The purpose of this investigation was to evaluate insulin-stimulated skeletal muscle glucose uptake in male Fischer 344 rats, age 6, 12, and 27 mo, fed either a sucrose (S: 66.6% sucrose, 17.6% protein, 6.4% fat) or sucr...The purpose of this investigation was to evaluate insulin-stimulated skeletal muscle glucose uptake in male Fischer 344 rats, age 6, 12, and 27 mo, fed either a sucrose (S: 66.6% sucrose, 17.6% protein, 6.4% fat) or sucrose-free (SF: 66.6% starch, 17.6% protein, 6.4% fat) diet for 3 mo. Skeletal muscle glucose uptake (Rg) in perfused hindlimbs was estimated from the uptake and subsequent phosphorylation of radiolabeled 2-deoxyglucose (2DG) in the gastrocnemius (GN), extensor digitorum longus (EDL), and soleus (SOL) muscles. Rat hindlimbs were perfused at a rate of 10 ml.min-1 with a modified Krebs Henseleit buffer containing bovine red blood cells (hematocrit: 40%) and 5.85 mmole.L-1 glucose along with 358 pmoles.L-1 followed by 3580 pmoles.L-1 insulin. There was no effect of diet on plasma glucose levels measured at weeks 1, 7, and 11 of the dietary period. A significant effect of age on estimated glucose uptake in the GN was demonstrated due primarily to greater uptake in the 27-mo compared to the 6-mo-old animals. This significant effect of age was not evident in the EDL or SOL, nor were there significant effects of diet in any muscle. These data suggest that insulin-stimulated glucose uptake in perfused hindlimbs is not attenuated with senescence or with the feeding of a sucrose diet for 3 months.
We have examined skeletal muscle for the presence of age-associated mitochondrial DNA (mtDNA) deletions from 16 rhesus monkeys (age range 6-27 years). All animals over 13 years of age contained potential mtDNA deletions,...We have examined skeletal muscle for the presence of age-associated mitochondrial DNA (mtDNA) deletions from 16 rhesus monkeys (age range 6-27 years). All animals over 13 years of age contained potential mtDNA deletions, whereas the presence of deletions was greatly reduced or absent in younger animals. The specific deletion patterns varied from individual to individual. Numerous mtDNA deletions accumulate with age in skeletal muscle from a nonhuman primate, indicating that the rhesus monkey may provide an excellent animal model to study mtDNA deletions. Further, the existence of multiple mtDNA deletions supports the possibility that they may contribute to geriatric muscular deficits, which are nearly universal in occurrence yet poorly understood.
Muscle weakness in the elderly is prevalent and morbid, closely linked to the frailty, functional decline, immobility, falls, and injuries in this population. The marked decrease in skeletal muscle strength and size with...Muscle weakness in the elderly is prevalent and morbid, closely linked to the frailty, functional decline, immobility, falls, and injuries in this population. The marked decrease in skeletal muscle strength and size with aging is a multifactorial syndrome which may be attributable in part to: (a) biological changes of aging itself; (b) the accumulation of acute and chronic diseases; (c) the assumption of a sedentary life style, and (d) selective or generalized nutritional inadequacies. Inactivity and undernutrition are potentially at least partially reversible with appropriate interventions, and therefore the delineation of the attributable risk of these two factors to the muscle weakness of aging is a critical research goal. Similarly, identification of appropriate modalities of physical activity and nutrition which have positive effects on muscle physiology in the aged is the focus of major investigations currently.
The effects of three different visual inputs (eyes open, eyes closed, and inaccurate) while standing on an unstable surface (respectively, UEO, UEC, UI) were compared in a group of healthy elderly community dwellers (N =...The effects of three different visual inputs (eyes open, eyes closed, and inaccurate) while standing on an unstable surface (respectively, UEO, UEC, UI) were compared in a group of healthy elderly community dwellers (N = 239; mean age 76) and young (N = 34; mean age 34) adults. Subjects with medical factors known to affect balance were excluded. Body sway and loss of balance measured dynamic force platform (EquiTest, NeuroCom International). Visual and somatosensory inputs were rendered inaccurate through tilting of the standing surface and/or the visual surround proportional to the subject's angle of sway (sway-referencing). The elderly group had significantly more difficulty balancing during UEC and UI, and a larger proportion lost their balance during UI. These findings are compared to those of other dynamic posturography studies in which sensory inputs were controlled. Issues of age, frailty, screening, and test protocol are addressed in order to account for differences in results among studies.
As members of our society live longer, a greater percentage of the population will be older. These demographic changes will stress our social and medical delivery system, unless interventions can alter the course leading...As members of our society live longer, a greater percentage of the population will be older. These demographic changes will stress our social and medical delivery system, unless interventions can alter the course leading to frailty. Maximal aerobic power decreases with age, due to a decrease in cardiac output, and is exacerbated by cardiovascular disease. Asymptomatic aging does not reduce cardiovascular function to an extent that would lead to loss of function. Metabolism, endurance, and contraction velocity and muscle strength remain relatively high until 40, 50, and 60 years of age, respectively. After age 60, there are dramatic decreases (approximately 10% per year) which lead to loss of function and independence. The loss of muscle function leads to an increase in the likelihood of falls (approximately 4-fold). Exercise programs utilizing "aerobic" exercise activities do not lead to an increase in muscle function, whereas programs designed specifically for muscle can increase function and, presumably, reduce the risk of falls and injuries.
Older adults frequently encounter difficulties performing daily living activities. Often times these difficulties arise because environmental demands create barriers which hinder task performance. Currently, there is lit...Older adults frequently encounter difficulties performing daily living activities. Often times these difficulties arise because environmental demands create barriers which hinder task performance. Currently, there is little empirical data that relate environmental demands to functional capabilities of older adults. The concepts and methods of Human Factors Engineering can be used to accomplish this goal. Human Factors views task performance within a systems context and maintains that successful task performance is dependent on a match between task demands and human capabilities. This article will discuss how Human Factors methodologies can be used to analyze problems encountered by older adults performing routine activities. Data from a study concerned with identifying physiological demands associated with personal and instrumental activities of daily living will be used to demonstrate the utility of using this approach.
Findings from a decade of research on physical frailty in diverse elderly populations are summarized and integrated. While much of the literature focuses on the physical and functional consequences of chronic and acute i...Findings from a decade of research on physical frailty in diverse elderly populations are summarized and integrated. While much of the literature focuses on the physical and functional consequences of chronic and acute illness, we emphasize the psychosocial and behavioral aspects of physical frailty. The underlying assumption of our approach is that the psychological representation of illness and disability, as well as the social contexts in which they occur, are important determinants of their impact on patients and family members. We focus on both patients and their primary support persons and on the comparative analysis of different disabling conditions. A patient and family caregiver impact model is used to summarize major findings of our research program and to make recommendations for intervention research.
Age-related changes in functional status can be summarized by active life expectancy (ALE) measures. ALE is useful in assessing efforts to improve function and in determining a population's service needs. ALE disaggregat...Age-related changes in functional status can be summarized by active life expectancy (ALE) measures. ALE is useful in assessing efforts to improve function and in determining a population's service needs. ALE disaggregates total life expectancy (TLE) into components representing degree and type of impairment. We illustrate the calculation of two ALE measures and their relations to health inputs and service use. First, scores are calculated from 27 measures of function for persons 65 and over, as reported in the National Long Term Care Survey (NLTCS). The scores are then used to calculate the two ALE measures. Results are compared to ALE calculated from the 1982, 1984, and 1989 NLTCS.
The purpose of this study was to document prevalence, identify leading indicators, and develop and assess prediction models for nursing home resident outcomes (death, discharge home). New residents (N = 647) in eight nur...The purpose of this study was to document prevalence, identify leading indicators, and develop and assess prediction models for nursing home resident outcomes (death, discharge home). New residents (N = 647) in eight nursing homes were evaluated on admission and 3 and 6 months later. Predictor variables tested included 14 health status variables, 5 demographic variables, and 6 other resident and nursing home variables. A cancer diagnosis was the most important risk factor for death at 3 months (OR = 8.0) and 6 months (OR = 10.8). A first nursing home admission was the most important risk factor for discharge to home at 3 months (OR = 9.5) and 6 months (OR = 13.9). Not having a dementia diagnosis was the second most important risk factor for discharge to home at 3 months (OR = 5.8) and 6 months (OR = 4.2). All prediction models demonstrated useful potential for clinical application.
The influence of premorbid psychosocial factors on physical function and institutionalization 6 weeks after hospital discharge was studied in elderly stroke patients. The predictor variables of interest were social netwo...The influence of premorbid psychosocial factors on physical function and institutionalization 6 weeks after hospital discharge was studied in elderly stroke patients. The predictor variables of interest were social networks, availability of social support, pre-stroke depression (CES-D), and religiousness. The data were obtained from a prospective longitudinal study based on 2,812 noninstitutionalized individuals aged 65 years and older living in New Haven, Connecticut. Incident stroke cases from this study were followed for post-stroke outcomes. Results from 87 survivors indicated that larger social networks were associated with fewer limitations in physical function, controlling for relevant health and sociodemographic conditions. Larger networks were also associated with a lower risk of institutionalization (p < .05). None of the other psychosocial factors assessed appeared to be related to these outcomes.
The factors associated with driving cessation, number of miles driven, and changes in mileage were assessed in a community-living elderly population. A driving survey was administered in 1989 to surviving members of the...The factors associated with driving cessation, number of miles driven, and changes in mileage were assessed in a community-living elderly population. A driving survey was administered in 1989 to surviving members of the New Haven EPESE cohort. Of 1,331 respondents, 456 had driven and 139 had stopped driving between 1983 and 1989. Independent predictors of driving cessation from a multiple logistic regression model included higher age, lower income, not working, neurologic disease, cataracts, lower physical activity level, and functional disability. These risk factors were combined to assess their ability to predict driving cessation. If no factors were present, no subjects stopped driving; if one or two factors were present, 17 percent stopped; if three or more factors were present, 49 percent stopped. Along with the expected medical factors, physical activity level and social and economic factors contributed to driving cessation. High mileage drivers tended to be younger, active males who still worked. Increasing age and disability were associated with mileage reduction compared to five years earlier.
This study assessed the relationships between six different types of social support and five measures of caregiving burden. Two questions were addressed: Are all types of social support equally associated with burden, an...This study assessed the relationships between six different types of social support and five measures of caregiving burden. Two questions were addressed: Are all types of social support equally associated with burden, and do the same types of support correlate with different types of burden? Family caregivers (N = 217) to frail elders composed the sample. Multiple regression analyses demonstrated that all types of social support for caregivers of frail elders are not equal. Engaging in social interaction for fun and recreation appears to be the most important in diminishing the burden of caregiving. These findings are instructive both theoretically and clinically. The theoretical import of greater social participation under a condition of chronic stress is discussed. Further, interventions that focus on caregivers regularly experiencing pleasant activity with friends and other family would seem to go a long way toward managing the burden of caregiving.
The purpose of this study was to attempt to explain why race differences emerge in examinations of life satisfaction among older adults retired from the work force. A conceptual model was developed and tested with data p...The purpose of this study was to attempt to explain why race differences emerge in examinations of life satisfaction among older adults retired from the work force. A conceptual model was developed and tested with data provided by 1,156 older Black and White individuals. The findings from this nationwide survey reveal that older Blacks have lower levels of life satisfaction than elderly Whites and that these differences may be attributed to the interplay between past aspirations and plans (as reflected by educational attainment and economic retirement plans) and present financial circumstances (as assessed by current financial strain and economic dependence on family members).
This research introduces the Reminiscence Functions Scale (RFS), a 43-item questionnaire that can be used to assess reminiscence functions over the lifecourse. Adults (710) ranging in age from 17 to 91 (mean age = 45.76...This research introduces the Reminiscence Functions Scale (RFS), a 43-item questionnaire that can be used to assess reminiscence functions over the lifecourse. Adults (710) ranging in age from 17 to 91 (mean age = 45.76 years) completed a 54-item Reminiscence Functions Scale-prototype measure, the results of which were submitted to a principal components analysis. Results indicated the viability of a 43-item, 7-factor solution with good reliability. Factors were labeled: Boredom Reduction, Death Preparation, Identity/Problem-Solving, Conversation, Intimacy Maintenance, Bitterness Revival, and Teach/Inform. A separate validity study demonstrated the predictive validity of the RFS. Directions for future research are discussed.