Journal of Gerontology

Published by Gerontological Society of America
Print ISSN: 0022-1422
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Although simple reaction time (RT) to a tone showed a statistically significant increase between 18 and 93 years of age in a sample of 220 men and women, the amount of increase was slight, less than 2 msec/decade. Consequently, the appreciable slowing of more typical behavior with age does not seen attributable to some general process in the central nervous system as has been argued. This degree of stability found for simple RT with age, unexpected from the body of previous work, may reflect equivalence of age groups and use of optimal RT technique. In a second study eight old participants (73 to 84 years) matched on the optimal technique with eight young participants (18 to 24 years) were markedly slower with a long constant preparatory interval but not with elimination of timing cues. Together, the two studies show that simple high level of preparation was either easy of impossible to attain. Behavioral slowing with age can result from ineffective control processes.
 
To investigate further the age-related reduction in muscle protein synthesis activity found previously using a crude polyribosome/pH 5 system (Pluskal et al., 1984), a 0.5M KCI washing procedure was utilized to remove the nonribosomal factors from polyribosomes isolated from male Sprague-Dawley rats in the following age groups: young (1 to 2 months), mature (12 months), and aged (22 to 24 months). Using a common source of enriched elongation factor fraction from young animals, it was not possible to demonstrate any significant difference (p> .05) in protein synthesis between the 0.5M KCI-washed polyribosomes isolated from the various age groups. Using a cell-free system containing young salt washed polyribosomes stimulated by the addition of 0.5m KCI-wash fractions, however, it was shown that the mature and aged salt-wash fractions were less (p < .05) active than material from young animals. Thus, the observed decline in protein synthesis efficiency during aging may be attributed to a reduced capacity to promote initiation/ elongation by the nonribosomal salt wash fractions of muscle polyribosomes.
 
Because tacrine, a cognitive enhancing agent, was being considered for approval for use in Alzheimer's disease, its possible interaction with ethanol, a commonly used substance to which elderly individuals are generally more sensitive than younger individuals, was explored. For purposes of comparison, two other drugs, which have also been shown to improve memory in mice, at doses which had activity in a working memory paradigm, were evaluated for an interaction with ethanol. Ethanol-induced sedation in mice was increased by tacrine and decreased by physostigmine, whereas AIT-082 did not alter sedation. However, tacrine had no effect on body temperature or on ethanol-induced hypothermia. Neither tacrine nor physostigmine had any effect on the rate of ethanol elimination from the blood. As tacrine comes into clinical use in the treatment of Alzheimer's disease, adverse interactions with ethanol should be explored further
 
Active life expectancies (ALEs) were calculated using increment-decrement life table techniques for 10,000 Caucasian men and women from three geographic areas. This technique is more appropriate than the single decrement model originally used, and resulting ALE was substantially greater among initially independent men and women aged 65 years: from 9.3 for men and 10.6 for women to 11.3 to 13.0 for men and 15.5 to 17.1 for women. These increases may be attributable to factors other than the change of method, however, including the change in time from 1975 to 1982 and the change from one state to three communities. The sex differences suggest that the added years of life that women have enjoyed over men are neither solely added years of vigor nor solely added years of disability, but added years with the same mix of independence/dependence that the shorter-lived males experience. The age patterns suggest that at any age the future presents a relatively constant expectation of the total duration of dependency, and concordantly, as one ages, there is a relatively uniform decrease in the proportion of active life to remaining years.
 
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.
 
Epidermal cell renewal was assessed nonintrusively in normal human volunteers by monitoring the disappearance of a fluorescent marker dye, dansyl chloride, from the skin surface. In young adults, stratum corneum transit time was approximately 20 days, whereas in older adults this was lengthened by more than 10 days. Because the number of horny cell layers does not change with age, these data indicate that the increased stratum corneum transit time was a reflection of diminished epidermal cell proliferation. Additional analysis indicated that the decline in epidermal cell renewal may not occur at a constant rate throughout the adult lifespan but, instead, remains relatively constant in the younger years and then begins to drop dramatically after age 50. This suggests that a linear-spline model rather than a simple linear model may be more appropriate for analyzing these results.
 
We examined whole body leucine metabolism in healthy young and elderly adults while in the postabsorptive state and during an intravenous glucose administration at two rates. Leucine flux, incorporation into whole body protein, and oxidation were estimated from a continuous intravenous infusion of L-[1-l3C]leucine and determination of 13C enrichment in plasma leucine and expired air. Per unit of body weight, leucine flux and rates of incorporation into protein were similar in young and old men. Old women showed lower rates compared with young women. Rates were similar for both age groups when expressed per unit of total body water and/or of muscle protein mass. Intravenous glucose infusion (4 mg·kg−1min−1) reduced plasma leucine levels and flux similarly in both age groups. Thus, age-related differences in muscle mass and sensitivity of peripheral tissues to insulin-mediated glucose uptake and metabolism are not paralleled by alterations in whole body leucine kinetics in the postabsorptive state.
 
Tubulin, the protein of neurotubules, aids in the movement of other proteins and organelles within axons and may be involved in the pathogenesis of senile dementia in man. This led us to investigate the effect of age on the synthesis of tubulin and of total brain protein of mice. Brain slices from 5-, 12-, 18-, and 25 mo.-old mice were incubated with [14C] leucine. The slices were then homogenized and tubulin was precipitated from the 100,000g supernate by vinblastine. Protein synthesis was measured by [14C] leucine incorporation into hot trichloroacetic acid-insoluble protein and tubulin was quantitated by [3H] colchicine binding. The 4 age groups did not differ significantly in the relative specific activities of their total protein or of their tubulin. The content of the colchicine-binding protein (tubulin) also was not affected by age. These findings suggest that, at least in mice, aging does not significantly affect the rate of synthesis of brain protein or tubulin.
 
Aerobic capacity (VO2 max) and body fat were measured indoors and VO2 was measured at about 36 to 42°c in desert walks or runs in 69 adults aged 17 to 88 years. Eleven were athletic youths, and many of the older adults had participated in jogging programs. Body fat increased and VO2 max decreased with age, although there were notable exceptions. Rates of walking and running were planned to require about 40% of VO2 max. Midway in each walk VO2 (ml O2/horizontal m*kg) served as a measure of skill; skill was high in 10 of 11 youths who did many walks or runs. Each older adult did three walks; skill improved. In four groups with some persons aged 50 and older with body fat up to 40%, skill in their third walk matched that of youths. The least fit women and the least fit men did not attain that level of skill.
 
Although many workers have tested adrenal function in the elderly, few have studied the effect of aging on cortisol production rate or urinary free cortisol or 6 beta-hydroxycortisol excretion, and none have published comparisons of these variables between old people of defined health status and young people. We have measured cortisol production rate and the urinary excretion of free cortisol, 6 beta-hydroxycortisol, 17-hydroxycorticosteroids (Porter-Silber chromogens) and creatinine in elderly men and women screened by the SENIEUR protocol and in young men; 17-hydroxycorticosteroid and 6 beta-hydroxycortisol excretion were also measured in young women. The period of measurement was 24 h or, usually, 48 h. Only 6 beta-hydroxycortisol excretion was affected by aging; it was lower in the elderly men and women than in their younger counterparts. Urinary free cortisol excretion was lower in the elderly women than in the elderly men. There were no significant differences between groups in cortisol production rate or 17-hydroxycorticosteroid excretion. Excretion and (over the first 24 h) clearance of creatinine were lower in the old women than in the old men. The cortisol-related variables tended to be positively correlated with each other and with the relevant creatinine-related variables in the elderly subjects; over the first but not the second 24 h, most of the correlations were significant in the men and women combined. With the exception of 6 beta-hydroxycortisol, the data agree with measurements of plasma cortisol and the results of adrenal function tests in showing little change in hypothalamic-pituitary-adrenal function with aging in healthy people.
 
From a study of the neutral 17-ketosteroid excretion in the urinei of 260 persons (140 men and 120 women aged l8 to 90) Dr. Kowalewski demonstrates a progressive decrease in excretion of these compounds with advancing age and points out the magnitude of daily variations in the elimination of urinary steroids in the same individual
 
Indexes of dissimilarity were calculated for 18 standard metropolitan statistical areas in 1970 and 1980. The indexes measured the level of residential segregation of persons 65 and older, 65 to 74 and 75 and older. Results indicated a significantly higher level of segregation for persons 75 and older than persons 65 to 74 in both 1970 and 1980. The difference in the level of residential segregation between persons 65 to 74 and 75 and older significantly increased from 1970 to 1980. When measured as a single age group aged 65 and above, there was no significant change in the level of residential segregation from 1970 to 1980. This result indicates that failure to disaggregate the elderly population into two distinct age groups would have resulted in missing changes in the level and trend of residential segregation among the elderly population
 
Average absolute difference in age at death (in years) between two members of a monozygotic (MZ) twin pair, two members of a dizygotic (DZ) twin pair, and two randomly selected same-sex individuals. Bars indicate one standard error of the mean. The average for MZ twins is significantly smaller than the average for DZ twins (p < .001), but the DZ average is not significantly different from the average based upon randomly constituted pairs (p > .05).  
Characteristics of the Sample of Danish Twins Born 1870-1880
MZ and DZ Twin Resemblance for Age at Death as Measured by the Twin Intraclass Correlation (R) and Mean Absolute Difference (Diff)
Results of Fitting Biometrical Models to the Twin Data
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.
 
To describe the association between self-selected speeds of walking, and age, maximal aerobic power, and body size, 84 men aged 19 to 66 years were asked to walk at four self-selected paces, from rather slowly to as fast as possible. Speed of walking was measured over a 240-m indoor course. Maximal oxygen uptake was determined on a treadmill. The speed of walking was significantly slower in the oldest (55 to 66 years) compared with the youngest group (19 to 29 years) at the normal fast, and as fast as possible speeds. However, when age, weight, height, and fatness were held constant in a multiple regression model, VO2 max was significantly related to speed of walking at the three fastest walking paces. Age was not significantly related to speed of walking at any pace. Thus, this study indicated that the speed of self-selected walking paces was associated with maximal aerobic power independent of age.
 
Recent changes in the suicide rate of aged white males in America are considered in this study. It is shown that the trend in aged male suicide is closely similar, in the negative direction, to trends in aged income status. A multivariate model, incorporating social and economic variables in a dynamic manner, is formulated. The analysis of rates based upon the dynamic multivariate formulation shows that income status has exerted a significant, negative impact upon aged white male suicide over the period of the analysis. The social variables considered apparently have little or no significance with respect to the course of suicide over the period analyzed.
 
The effects of screening on breast cancer mortality, incidence, and prevalence were investigated using a general forecasting and simulation model. First, a biologically motivated model of disease incidence and mortality was fit to the breast cancer mortality experience of 15 U.S. White female birth cohorts followed for a 38-year period. The model assumed that breast cancer was the result of two different diseases. The first, or "premenopausal" disease, tends to have strong associations with the family history of disease and to be histologically more aggressive. The second, "postmenopausal" disease, occurs at more advanced ages, is apparently less strongly linked to family history, and is less aggressive with different histological characteristics (e.g., positive estrogen receptor status). Those results were used to forecast the effects of screening on the stage at diagnosis to simulate a screening program which reduced late-stage diagnoses by 50%. This produced large reductions in breast cancer mortality--an impact larger for disease associated with late age of onset.
 
Changes in the absolute and relative size of the elderly population within metropolitan and nonmetropolitan areas are decomposed into the underlying demographic components for three time periods: 1950 to 1960, 1960 to 1970, 1970 to 1975. Specifically, we examine the components of net migration and natural increase of those aged 0 to 64 and those 64 or older. Using published migration estimates for the U.S., this study demonstrates that elderly migration has represented an increasingly important component of the absolute growth of the elderly population within nonmetropolitan areas and a corresponding decline in large SMSAs. Although "aging-in-place" was a dominant component of change in he elderly percentage irrespective of residence, we show that the demographic components of the young also exercise an important and often overlooked effect on the aging process. Most prominent was the slowing of relative aging in remote nonmetropolitan areas, due largely to the post-1970 changeover from net outmigration to net inmigration of those less than 65 years of age.
 
One type of population redistribution is discussed in this paper. It is the migration of older people between metropolitan and nonmetropolitan locations as it has occurred over two decades. Net migration studies have documented the metropolitan-to-nonmetropolitan turnaround but have not been able to connect the origin with the destination of the individual migrants. Neither have they been able to examine the differences between interstate and intrastate migrants in this pattern. The dynamics of the process, therefore, has been left unexplored. The data used in this analysis came from the two most recent, available, 1-in-100 public use samples, one from the 1960 census and the other from the 1970 census. Only the records of persons aged 60 years and over in these samples were examined. The turnaround was again documented. It became clear, however, that interstate migration over the two decades came to dominate the pattern. What appeared from the marginals to be a turnaround among intrastate migrants resulted from decreased migration into metropolitan areas from nonmetropolitan locations. The metropolitan outflow did not change. PIP The migration of older people between metropolitan and nonmetropolitan areas in the United States over the past two decades is examined using data from the 1-in-100 Public Use Samples of the 1960 and 1970 censuses for people over 60 years of age. The predominance of interstate over intrastate migration is indicated by the analysis.
 
Fiber intake was estimated by 7-day diet record in community-dwelling men of the Baltimore Longitudinal Study of Aging. The mean intake of 845 men (age 20-103) was 3.82 +/- 0.03 g crude fiber/day which corresponds to approximately 15 g/day of dietary fiber. Fiber intake increased across the age span (slope = +0.022 +/- 0.003 g/yr, p less than .01). Longitudinal analysis of 380 men, each of whom provided 3-8 diet records over an average period of 8 yr, indicated that the increase in fiber intake occurred in each age group and was not the result of differential survival. Fiber intake was negatively correlated with body mass index. After clinical screening to eliminate variables which could independently influence coronary risk factors, multiple regression analyses including age and body mass index were conducted to examine the effect of fiber (adjusted for total calorie intake) on blood pressure, blood lipids, and glucose tolerance. For systolic and diastolic blood pressure, triglyceride, and fasting plasma glucose, higher fiber intake was associated with lower levels of the risk factors (p less than .05).
 
Analysis of county level elderly and nonelderly net migration data revealed that, overall, migration was of less importance in explaining changes in elderly population concentration between 1970 and 1980 than it had been in the previous decade. However, because of the spatial restructuring of both elderly and nonelderly migration, the contribution of elderly migration relative to nonelderly migration increased from 1960 to 1980. Recognizable regional variations were apparent. Elderly migration not only remained significant in explaining changes in elderly population concentrations in "traditional" Sunbelt retirement states but also showed increased importance in newly emergent southern retirement states and in several northern states, including a group in New England.
 
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.
 
Due to increasing evidence for the role of nutrition as a cause of illness and of the efforts of health agencies to induce Americans to change their diets, it is important to monitor populations for changes in their nutrient intakes. Seven-day diet records were collected from 105 free-living men in the 1960s, 1970s, and 1980s. Age range was initially 27 to 65 and finally 50 to 88 years. The men were divided into age groups so that longitudinal, time series, and cross-sectional analyses could distinguish among differences due to aging, cohort, and secular change. Longitudinal decreases over three decades of time include height, intakes of kcal/day, kcal/kg, kcal from fat, and cholesterol (all p less than .0001). Longitudinal increases over time include body weight, intakes of kcal from alcohol (p = .002), kcal from carbohydrate, and polyunsaturated to saturated fatty acid ratio (P/S) (all p less than .0001). Values that correlated cross-sectionally with age in the 1960s were height, kcal/day, kcal/kg, kcal from protein, and P/S ratio; height, intakes of kcal from protein, and fiber in the 1970s; and body weight, height, intakes of kcal from carbohydrate and fiber in the 1980s (all p less than .05). Protein consumption remained constant while carbohydrate increased as time passed. The more striking secular changes were in type and amount of fat consumed (42% to 34% of kcal, a 37% decline in cholesterol and a 72% increase in P/S ratio). Voluntary changes in the diets of these community-dwelling men indicate that, at any age, men can make beneficial changes in intake of nutrients that affect health.
 
Psychological research on human subjects published in the Journal of Gerontology from 1963 through 1974 was summarized along a variety of dimensions, including subject selection procedures, sample characteristics, data analysis techniques, research design, author characteristics, and area of psychological research. Comparison of 1963-1968 with 1969-1974 showed a dramatic increase in the number of studies analyzing data for sex differences and a lessened concern for the health status of subjects. Studies of intellectual/cognitive functioning clearly dominated, while those measuring a physiological variable increased the most over the 12-year span. Discussion focused on variations among studies on definitions of age, concerns with sample description with respect to health, and sex differences.
 
Age-adjusted mortality rates, for all causes of death, are tabulated for all ages by sex for the 55 Ontario counties and districts. The rates are based on all deaths of Ontario residents during 1964-1968 and 1966 census populations. The consistent trends in rates, both for the two sexes and for various 10- and 20-year age groups, indicate that there is a region of about eight adjoining counties, across the center of the province, which has abnormally high mortality, and two regions to the east and west of York, each consisting of three adjoining counties which have abnormally low mortality. The relevance of these findings to aging studies is indicated, and possible further investigations of them are discussed.
 
Two related issues concerning aged return migration are explored in this paper. They are: (1) the common features of states that strongly attract their migration-prone native sons and daughters, and (2) what might account for the differences, if any, in the demographic and socioeconomic characteristics of return and non-return migrants. Individual characteristics of persons, age 60 and over, from the 1970 l-in-100 Public Use Sample of Basic Records were analyzed. A cluster of sunbelt states, and utah, strongly attract return migrants; otherwise they tend to be attracted by states which are popular destinations for aged migration in general. Using discriminant function analysis and tests for mean differences of migrant characteristics, it was found that return migrants tend to be negatively selected on socioeconomic characteristics relative to other interstate migrants. Comparisons of migrant characteristics in streams from New York and ohio to Florida with counterstreams from Florida to New York and ohio were consistent with a model of secondary post-retirement moves to state of birth when service and social support needs increase.
 
Top-cited authors
Dan G Blazer
  • Duke University Medical Center
Eleanor M Simonsick
  • National Institute on Aging
Robert B. Wallace
  • University of Iowa
Pamela W Duncan
  • Wake Forest School of Medicine
Debra K Weiner
  • University of Pittsburgh