Most gerontological research is conducted using inbred strains of animals in an attempt to maximize phenotypic uniformity within experiments and thus increase the experimenter's statistical power to detect treatment effe...Most gerontological research is conducted using inbred strains of animals in an attempt to maximize phenotypic uniformity within experiments and thus increase the experimenter's statistical power to detect treatment effects. However, for a wide range of phenotypic traits, F1 hybrids between inbred strains are considerably less variable than the parental inbred strains themselves. Therefore, the use of F1 hybrids is preferable for many research applications. In this article, we discuss the sources of phenotypic variability and explain why F1 hybrids are often less variable than inbred strains; we review the empirical literature illustrating the large range of species and traits for which this is true; and finally we suggest how this finding suggests that F1 hybrids may often be superior animal models for studying the aging process and how to manipulate it.
BACKGROUND: The objective of the study was to identify clinical characteristics associated with depressive symptoms in late life so that screening could focus on elderly patients most likely to benefit from further evalu...BACKGROUND: The objective of the study was to identify clinical characteristics associated with depressive symptoms in late life so that screening could focus on elderly patients most likely to benefit from further evaluation. METHODS: We used cross-sectional screening for significant symptoms of depression using the Center for Epidemiologic Studies Depression scale and identification of patients' clinical characteristics from patient interviews and a computerized medical record. The setting was an academic primary care group practice at an urban ambulatory care center. Participants were 1,633 consecutively consenting patients aged 60 and older who visited the center between January and August 1991. Mean age was 70 years; 72% were women, 32% were White, 47% had less than 8 years of education, and 7% had no health insurance. RESULTS: There were 251 (15%) patients with significant symptoms of depression. Antidepressants were prescribed to 1 in 7 patients with such symptoms, with amitriptyline being the most commonly prescribed. Bivariate analyses indicated that patients with significant symptoms of depression were more likely to be White, female, without health insurance, and were more likely to have probable alcoholism, mild cognitive loss, and to receive narcotics, histamine H2 antagonists, and/or benzodiazepines. Depressive symptoms were not significantly correlated with age, education, income, or chronic medical conditions. CONCLUSIONS: Significant symptoms of depression were common and correlated with several readily available clinical variables. However, these variables lack sufficient discriminatory power to allow for the selective screening of elderly patients most likely to suffer from symptoms of depression. Thus, formal screening for depression among all elderly patients in primary care may be necessary to improve the recognition of this morbid illness.
This study describes differences between young-old (ages 60-74) and old-old (ages 75-90) parents' concerns regarding assistance provided by adult children. Old-old parents expressed more concern regarding amounts of help...This study describes differences between young-old (ages 60-74) and old-old (ages 75-90) parents' concerns regarding assistance provided by adult children. Old-old parents expressed more concern regarding amounts of help than did younger parents; there were no age differences in levels of concern regarding help outcomes. The percentage of children receiving parents' help and reliance on formal services predicted level of concern regarding help outcomes for the young-old parents, but not the old-old parents. Familism values and the extent of help received predicted level of concern regarding help amounts for the old-old parents, but not for younger parents. Implications for interventions to minimize parents' concerns and for further study of family assistance to the older people are discussed.
Age and education are known to be independently associated with MMSE score. This study addressed the relationship of principal lifetime occupations, which are related to both age and education, with MMSE scores in 524 co...Age and education are known to be independently associated with MMSE score. This study addressed the relationship of principal lifetime occupations, which are related to both age and education, with MMSE scores in 524 community-dwelling elders aged 70 and older. The data suggest that principal lifetime occupations are correlated with MMSE scores independently of the effect of age and education. As an example, formers have an average MMSE score 2.33 points lower than white-collar workers in a multiple linear regression analysis (95% C.I. 0.46-4.21), even after adjustment for age, education, and financial dissatisfaction.
The use of a cross-sectional sample of nursing home residents rather than a sample of admissions to estimate admission characteristics carries a potential bias. The purpose of this study was to fill this void by comparin...The use of a cross-sectional sample of nursing home residents rather than a sample of admissions to estimate admission characteristics carries a potential bias. The purpose of this study was to fill this void by comparing abstracted records data for an admissions cohort (n = 1,118) and a residents cohort (n = 830) residing in the same nursing homes. Compared to residents, admissions were significantly more dependent in their ability to get around and to dress themselves, received more clinical services, and had a higher rate of medication use. Over a 12-month period, admissions had a fivefold greater likelihood of being discharged to community, but about the same mortality rate as residents. Within both groups, those discharged to the community as well as those who died had expenditures that were almost twice as high as those of their counterparts who remained alive in the nursing home.
Do older people tend to exaggerate their health problems? Or do they downplay them? Do such tendencies change as people age? Are they a function of cohort membership? Or are differences in health perceptions among elderl...Do older people tend to exaggerate their health problems? Or do they downplay them? Do such tendencies change as people age? Are they a function of cohort membership? Or are differences in health perceptions among elderly people due to differences in survivorship within the elderly cohorts? These questions are examined with longitudinal data from the Yale Health and Aging Project, a stratified probability sample of elderly persons in New Haven, Connecticut. Complete health assessments are available for 2,583 community residents 65 and older in 1982, and complete follow-up date are available for 1,319 respondents in 1988. Multivariate regressions of self-assessed health on concurrent 1982 and 1988 objective health status and longitudinal analysis of residual values from these equations show that: (a) older survey respondents gave disproportionately positive health assessments, and (b) processes of aging, selective survivorship, and cohort differences all appear to play a role in creating this pattern.
Changes in the absolute and relative size of the elderly population since 1960 are decomposed into the underlying demographic components for metropolitan and nonmetropolitan areas and for subregions of the United States....Changes in the absolute and relative size of the elderly population since 1960 are decomposed into the underlying demographic components for metropolitan and nonmetropolitan areas and for subregions of the United States. Specifically, we examine the components of net migration and natural increase for those aged 0-64 and those 65 or older. Generally, the natural increase component for those 65 and over has increased since 1960, whereas that for those under 65 has declined. Metropolitan areas have consistently lost, and nonmetropolitan areas gained elderly migrants. Trends in elderly population change are far from uniform across nonmetropolitan America. In general, the "aging" of the nonmetropolitan population was predominantly due to elderly migration during the 1970-80 decade, and to the loss of young people both before and afterward. Recent trends give little support for the view that the 1970s was the beginning of a new phase of deconcentrated settlement, even for elderly persons.
This study examined the relationships among stress, social support, and depressive symptoms with data provided by a large representative sample (N = 2,721) of older adults who live in the People's Republic of China. Many...This study examined the relationships among stress, social support, and depressive symptoms with data provided by a large representative sample (N = 2,721) of older adults who live in the People's Republic of China. Many Western investigators believe that elderly people respond to stressful experiences by mobilizing assistance from their significant others. However, recent American studies suggest that this may not always be true, and that when certain stressors arise, older adults may actually receive less support from significant others. The purpose of our study was to evaluate these competing views in a culturally diverse setting. The findings reveal that both perspectives have something to offer and that financial strain (i.e., one kind of stressor) may increase some kinds of assistance (i.e., economic support) at the same time that it erodes other types of support (e.g., emotional support).
Age-cohort differences for seven tests from the Halstead-Reitan Neuropsychological Battery, for overall performance on the Impairment Index, and for a multivariate composite of the seven scores, were examined for 427 sub...Age-cohort differences for seven tests from the Halstead-Reitan Neuropsychological Battery, for overall performance on the Impairment Index, and for a multivariate composite of the seven scores, were examined for 427 subjects falling into six age groups (15-24, 25-34, 35-44, 45-54, 55-64, and 65 years and over). Univariate and multivariate-discriminant analyses were performed. Poorer performance was observed across age-cohorts (linear trend) for all tests and the Impairment Index. A very modest Age-Cohort (linear trend) x Gender interaction was observed only for the Category Test. Decline in Category Test performance across age-cohorts was more pronounced for women than for men. For women, the best discrimination among age groups was observed for the Category Test. For men, Tactile Performance Localization Test discriminated best. The poorest discrimination among age groups was seen for Finger-Tapping for men and Tactile Performance Test--Total (time score) for women. Results were consistent with a model of specific nested within general decline. Although linear-trend across age groups was observed for all tests, the strongest discriminations were associated with neuropsychological tests of abstraction and complex problem-solving performance.
We examined the effects of selected health conditions and sensory functions, socioeconomic status, age, and education on cognitive functioning in 3,974 community-dwelling individuals aged 65-84 years. Logistic regression...We examined the effects of selected health conditions and sensory functions, socioeconomic status, age, and education on cognitive functioning in 3,974 community-dwelling individuals aged 65-84 years. Logistic regression analysis was used to examine the independent and joint effects of these variables on borderline (Mini-Mental State Exam [MMSE] of 22-25) and poor (MMSE of < or = 21) functioning relative to adequate functioning (MMSE of 26-30). The effect of age and of education on MMSE performance was relatively stable, even after adjusting for age- and education-related health conditions and sensory impairments that also influenced level of cognitive functioning. These conditions included poor vision, Parkinson's disease, diabetes, depression, stroke (in 65-74-year-olds), and low socioeconomic status (in 75-84-year-olds). Education did not modify the effect of these variables on MMSE performance. Additional studies elucidating further the mechanisms that relate these sociodemographic factors to cognitive performance are warranted, as are studies of the relationship between these factors and the incidence of cognitive impairment.
Reaction time (RT) data in two tasks from a total of 784 adults between 18 and 87 years of age were analyzed to determine the relation between age and parameters of the intra-individual RT distribution. Although the abso...Reaction time (RT) data in two tasks from a total of 784 adults between 18 and 87 years of age were analyzed to determine the relation between age and parameters of the intra-individual RT distribution. Although the absolute magnitude of the age differences was greatest for the slowest RTs in each individual's RT distribution, there was little or no independent age-related variance in the slowest RTs after controlling for the variance in the fastest RTs. Furthermore, the relation between RT and measures of motor speed, perceptual speed, working memory, and accuracy in several cognitive tasks was of nearly the same magnitude when only the fastest responses were considered as when both fast and slow responses were considered. These results imply that age-related slowing is associated with a shift (and expansion) in the entire RT distribution, and is not attributable to a selective influence on the individual's slowest responses.
BACKGROUND: There has been disagreement over the significance of bacteriuria in nursing home residents. METHODS: During an 18-month period, the risks and consequences of bacteriuria (BU) in 195 residents of a skilled nur...BACKGROUND: There has been disagreement over the significance of bacteriuria in nursing home residents. METHODS: During an 18-month period, the risks and consequences of bacteriuria (BU) in 195 residents of a skilled nursing facility without indwelling catheters were examined. Clinical and epidemiologic data and urine for culture were collected every 2 weeks to identify risk factors, symptoms, and occurrences of BU. A mean of 23 cultures per resident was collected. RESULTS: Forty-three percent of the study population (35% of men; 47% of women) had "persistent BU" defined as > 10(5) cfu/ml of urine on > 25% of an individual's collected cultures. Women with persistent BU more frequently were incontinent of bowel and bladder (OR 5.3, 6.3, respectively), more likely to be functionally disabled (OR 3.2), to carry a diagnosis of dementia (OR 2.4), and less likely to have suffered a stroke (OR 0.40). Cancer (OR 6.5) was the only risk factor for persistent BU in men. The number of antibiotic courses prescribed, frequency of hospitalizations, and mortality rates were not significantly different between the two BU groups in either men or women. CONCLUSIONS: Persistent BU is common in nursing home residents. The association of bowel and bladder incontinence and functional disability with persistent bacteriuria suggests that treatment or prevention of these risk factors may prevent or decrease the incidence of bacteriuria. There was no evidence of significant adverse outcomes resulting directly from the bacteriuric state. Higher mortality in the bacteriuric group was the result of underlying functional debility and severity of illness rather than the presence or persistence of BU.
BACKGROUND: Little is known about the relationships of visual impairment and hearing impairments to physical disability. The purpose of this work is to determine if persons 70 years of age and over with these impairments...BACKGROUND: Little is known about the relationships of visual impairment and hearing impairments to physical disability. The purpose of this work is to determine if persons 70 years of age and over with these impairments are at risk for increased disability in basic physical activities of daily living (ADLs) compared to persons without these impairments. METHODS: We used as our data source the baseline (1984) and the 1988 reinterview from the Longitudinal Study of Aging, a nationally representative survey of noninstitutionalized persons 70 years of age and older. To determine the relationships of visual impairment and hearing impairment to future four-year disability, we used multiple variable modeling, controlling for demographic variables, selected chronic conditions, and baseline disability. RESULTS: Persons with visual impairment were 1.37 (95% CI:1.20-1.57) times more likely to have increased disability in ADLs than those without visual impairment. Hearing impairment was not independently related to increased ADL disability. CONCLUSIONS: Visual impairment by itself is an independent risk factor for future ADL disability. In light of the enlarging older population, maneuvers to ameliorate visual impairment may help to minimize the increase in numbers of disabled persons.
BACKGROUND: This study compared the occurrence of psychiatric symptoms in a large group of community-residing participants enrolled in an Alzheimer's disease patient registry who met clinical diagnostic criteria for Alzh...BACKGROUND: This study compared the occurrence of psychiatric symptoms in a large group of community-residing participants enrolled in an Alzheimer's disease patient registry who met clinical diagnostic criteria for Alzheimer's disease or multi-infarct dementia, as well as mixed Alzheimer's disease and multi-infarct dementia. METHODS: Psychiatric morbidity observed from a psychiatric examination of 514 patients with Alzheimer's disease, 135 patients with multi-infarct dementia, and 86 cases with mixed dementia was analyzed using analysis of variance comparing symptoms across groups and chi-square test for differences in frequency of occurrence. Associations between pairs of symptoms were also reported. RESULTS: The frequency of occurrence and patterns of psychiatric problems were similar in patients with Alzheimer's disease and multi-infarct dementia. Agitation was the most frequent symptom, followed by depression, apathy, and behavioral disorders. Patients with mixed dementia had significantly more psychopathology. CONCLUSION: This study demonstrated that significant psychopathology occurs in individuals with Alzheimer's disease or multi-infarct dementia. The high levels of symptoms in mixed dementia suggest that the two conditions have a synergistic effect on behavioral problems. The prevalence of multiple symptoms is higher than previously reported.
BACKGROUND: Associations between anthropometric measurements of fat patterning and risk factors for cardiovascular disease have been demonstrated in several populations composed predominantly of White, young or middle-ag...BACKGROUND: Associations between anthropometric measurements of fat patterning and risk factors for cardiovascular disease have been demonstrated in several populations composed predominantly of White, young or middle-aged adults. Fat pattern changes with aging and older adults tend to have a more central or abdominal fat distribution. Few investigators have focused on relationships of fat patterning with plasma lipids or blood pressure in older adults or in Blacks. METHODS: Body mass index (BMI), fat patterning, plasma lipids, and blood pressure were examined in participants of the Charleston Heart Study. Subjects included 216 White men, 95 Black men, 320 White women, and 155 Black women with a mean age of 72.7 years (range 61-106). RESULTS: In each of the four race and gender groups, BMI was inversely correlated with HDL cholesterol and positively correlated with hypertension. BMI tended to be positively associated with total cholesterol, although the relationships were not statistically significant. After controlling for the effects of BMI, age, smoking, and alcohol intake (using regression analysis), waist to hip ratio was associated with cholesterol levels in the White men and women and the Black men. In similar models, waist circumference in Black women was inversely associated with HDL. There were no significant relationships between waist to hip ratio and hypertension in any of the groups after controlling for BMI. CONCLUSION: In an elderly cohort, waist to hip ratio was associated with plasma lipids, but not with hypertension, when the effects of BMI were held constant.
BACKGROUND: The methods commonly employed in body composition study in elderly persons derive fat-free mass (FFM) by measures of total body water (TBW); these methods assume FFM hydration constant (TBW/FFM = 0.732). The...BACKGROUND: The methods commonly employed in body composition study in elderly persons derive fat-free mass (FFM) by measures of total body water (TBW); these methods assume FFM hydration constant (TBW/FFM = 0.732). The aim of our study was to verify the accuracy of the TBW method in FFM estimation and to study the variability of fat-free mass hydration (TBW/FFM) in healthy elderly subjects. METHODS: We assessed FFM in 27 healthy old subjects (76 +/- 7 yrs) by dual photon absorptiometry (DPA) and by TBW measured by 3H2O. Furthermore, to verify the accuracy in FFM estimation by our methods, we measured resting metabolic rate (RMR) by indirect calorimetry. RESULTS: FFM hydration was 71.9 +/- 4.9 (range 63.6-80.4%), a range larger than that reported by direct chemical analysis in adults. The FFM hydration measured in our subjects was not different from the 73.2 value currently used in healthy adults. FFM values derived by TBW (assuming TBW/FFM = 0.732) were not significantly different from FFM measured by DPA. We correlated FFM with resting metabolic rate and found a similar correlation between RMR and FFM-DPA (r = .89, p < .001) and FFM-TBW (r = .85, p < .001). CONCLUSIONS: Both methods employed in our study have proved to be accurate in estimating FFM in elderly persons; particularly, the value of 0.732 assigned to FFM hydration to derive fat-free mass in adults can be employed also in body composition study of the elderly.
BACKGROUND: The purpose of this study was to determine whether age is a predictor of sensitivity to the peripheral effects of insulin on carbohydrate metabolism independent of the potential influences of the level of sym...BACKGROUND: The purpose of this study was to determine whether age is a predictor of sensitivity to the peripheral effects of insulin on carbohydrate metabolism independent of the potential influences of the level of sympathetic nervous system (SNS) activity and blood pressure (BP). METHODS: In 60 human subjects (age range 19-78 years), insulin sensitivity, SI, was determined from glucose and insulin levels obtained during an intravenous glucose tolerance test, and plasma norepinephrine (NE) levels were measured to estimate SNS activity. RESULTS: There were age-associated increases in plasma NE level (r = .585; p < .001) and mean arterial BP (r = .516; p < .001), and an age-associated decline in SI (r = -.352; p = .04). However, in stepwise multiple regression analysis, body mass index (BMI) and mean arterial BP were the only independent predictors of SI, accounting for 43% of the variance in SI; age, plasma NE level, plasma epinephrine level, and fasting plasma glucose did not enter the model. Although these results suggest an age-associated decline in insulin sensitivity, this decline appears to be associated with BMI and mean arterial BP rather than aging per se. In addition, the age-associated increase in SNS activity was not found to be an independent predictor of insulin sensitivity. CONCLUSION: This study demonstrates that in addition to BMI, blood pressure should be considered as another confounding factor in studies of insulin sensitivity in human aging.
The heritability of human longevity was investigated in a sample of 218 pairs of monozygotic (MZ) and 382 pairs of like-sex dizygotic (DZ) Danish twin pairs born 1870-1880. Twin similarity for age at death was significan...The heritability of human longevity was investigated in a sample of 218 pairs of monozygotic (MZ) and 382 pairs of like-sex dizygotic (DZ) Danish twin pairs born 1870-1880. Twin similarity for age at death was significant for MZ twins but nonsignificant for DZ twins. The heritability (h2) of life span estimated from the best-fitting biometrical model was statistically significant but moderate in magnitude (h2 = .333 +/- .058). Heritability of longevity did not vary by gender, and the pattern of twin resemblance was more consistent with nonadditive as compared to additive genetic effects. In addition, evidence for a genetic association between premature and senescent deaths was observed. Although environmental factors accounted for a majority of the variance in life span, the relevant environmental factors appeared to be those that create differences rather than similarities among reared-together relatives. Findings are discussed in terms of their relevance for understanding the inheritance and evolution of human life span.
Vaccinations are often unsuccessful in preventing infection among elderly populations because of generally poor humoral immune responses. We have used tetanus toxoid (TT) antigen to stimulate in vitro anti-tetanus toxoid...Vaccinations are often unsuccessful in preventing infection among elderly populations because of generally poor humoral immune responses. We have used tetanus toxoid (TT) antigen to stimulate in vitro anti-tetanus toxoid antibody (anti-TT) synthesis and have found that lymphocytes from many healthy elderly individuals have a reduced production of anti-TT in vitro compared to young adults. This is associated with decreased numbers of B cells secreting anti-TT IgG and a decrease in the mean amount of anti-TT IgG produced per TT-specific B cell. In the present study we report that immunization results in a significant increase in serum titers in young adults for up to one year, whereas levels in old adults fall to baseline by 6 months. The number of B cells that secrete anti-TT IgG increases after immunizations in both young and old subjects, although the number in old subjects is significantly lower than in young subjects at all times except 6 months after. The mean amount of anti-TT produced per B cell (B-cell potency) is significantly lower for the old adults both before and at 6 and 12 months after booster. Immunization does not significantly change the mean amount of anti-TT produced per B cell for either age group. The decreased response to immunization with aging is associated with decreased numbers of specific Ab-secreting B cells and usually decreased potency of those B cells.
Male Wistar rats aged 6-26 months were obtained from the colony of The Gerontology Research Center of the National Institute on Aging, and pathological profiles were assessed. One hundred animals were sacrificed at 6, 12...Male Wistar rats aged 6-26 months were obtained from the colony of The Gerontology Research Center of the National Institute on Aging, and pathological profiles were assessed. One hundred animals were sacrificed at 6, 12, 18, 21, 24, and 26 months and used for cross-sectional determinations; also, 150 animals were followed longitudinally and sacrificed when clinical signs of moribundity appeared. Renal disease contributed the most common pathology observed in both studies (found in over 70% of the animals examined), with neoplasms a secondary problem (pituitary tumors were by far the most prevalent, with adenomas present in approximately 20% of the animals). This analysis represents the first complete pathological characterization of this commonly used rat model for aging research, and offers an opportunity for comparison with other rat strains.