As life expectancy increases, there is an ever greater need to keep these additional years disease and disability-free. Research has shown that lifestyle and other environmental influences can profoundly impact outcomes of aging, and that remaining healthy and emotionally vital until advanced ages is a realistic expectation. NIA research is helping to define optimal regimens regarding diet, diet supplements, exercise, safety, and other factors to ensure that endurance, strength, and balance are kept at the highest possible level and that the risks of disease and disability are kept to a minimum.
Story of Discovery—Exercise: A Fountain of Benefits
As the 16th century explorer Juan Ponce de Leon discovered, the fountain of youth does not exist. But scientists of the 20th century have discovered that people can feel younger, stay healthier, and experience a better quality of life through exercise, especially in later years. Exercise benefits both the body and mind, with evidence of increased life expectancy, improved mental health, decreased disability, and, most recently, enhanced learning and memory. Despite the proven benefits of exercise, many Americans—especially older Americans—are not engaging in regular, sufficient physical activity. Older persons often are encouraged to slow down or take it easy, and are given little encouragement for engaging in vigorous activity. The challenge for research is to expand our understanding of the benefits of physical fitness, as well as to identify the factors that motivate and deter people from making exercise a part of their daily routine.
Studies have examined the natural history of physical activity and the impact of lifestyle on health outcomes. An early study showed that, controlling for socioeconomic status and health factors, older people who reported no leisure-time physical activity were found to be at 37% increased risk for mortality as compared to those who reported some physical activity. The potency of lack of exercise as a risk factor was confirmed even for those 75 and older. Subsequent findings made it clear that older people are not exercising as much as they should to achieve the health benefits possible through regular physical activity. Data from the 1988–1991 National Health and Nutrition Examination Study illustrated how inactivity rates increase as people age and differ between men and women, and among racial and ethnic groups. Women were found to be considerably less active than men, and prevalence of leisure-time inactivity was higher among African-Americans and Mexican-Americans than among Caucasians.
The good news is that even moderate physical activity can reap important health benefits, and that it is never too late to start adopting healthier lifestyles. In a recent study, physically active older individuals had double the likelihood of living the remainder of their lives with no disability compared to sedentary adults. They are also more likely to live to advanced old age and to remain independent in basic self-care activities in the year prior to their deaths. In this study, moderate physical activity included walking and gardening, activities feasible for many older adults. Groundbreaking studies reported in 1994 involving frail nursing home residents from 72 to 98 years old found that a 10-week resistance exercise program approximately doubled leg strength, increased walking speed, improved stair-climbing power, and led to increased spontaneous physical activity, when compared to controls.
Since the early 1990s, several exercise-oriented intervention studies have been conducted to reduce frailty and injuries. Falls are the primary cause of the more than 250,000 hip fractures that occur each year among older persons. One intervention strategy that included exercise produced a 44% lower rate of falls than a control group. Exercise can also benefit people suffering from a variety of physical ailments, such as osteoarthritis, a common condition that causes pain and activity limitation in older people. For example, the Fitness Arthritis and Seniors Trial tested the long-term utility of aerobic training (walking) or resistance training (weight lifting) in helping older people with knee osteoarthritis maintain their function and quality of life. Participants reported less pain and better function than controls. Studies on the effects of exercise on chronic pain and peripheral arterial disease observed similar positive results, particularly regarding improved pain management.
Studies have begun to identify a link between exercise and increased life expectancy. In one study, higher fitness was associated with lower mortality rates in men aged 20 to 82. The study found that unfit men age 60 and over who later became fit had death rates 50% lower than those who remained unfit. In another study, people who reported moderate to high levels of exercise lived three or more years longer than less active study participants.
Research on the effects of exercise on the body’s neurological function have produced exciting new findings. Animal studies have shown that exercise can enhance generation of brain cells, which may someday mean that replacement of neurons lost through age, trauma, or disease might be enhanced via a regimen that includes the use of exercise. In humans, exercise can attenuate age-related decline in some cognitive skills. The beneficial effect of aerobic exercise is selective—it seems to affect only those functions associated with frontal regions of the brain. A recent study examined the effect of increased light aerobic activity on tests of planning, scheduling, and short-term memory, and the inhibition of inappropriate responses. Remarkably, previously sedentary adults, age 60 to 75, with small increases in aerobic fitness due to six months of light to moderate walking, showed substantial improvement in these higher thinking tasks. There were no increases in tasks associated with other regions of the brain, such as short-term memory.
Exercise not only helps daytime functioning, it also helps individuals get a good night’s sleep. Two independent randomized controlled trials among older adults with moderate sleep complaints showed that exercise improved quality of sleep. The first study used an intervention of low-impact aerobics and brisk walking for 30 to 40 minutes four times a week over a 16-week period. Compared to a control group, who did not change their physical activity levels, the exercise group had significant improvements in sleep latency (a 50% reduction, about 15 minutes), sleep duration (increase of almost an hour), and quality of sleep.
The second study used an intervention of progressive resistance training of the large muscle groups for about one hour three days a week for 10 weeks. The control group participated in a health-education program. The participants were depressed elders, aged 60 to 84 years. The exercise regimen resulted in subjective improvement of sleep quality as well as a 50% reduction in depression measures. Work continues on which types of exercise activities and intervention strategies are most effective for initiating and maintaining physical activity within a diverse, aging population.
Science Advances—Reducing Chronic Disease and Disability
Delirium Can Be Prevented in Hospitalized Older Patients. Delirium, an acute confusional state, in older hospitalized older patients is associated with poor outcomes, and is a common, serious, and potentially preventable source of both prolonged illness and early death. Between 20–30 percent of all hospitalized elderly patients have episodes of delirium, resulting in treatment costs exceeding $4 billion per year in the U.S.5 Previous studies of delirium focused on the treatment of delirium rather than on primary prevention. A recent study evaluated the effectiveness of a multicomponent strategy for the prevention of delirium. Study participants received either usual, standard hospital care or care under a multidisciplinary team of specialists that included staff nurses, recreational therapists, physical therapists, geriatricians, and trained volunteers. Patients in this study had one or more of six risk factors for delirium, including cognitive impairment, sleep deprivation, immobility, dehydration, or impaired vision or hearing. To address these risk factors, team members were trained to recognize and counteract the danger signs before confusion, agitation, and hallucinations set in. Interventions include making sure patients got enough fluids, taking them for walks, and providing warm drinks at bedtime to promote sleep. While 15% of patients receiving standard hospital services experienced at least one episode of delirium, only 9.9% of those receiving the team approach experienced an episode. Once an initial episode of delirium had occurred, however, the intervention had no significant effect on the severity of delirium or the likelihood of recurrence. This study holds substantial promise for the prevention of delirium in hospitalized older patients. Further evaluation is needed to determine the cost effectiveness of intervention to prevent delirium and its effects on related outcomes, such as mortality, rehospitalization, institutionalization, use of home health care, and long-term cognitive functioning.
Predictors of Healthy Aging Can Be Identified and Interventions Can Reduce Risk of Disability. There is a need to understand whether there are modifiable risk factors that can decrease the risk of disability and death with aging. A long-term study with Japanese-American men in Hawaii has shown that these men have one of the highest life expectancies of all Americans. Because a number of baseline measurements were taken of these men in midlife, from 45 to 68, it was possible to explore predictors of long life expectancy and prevention of physical disability. Among over 6500 healthy men at baseline, about 60% remained free of major illness and were not physically or cognitively impaired over the next 25 years. Data from midlife that proved to be predictive of healthy aging included optimal blood pressure, low blood sugar and cholesterol levels, lack of obesity, lack of smoking, and strong hand grip. At an older age the men were examined to determine the presence of functional limitation and disability. Of various factors considered, midlife hand grip strength was associated with less physical disability and faster walking speed. In a clinical trial, participants were randomized into intervention and control groups. At the end of one year after a regimen of increased physical activity and chronic-illness self-management, the intervention group experienced fewer hospitalizations and fewer total hospital days. Factors leading to a long and active life are of prime importance as the population ages worldwide. This study suggests that preventive and/or therapeutic interventions are most effective when initiated at younger ages, although the clinical trial results suggest that successful intervention can occur at older ages. Researchers will need to work with clinicians to develop strategies to address modifiable risk factors in order to better promote healthy aging.
Testosterone Replacement for Older Men May Have Protective Effects Against Age-Related Diseases. Many older men have blood levels of testosterone well below the normal range for younger men. Earlier studies have shown that low testosterone levels may increase risk factors for disease and disability, including loss of bone (leading to osteoporosis and fractures), loss of muscle (causing decreased strength), and increases in body fat (increasing risks for diabetes and heart disease). In a recently completed clinical trial of men over 65 years old with low serum testosterone, study participants were given a testosterone or placebo skin patch for three years. Levels of testosterone in the treatment group rose to those generally found in younger men. Men with the lowest endogenous serum testosterone (3 micrograms per liter or less) prior to beginning the trial had significant increases in bone density in response to testosterone replacement. The testosterone treatment also increased lean body tissue and significantly decreased body fat. Study participants were monitored for possible adverse treatment effects, particularly on the prostate. Testosterone treatment did not increase symptoms of an enlarged prostate, such as impaired urinary function, nor was there statistically significant evidence that the administered testosterone increased the incidence of prostate cancer.The results of this study suggest that testosterone replacement could help protect many older men with low testosterone levels against common diseases of aging such as diabetes, heart disease, and osteoporosis. However the possibility that testosterone replacement could increase adverse events such as prostate diseases, though not observed in this small study, reinforces the need for well-designed larger studies as well as the development of strategies to minimize risks of testosterone therapy while still providing benefits.
Postmenopausal Estrogen Has a Positive Influence on Women’s Arteries. Arterial stiffness has been identified as a potential risk factor for cardiovascular disease. Earlier research has shown that estrogen may improve blood vessel pliability by altering the structure and function of vascular tissue, including smooth muscle cells. This study examined the influence of age and current estrogen replacement therapy (ERT) on stiffness in the common carotid arteries (the main arteries that pass up the neck and supply blood to the head). The common carotid arteries of 172 women, 37 of whom were current users of ERT, were examined by ultrasound, and the degree of arterial stiffness was measured. Arterial stiffness was found to increase linearly with age, and was modestly related to other cardiac risk factors. The degree of stiffness was lower in women using ERT than in postmenopausal nonusers. Furthermore, the effects of age and ERT on the stiffness persisted after adjustments for other cardiovascular risk factors. Carotid stiffness was similar in ERT users, whether or not they also took progesterone. This study suggests that the cardiovascular protection seen in women using ERT may involve overall reduction of age-associated arterial stiffening.
Chronic Inflammation in the Elderly Predicts Disability and Early Death. Inflammation is a normal biologic response of the immune system to a number of different stimuli, including infections, allergens, and physical trauma. However, inflammation can become chronic and increase the onset and severity of a number of age-related disabilities and diseases. An indicator of this process is the elevation of a proinflammatory protein, interleukin-6 (IL-6), which plays a central role in inflammation and increases with age. High circulating levels of IL-6 may contribute to functional decline in old age and an increase is observed in such diverse conditions as depression, heart failure, and arthritis. One study of nearly 1,700 men and women, aged 70 or greater living in North Carolina, measured IL-6 levels against a standardized test for depression. After controlling for age, race, and gender, IL-6 levels remained the only biologic variable significantly associated with depression. In another study in men and women 71 years or older, participants with the highest levels of interleukin-6 were almost twice as likely to develop mobility-disability and were about twice as likely to die within 5 years of the beginning of the study. It is known that IL-6 stimulates the synthesis of C-reactive protein, an indicator of systemic inflammation. When levels of both IL-6 and C-reactive protein were elevated simultaneously, there was a 3-fold increased risk of mortality. Further studies are needed to improve our understanding of the complicated system of stimulus and response with regard to inflammation. These findings may broaden our understanding of the health correlates and consequences of chronic inflammation, as well as provide a new way to identify high-risk individuals to determine whether they would benefit from anti-inflammatory intervention.
Behavioral Training Is More Effective Than Drug Therapy for Urge Urinary Incontinence. Approximately 15 million Americans adults have urinary incontinence (UI) with associated health costs estimated in a range of $16–$26 billion dollars annually.6,7 Urinary incontinence is especially a problem for women. Nearly 40 percent of community dwelling women age 60 years and older suffer from some form of UI. While behavioral training and drug therapy have both been previously demonstrated to be effective treatments for urge urinary incontinence in older adults, drug therapy is commonly used as the first course of treatment. A recent clinical trial directly compared behavioral training (instrument-assisted pelvic muscle exercises to improve bladder control) to drug treatment for urge UI in older women and demonstrated that behavioral training was significantly more effective than drug therapy in reducing the episodes of accidental urine loss. Thus, behavioral training should be considered the first treatment option given the potential side effects of drug therapy, and to avoid further problems with drug interactions among older persons taking multiple medications.
- Inouye SK, Bogardus ST, Charpentier PA, Leo-Sumers L, Acampora D, Holford TR, Cooney LM. A Multicomponent Intervention to Prevent Delirium in Hospitalized Older Patients. NEJM 340:9; 669-676. March 1999.
- Fantl JA, Newman DK, Coiling J, et.al. Urinary Incontinence in Adults: Acute and Chronic Management, Rockville, MD: US Dept of Health and Human Services, Public Health Service, Agency for Health Care Policy and Research; 1996. Clinical Practice Guideline No. 2, 1996 Update, AHCPR publication No. 96-0682.
- Wagner TH, Hu TW. Economic Costs of Urinary Incontinence in 1995. Urology. 51:3;355-361. 1998.