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Biomedical subjects

S J Birge

Publications and source records attributed to S J Birge.

At least 19 recordsLinked to original sources
PubMed1998

HRT preserves increases in bone mineral density and reductions in body fat after a supervised exercise program.

The aims of this study were to confirm our previous finding that hormone-replacement therapy (HRT) augments exercise-induced increases in bone mineral density (BMD) in older women and to determine whether HRT preserves the adaptations when exercise is reduced or discontinued. The study included an 11-mo treatment phase and a 6-mo follow-up phase. Participants, aged 66 +/- 3 yr, were assigned to control (Con; n = 10), exercise (Ex; n = 18), HRT (n = 10), and Ex+HRT (n = 16) groups. HRT was continued during the follow-up. After the treatment phase, changes in total body BMD were -0.5 +/- 1.7, 1.5 +/- 1.4, 1.2 +/- 0.8, and 2.7 +/- 1.2% in Con, Ex, HRT, and Ex+HRT, respectively. Ex+HRT was more effective than HRT in increasing BMD of the total body and tended (P = 0.08) to be more effective at the lumbar spine. Ex+HRT was more effective than Ex in increasing BMD of the total body, lumbar spine, and trochanter. Exercise-induced gains in BMD were preserved during the follow-up only in those individuals on HRT. HRT also attenuated fat accumulation, particularly in the abdominal region, after the exercise program. These findings suggest that HRT is an important adjunct to exercise for the prevention not only of osteoporosis but also of diseases related to abdominal obesity.

Aged↗
PubMed1998

Hormones and the aging brain.

There is a growing appreciation of the role of ovarian hormones as modulators of neuronal function within the central nervous system. Ovarian failure has long been known to result in reversible changes in mental function, affect, and behavior. Only recently have we begun to appreciate the potential role of these hormones, specifically estrogen, in the aging of the brain and in the expression of Alzheimer's disease. As a consequence of the estrogen deficiency state of the postmenopausal woman, brain aging may be accelerated, resulting in the greater incidence of injurious falls and accidental injuries in women than in men of the same age. This sex steroid deficiency in postmenopausal women may also account for the earlier expression of Alzheimer's disease in women.

Aging↗
PubMed1997

Hormone replacement therapy does not augment gains in muscle strength or fat-free mass in response to weight-bearing exercise.

Lower extremity strength and fat-free mass were examined in 58 postmenopausal women aged 60-72 yr. Subjects were studied before and after an 11-mo control period (n = 16) or before and after an 11-mo weight-bearing exercise training program designed to generate relatively high ground reaction forces (n = 42). Twenty-two of the exercisers initiated hormone replacement therapy (HRT) at the outset of exercise and continued HRT for 11 mo. Hip extension and abduction strength were assessed using a hand-held dynamometer. Force production during knee extension and flexion was evaluated on an isokinetic dynamometer at 60, 90, and 180 degrees/s. Simultaneous knee and hip extension strength was also assessed on a leg press machine. Total body and lower extremity fat-free mass were determined using dual-energy x-ray absorptiometry. There were no significant changes in muscle strength or body composition in control subjects. Both exercise groups had significant increases in fat-free mass and in all strength measures. Fat-free mass increased from 38.8 +/- 4.3 to 39.7 +/- 4.3 kg in the exercise group and from 37.7 +/- 3.9 to 38.9 +/- 4.6 kg in the exercise-plus-HRT group. The average relative increase in strength was 16.2 +/- 11.0% in the exercise group and 17.0 +/- 13.0% in the exercise-plus-HRT group. Women receiving HRT did not have a gain in fat-free mass or in strength over and above that demonstrated by the women not on HRT. Our results provide evidence that HRT does not augment the increases in muscle mass or strength that occur in response to weight-bearing exercise in older women.

Absorptiometry, Photon↗
PubMed1997

The role of estrogen in the treatment of Alzheimer's disease.

Multiple factors appear to contribute to the expression of Alzheimer's disease (AD). About 30 percent of cases of dementia of the Alzheimer's type can be attributed to genetic factors. These observations raise the possibility of identifying multiple interventions that may modify the disease process and, therefore, the clinical expression of the dementia. Prominent among factors that may contribute to dementia and, specifically, to dementia of the Alzheimer's type is cerebral vascular disease. Estrogen is a potent factor that not only prevents vascular disease but also improves blood flow in diseased vessels, including blood flow in regions on the brain affected by AD. Estrogen also has direct effects on neuronal function that may play an important role not only in the preservation of neurons but in repair of neurons damaged by disease process. These effects of estrogen on the CNS suggest that the hormone may be effective not only in the prevention of dementia but also in its treatment. The results of clinical trials, reviewed in this presentation, are very promising but are limited by the paucity of subjects and often the lack of adequate controls. Larger, randomized, placebo-controlled trials are needed to definitively establish the efficacy of estrogen in the treatment of dementia of the Alzheimer's type.

Alzheimer Disease↗
PubMed1997

Effects of exercise involving predominantly either joint-reaction or ground-reaction forces on bone mineral density in older women.

This study compared the effects of two exercise training programs, 11 months in duration, on bone mineral density (BMD) in older, sedentary women. Thirty-nine women, aged 60-74 years, were assigned to the following groups: (a) a group that performed exercises that introduced stress to the skeleton through ground-reaction forces (GRF) (i.e., walking, jogging, stairs); (b) a group that performed exercises that introduced stress to the skeleton through joint-reaction forces (JRF) (i.e., weight lifting, rowing); or (c) a no-exercise control group. BMD of the whole body, lumbar spine, proximal femur, and distal forearm was assessed five times at approximately 3-month intervals. The GRF and JRF exercise programs resulted in significant and similar increases in BMD of the whole body (2.0 +/- 0.8% and 1.6 +/- 0.4%, respectively), lumbar spine (1.8 +/- 0.7% and 1.5 +/- 0.5%, respectively), and Ward's triangle region of the proximal femur (6.1 +/- 1.5% and 5.1 +/- 2.1%, respectively). There was a significant in BMD of the femoral neck only in response to the GRF exercise program (GRF, 3.5 +/- 0.8%; JRF, -0.2 +/- 0.7%). There were no significant changes in BMD in control subjects. Among all exercisers, there was a significant inverse (r = -0.52, p < 0.01) relationship between increases in whole body BMD and reductions in fat mass, suggesting a dose response effect of exercise on bone mass. Although femoral neck BMD was responsive only to the GRF exercise program, some adaptations (i.e., increase in lean body mass and strength) that were specific to the JRF exercise program may be important in preventing osteoporotic fractures by reducing the risk for falls. It remains to be determined whether all of these benefits can be gained through a training program that combines the different types of exercises employed in this study.

Aged↗
PubMed1996

Effects of endurance exercise and hormone replacement therapy on serum lipids in older women.

OBJECTIVE: To determine the effects of 11 months of exercise training and hormone replacement therapy (HRT), alone or in combination, on serum lipids and lipoproteins, in postmenopausal women. DESIGN: Controlled, prospective, 11-month clinical trial. Healthy postmenopausal women (n = 71, age range 60-72 yrs) were assigned to four groups in a 2 X 2 design (control, exercise, HRT, exercise + HRT). SETTING: Large, midwestern urban community; subjects were recruited from the community-at-large. The exercise program was conducted at a university exercise facility. INTERVENTIONS: HRT consisted of conjugated estrogens at 0.625 mg/day and trimonthly medroxyprogesterone acetate 5 mg/day for 13 days. Exercise consisted of 2 months of low intensity exercise followed by 9 months of vigorous exercise for 45 min/day, 3 or more days/week, at 65-85% of maximal heart rate. MEASUREMENTS: Maximal aerobic power (VO2max), resting blood pressure, body composition, serum lipids and lipoproteins, and dietary intake at baseline and after 11 months. MAIN RESULTS: At the end of 11 months, subjects in the exercise group had decrease total cholesterol (TC; P < .01) and LDL-cholesterol (LDL-C; P < .05), but there was no change in HDL-cholesterol (HDL-C) or triglycerides. Women in the HRT group had decreased LDL-C (P < .001) and increased HDL-C (P < .01) and triglycerides (P < .01), but there was no change in TC. Exercise + HRT subjects had decreased TC (P < .05) and LDL-C (P < .001), and increased HDL-C (P < .001); exercise prevented the HRT-related increase in triglycerides. CONCLUSIONS: Endurance exercise training and HRT have independent and complimentary effects on serum lipids profiles in healthy postmenopausal women. Such effects are likely to reduce the risk of cardiovascular morbidity in this population.

Aged↗
PubMed1996

Is there a role for estrogen replacement therapy in the prevention and treatment of dementia?

Studies in experimental animal models provide a convincing rationale for a role for ERT in the treatment and prevention of dementia. These studies establish the role of estrogen in the regeneration and preservation of neuronal elements within the CNS that are analogous to those regions of the brain most sensitive to the neurodegenerative changes associated with AD. Furthermore, behavioral studies in these animals establish a correlation between the hormone dependent changes in the neuronal architecture and learning and memory. However, extrapolation of these studies to post-menopausal women must be done with caution. Surgical and natural loss of ovarian function does not result in a clinically relevant decline in cognitive function over the short term (1 to 2 decades) or ever in some women. The modest changes that are observed may relate to the hormone's effect on neurotransmitter levels or their receptors. Although Singh et al. noted changes in neurotransmitter concentrations 5 weeks after ovariectomy, changes in cognitive performance in their rat model did not become significant until 28 weeks after ovariectomy--the equivalent of approximately 2 decades of human life. Except for the familial forms of the disease, AD is rarely seen in the first 2 decades after the menopause. However, by the third decade after the menopause, 50% of women can be expected to manifest the histopathological changes of AD. Approximately half of these women are without clinical evidence of disease. Thus, the neurodegenerative process of AD probably precedes by many years the age of onset of the disease. We do not know what factors contribute to the selective neuronal injury which, over time, eventually leads to the neuronal loss and reduced synaptic density that result in the cognitive impairment of AD. At this time we can only speculate as to estrogen's role in modifying this process. Data from experimental animal models suggest that estrogen deficiency would selectively increase the vulnerability of estrogen-responsive neural elements, for example, the cholinergic neurons of the basal forebrain and hippocampus--offulnerability mediated perhaps by the reduced expression of neurotrophic factors, decreased clearance of the amyloid protein, and/or reduced cerebral blood flow that are associated with estrogen deficiency. The brain's ability to adapt to the neuronal loss by stimulating axonal and synaptic regeneration would also be impaired by estrogen deficiency as suggested by estrogen's ability to restore the synaptic density of lesioned brains of ovariectomized animals. Thus, estrogen deficiency, like the apolipoprotein E4 allele, can be considered not a cause of AD but one of perhaps several factors modifying the neuronal injury and loss leading to AD. The limited epidemiologic data and intervention trials currently available are consistent with this interpretation. Because of the urgency and enormity of the problem of dementia in our aging society, there would now appear to be sufficient reason to allocate the resources needed to conduct the appropriate clinical trials to determine estrogen's efficacy in both the treatment and prevention of this devastating condition. These trials are needed so that women and their physicians can adequately weigh the risks and benefits of hormone replacement for the treatment and, more importantly, the prevention of dementia.

Alzheimer Disease↗
PubMed1996

Serum leptin levels are reduced in response to exercise training, but not hormone replacement therapy, in older women.

The aim of this study was to evaluate the effects of exercise training and hormone replacement therapy (HRT) on serum leptin levels in older women. Previously sedentary, healthy women, aged 60-72 yr, were assigned to control (n = 16), exercise (n = 17), HRT (n = 15), or exercise + HRT (n = 13) groups. Exercise training consisted of a 2-month flexibility-exercise program followed by a 9-month exercise program that included walking, jogging, and stair climbing. HRT consisted of 11 months of continuous conjugated estrogens (0.625 mg/day) and medroxyprogesterone acetate (5 mg/day) for 13 days every third month. Body composition was assessed by dual-energy x-ray absorptiometry, and serum insulin levels were measured in the fasted state and in response to a glucose challenge. Leptin levels were reduced by 23 +/- 25% and 22 +/- 27% (both P < 0.01) in response to exercise and exercise + HRT, respectively. There was no effect of HRT on leptin. Fat mass was the strongest predictor of serum leptin concentration, both before (r = 0.81; P < 0.001) and after (r = 0.85; P < 0.001) the study period, and the change in fat mass in the exercisers was significantly correlated with the change in leptin (r = 0.55; P < 0.01). There did not seem to be an effect of exercise, independent of the reduction in fat mass, on leptin. Insulin levels were significantly correlated with leptin levels, but this was not independent of the association with adiposity. The curvilinear relationship between leptin level and fat mass and the finding that the ratio of leptin mass to fat mass decreased after weight loss suggest that fat cell size is an important determinant of circulating leptin levels.

Adipose Tissue↗
PubMed1995

Additive effects of weight-bearing exercise and estrogen on bone mineral density in older women.

The separate and combined effects of weight-bearing exercise and hormone replacement therapy (HRT) on bone mineral density (BMD) were studied in 32 women, 60 to 72 years of age. HRT consisted of continuous conjugated estrogens 0.625 mg/day and trimonthly medroxyprogesterone acetate 5 mg/day for 13 days. Exercise consisted of 2 months of low-intensity exercise followed by 9 months of more vigorous weight-bearing exercise approximately 45 minutes/day, > or = 3 days/week, at 65-85% of maximal heart rate. Lumbar spine and proximal femur BMD were significantly increased in response to exercise and to HRT, and total body BMD was significantly increased in response to HRT; neither exercise nor HRT had an effect on wrist BMD. The combination of exercise + HRT resulted in increased BMD at all sites except the wrist, with effects being additive for the lumbar spine and Ward's triangle and synergistic for the total body. Based on reductions in serum osteocalcin levels, it appears that increases in BMD in response to HRT and exercise + HRT were due to decreased bone turnover. The lack of change in serum osteocalcin and IGF-I in response to exercise alone suggests that increases in BMD were due to decreased bone resorption and not increased formation. Results indicate that weight-bearing exercise + HRT may be effective in preventing and/or treating osteoporosis. It is likely that the additive effects of weight-bearing exercise and HRT on bone mineral accretion, coupled with other adaptations to the exercise (i.e., increased strength and functional capacity), could effectively reduce the incidence of falls and osteoporotic fractures.

Aged↗
PubMed1995

Differential effects of estrogen treatment on bone mineral density of the spine, hip, wrist and total body in late postmenopausal women.

It is commonly believed that estrogen is effective only in preventing menopause-related loss of bone mineral. However, recent studies found significant increases in bone mineral density (BMD) of the spine in response to estrogen, particularly in older women. The degree to which estrogen can restore BMD of the hip is uncertain. In the present study, changes in BMD of the lumber spine (L2-4), hip (neck, trochanter and Ward's triangle), wrist (ultradistal) and total body in response to 1 year of hormone replacement therapy (HRT) were evaluated by dual-energy X-ray absorptiometry (DXA) in women 10 or more years past menopause. Twelve women, aged 61-74 years, received conjugated estrogens 0.625 mg and cyclic medroxyprogesterone acetate 5 mg; 12 women who did not receive HRT were controls. Calcium intake was adjusted to approximately 1500 mg/day in all subjects. There were no differences between the groups in BMD prior to treatment. Increases in BMD of the lumbar spine (mean +/- SD, 0.041 +/- 0.030 g/cm2), hip (neck, 0.019 +/- 0.018 g/cm2; trochanter, 0.017 +/- 0.012 g/cm2; Ward's triangle, 0.026 +/- 0.029 g/cm2) and total body (0.013 +/- 0.016 g/cm2) occurred in response to HRT, and these changes were significantly different from those in controls (spine, 0.005 +/- 0.020 g/cm2; neck, -0.007 +/- 0.026 g/cm2; trochanter, 0.002 +/- 0.014 g/cm2; Ward's triangle, 0.003 +/- 0.019 g/cm2; total body, -0.001 +/- 0.017 g/cm2). HRT appears to be most effective at weight-bearing sites that have a high cancellous bone content.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Estrogen replacement therapy and postural stability in the elderly.

Postural instability and falls in the elderly patient constitute a major health care problem. The etiology is often multifactorial, involving abnormal sensory input (visual, vestibular, and somatosensory), poor central processing, and suboptimal musculoskeletal biomechanics. Estrogen replacement therapy has been shown to prevent Alzheimer's disease and to improve cognitive performance in women with dementia. It was, therefore, postulated that estrogen replacement may improve central processing speed, which would result in improved postural stability. In this prospective, randomized, double-blinded study, 87 elderly female subjects (age > 69) were examined by repeated dynamic platform posturography, to measure the effect of estrogen therapy versus placebo upon postural stability. Results indicate that those receiving estrogen had no significant improvement in postural stability at 2 and 8 months of treatment relative to those receiving placebo. Trail Making B test was used as the psychometric test of central processing speed. There was no significant effect of estrogen on this measure over the 8 months of observations. It is concluded that 8 months of estrogen replacement therapy has no significant effect on central processing speed or postural stability in a healthy older female population.

Aged↗
PubMed1994

The prevalence and correlates of fear of falling in elderly persons living in the community.

OBJECTIVES: Fear of falling has been recognized as a potentially debilitating consequence of falling in elderly persons. However, the prevalence and the correlates of this fear are unknown. METHODS: Prevalence of fear of falling was calculated from the 1-year follow-up of an age- and gender-stratified random sample of community-dwelling elderly persons. Cross-sectional associations of fear of falling with quality of life, frailty, and falling were assessed. RESULTS: The prevalence of fear increased with age and was greater in women. After adjustment for age and gender, being moderately fearful of falling was associated with decreased satisfaction with life, increased frailty and depressed mood, and recent experience with falls. Being very fearful of falling was associated with all of the above plus decreased mobility and social activities. CONCLUSIONS: Fear of falling is common in elderly persons and is associated with decreased quality of life, increased frailty, and recent experience with falls.

Accidental Falls↗
PubMed1994

Hip fracture.

One of the major factors contributing to a deterioration in the quality of life and independence of older adults is osteoporosis and hip fracture. Recent advances in our knowledge of the causes of hip fracture are providing new and effective approaches to the prevention of this disabling condition. Because hip fracture is a leading cause of disability, significant efforts have been directed to the development of strategies for the more effective rehabilitation and treatment of the fracture patient.

Accidental Falls↗
PubMed1993

Clock completion: an objective screening test for dementia.

OBJECTIVE: To develop a simple, readily administered and scored screening test for dementia utilizing the clock-drawing task. DESIGN: Retrospective analysis of clock-drawing errors and prospective validations. SETTING: Hospital-based outpatient geriatric assessment clinic, rehabilitation service, apartment building for older adults, and long-term care facility. PARTICIPANTS: Convenience sample of patients attending the geriatric assessment clinic, patients on the rehabilitation service, or residents of the above sites. MEASUREMENTS: Sensitivity and specificity of a clock-scoring system in identifying patients with dementia and the comparison of this system with the Short Blessed Test (SBT) in the diagnosis of dementia and in the prospective validation of the test. RESULTS: Of the 10 clock-drawing errors evaluated, placement of digits in a pre-drawn circle had the greatest sensitivity and specificity in distinguishing patients with irreversible dementia from patients with other disorders who did not meet NINCDS-ADRDA criteria for probable dementia. The derived scoring system had a sensitivity of 87% and a specificity of 82%, compared with a sensitivity of 82% and a specificity of 88% for the SBT in identifying dementia. Test-retest reliability for the distinction between demented and non-demented was 82%, with a Kappa of 0.63 for the clock completion, and 82%, with a Kappa of 0.62 for the SBT. Inter-rater reliability for clock completion was 0.90 to 0.93. CONCLUSION: A simple, completely objective scoring system for a clock completion test has been developed which involves only the number of digits placed in the fourth quadrant of a pre-drawn circle. This readily administered test is as effective in screening for dementia as the longer six-item SBT.

Aged↗
PubMed1993

Age-related differences in body composition by hydrodensitometry and dual-energy X-ray absorptiometry.

To determine whether percent body fat (%BF) is overestimated in older people by hydrodensitometry (HD) because of an age-related decrease in bone mineral content (BMC), body composition of 113 women and 72 men (21-81 yr) was assessed by HD and dual-energy X-ray absorptiometry (DEXA). DEXA provides an estimate of %BF adjusted for differences in BMC. HD %BF and DEXA %BF were not different in young people [21-39 yr; 17.6 +/- 6.4 (SD) vs. 17.6 +/- 7.2%, NS], were slightly, but significantly, different in middle-aged people (40-59 yr; 25.5 +/- 6.4 vs. 24.1 +/- 6.7%, P < 0.05), and showed the largest disparity in older people (> or = 60 yr; 34.9 +/- 7.9 vs. 30.8 +/- 8.7%, P < 0.05). The discrepancy in older people was apparently not due to mineral loss, however, inasmuch as correction of HD %BF for variance in BMC as a fraction of fat-free mass resulted in only small adjustments (approximately 1%) of %BF. Assessment of DEXA %BF was further evaluated in nine subjects with packets of lard (2-3 kg) overlying either the thigh or the trunk region. Only 55% of the exogenous fat was identified as fat when it was in the trunk region compared with 96% when it was positioned over the legs. These data suggest that the age-related increase in upper body adipose tissue is underestimated by DEXA.

Absorptiometry, Photon↗
PubMed1993

Osteoporosis and hip fracture.

Recent studies have identified multiple factors contributing to osteoporosis and hip fracture in women. It is now possible to identify individuals who are at increased risk of osteoporotic fractures through bone densitometry, so that appropriate measures for the prevention and restoration of bone loss can be instituted. Although largely experimental, such measures are available. Prevention of hip fracture, however, may best be accomplished by preventing falls or the trauma associated with the fall in those identified at increased risk. Promising interventions are also available to reduce those risks, e.g., exercise programs, cataract surgery, and environmental modification such as hand rails and foam-backed carpeting. A major factor contributing to fall-associated fractures is a decline in mental function. Here too there may be effective measures to alter this decline in mental function and specifically the central integration of sensory input. Clinicians await with great interest the results of the proposed intervention studies of the Women's Health Initiative evaluating vitamin D and hormone replacement therapy.

Age Factors↗