higher difficulties to move in everyday life and eventually to earlier disability. Many studies have shown that in older population obesity and mobility problems are hand-by-hand. The main aim of the present investigation was to elucidate the extent to which this relation between mobility and obesity could be explained by common genetic and environmental influences in older women.This research utilized data from 434 Finnish twin sisters gathered during the 29 years (from 1975 to 2004), participating in the Finnish Twin Cohort and the Finnish Twin Study on Aging. This longitudinal data on obesity and mobility were analyzed utilizing complex mathematical modeling techniques that allowed estimating the contribution of genes and environment to population variability in the traits under study.The most important results indicated firstly that the genetic contribution to obesity increased with age from adulthood onwards. Analyses confirmed also that among community-living older women, there was an inverse association between obesity and mobility phenotypes that was mostly due to the genetic influences common to both traits. Women that were more genetically predisposed to gain body weight also showed poorer mobility in older age.The data from this study offer a new perspective to the study of the relation between mobility and obesity. Up to present, it was commonly known that little physical activity or bad eating habits could lead to adult and older persons to develop higher body weight along higher mobility problems. The results of this research indicated that the individual genetic background also have an important role in this mechanism. Genes controlling predisposition to obesity can be expressed progressively during adulthood and contribute to make some persons more vulnerable to difficulties in mobility at older ages. Therefore, the genetic influences predisposing to obesity in middle age also increase the risk for poorer mobility later in life.Some persons may be prone to gain weight and poorer mobility because of their genetic predisposition. In future, it may be possible to know whether a persons is on risk of obesity and mobility disability because of their genes. However, while the genetic liability on the mechanism is been investigated and specific genes are detected, individual screening and modification of non-genetic factors such as physical activity habits and diet remains the best approach to preserve or enhance mobility. For this reason it is recommended that older women engage healthy habits on diet and physical activity. Finding ways to promote physical activity and good nutrition among older people may be the most feasible approach for preventing obesity and mobility loss.