NATIONAL INSTITUTE ON AGING

THE BALTIMORE LONGITUDINAL STUDY OF AGING--1958 - 1983

In 1983, the Baltimore Longitudinal Study of Aging (BLSA) celebrates its twenty-fifth anniversary. Before the BLSA was established in 1958, most research on aging involved sick institutionalized elderly. This innovative program now part of the National Institute on Aging's Gerontology Research Center, set out to measure physiological and psychological functions in healthy community-living volunteers over long periods of time and to address questions such as: How do the changes that occur with normal aging differ from those associated with disease? How does one's age affect the course of various diseases? Why do some individuals keep their physical and mental health better than others? How do major life changes, such as retirement and death of spouse, affect physical and mental health, and life expectancy? What can individuals or society do to promote healthful aging?

To answer these and other questions required volunteers willing to travel to Baltimore to undergo extensive physical examinations, take tests of memory and learning abilities, and answer detailed questions about their social and behavioral patterns. The BLSA's first volunteer, Dr. W. W. Peter, a retired Public Health Service physician, enthusiastically recruited many of his colleagues to participate in the small project then housed in a men's ward at Baltimore City Hospitals. In 1978, the BLSA was expanded to include women. Today over 1000 volunteers, ranging in age from 20 to 96 years, return to the Gerontology Research Center every two years for 2 l/2 days of testing.

Recent Research Developments

The BLSA is a series of overlapping longitudinal studies, unique in their diversity and intensity. The research shows that different body systems vary greatly in rates of change, and that BLSA volunteers have wide individual differences as they age, with many older persons performing as well as younger persons on some tests. In some cases, performance improves over time as a result of lifestyle changes -- such as adding daily exercise.

BLSA studies show that when it is free of disease, the heart of an older person pumps about as well as that of a younger adult. At the same time, coronary artery disease (CAD) appears to be more prevalent than previously documented. These discoveries were made using a new painless technique called stress/thallium testing. BLSA investigators and scientists at The Johns Hopkins Hospital gave study members a small dose of the radioactive element thallim during strenuous tread-mill exercise. This allowed cardiologists to assess the adequacy of blood flow to the heart muscle.

First, conventional electrocardiograms were given to 233 volunteers. These tests found 22 percent of those in their seventies with CAD. Thallium scanning added to exercise electrocardiography revealed 56 percent of the same group with the disorder, many with no previous signs of heart disease. Thirty-six volunteers free of CAD on stress/thallium tests were given another radioactive element, technetium 99, to measure the quantity of blood ejected with each stroke of the heart during exercise. The tests showed no age-associated reduction in pumping of blood, even during vigorous exercise.

Most healthy older BLSA men produce sex hormones at levels comparable to those found in younger men, studies show. This means the decline in sexual vigor with aging reported by some male volunteers is not due to a hormone deficiency as had been assumed previously. In the oldest subjects studied--men aged 70 to 89--sex hormone levels were higher in those who maintained greater levels of sexual activity. The sperm counts in older men were about the same as those in younger men but the proportion of immature sperm increased with age.

It often has been assumed that unstable sexual or marital relationships, or that the quantity or type of sexual activity may contribute to the developent of benign prostatic hypertrophy (BPH), enlargement of the prostate gland. The condition occurs very commonly in men over age 60. However, a comparison between BLSA men who had surgery for BPH and men of the same ages who did not require surgery, revealed no important differences in amount of sexual activity, number of sexual partners, or length or stability of marriage.

Certain cells important to the body's immune mechanisms, the lymphocytes, have a markedly decreased ability to kill human tumor cells beginning as young as age 40, according to longitudinal study data. In addition, neutrophils, cells which fight acute infection, appear to become less efficient with advancing age. These changes in immune function may influence susceptibility to cancer and infectious diseases -- two of the most life-threatening conditions of old age. These findings lay the groundwork for future studies to develop ways to take advantage of those immune functions that continue to perform well with aging and to find ways to enhance the immune system's ability to fight disease.

Dermatoglyphics are hand and foot print patterns unique to each individual even before birth. Longitudinal study scientists, collaborating with the World Health Organization and other institutions, are studying possible dermatoglyphic patterns associated with cancer, diabetes, heart and other diseases. So far, they have found significant dermatoglyphic differences between breast cancer patients, those at high risk of developing breast cancer and volunteers who were in neither of those categories. These studies may lead to the expanded use of dermatoglyphics to detect individuals at high risk for certain diseases associated with aging.

Physical appearance may provide clues to general health, according to a study in which over 1000 BLSA men took tests of lung function, basal metabolic rate, visual and hearing acuity, and motor coordination. In addition, physicians determined independently whether the men looked older or younger than their chronological ages. Those who looked older to the physicians generally had performed more poorly on biological tests.

In other BLSA studies, performance on biological tests was associated with lifestyle, health and possibly genetics. Volunteers in poor physical or mental health, and who were fatter or less active, tended to have lower performance. Better educated persons tended to be better performers.

There are many known adverse effects of even moderate obesity. However, the lowest mortality among BLSA volunteers and in over 40 studies worldwide occurred in women and men whose weights were average or above average. These findings led to the suggestion that standards for normal body weight should reflect somewhat higher weights. The recent modifications of standard height and weight tables were consistent with these findings.

BLSA scientists have documented an age-related reduction in the body's cellular water. This has important implications for future studies to determine safe drug doses for older people. A lower amount of water in the body means that identical doses of some drugs taken by a young and an old person result in a higher concentration in the older person.

Regular physical exercise is thought to have many benefits, but it will not build muscle effectively in people over 30. Physically active BLSA volunteers over 30 exhibited no greater muscle mass than their peers who were not physically active. The weight loss and leaner appearance from exercise in middle and old age is apparently due to fat loss. Decreased production of growth hormone, which is a potent factor in building muscle in youth, may be partly responsible for the overall loss in muscle mass with aging.

Loss of muscle mass may account for the gradual loss of muscle strength with age. A decrease in physical performance occurs earlier and to a greater degree when tasks require the coordinated responses of several muscle groups rather than one muscle group, BLSA studies show. For example, static strength of arm and back muscles declines only after age 65 in most healthy people, whereas maximum work rate or cranking begins to fall as early as ages 25 through 30.

Along with a decrease in muscle mass with aging is a lower requirement for calories. BLSA volunteers reported eating less as they grew older. Also, BLSA men reported eating relatively fewer saturated fatty acids and more polyunsaturated fatty acids during the years of the study. Although there was a striking drop in serum cholesterol levels in subjects of all ages, it was not directly associated with a change in thetype of fat eaten. BLSA men showed the general age pattern of low serum cholesterol in the early adult years, reaching a height in middle age, and lower values again in later life. In studies of this kind, true aging effects may be complicated by changes in lifestyle over time. In coming years, scientists will evaluate further changes in this important blood constituent.

Basic personality features do not change significantly with age and are not influenced greatly by life changes among healthy individuals, according to BLSA studies. Although the incidence of health problems increases with age, older persons in the longitudinal study did not complain more about their health than younger persons. When older people did complain, most of their problems dealt with the sensory, cardiovascular, or genitourinary systems--which are most susceptible to age-related disease and disability. Excessive health complaints among BLSA volunteers were associated with poor psychological adjustment. The proportion of such individuals in old age, however, appears to be no higher than it is in the young or middle-aged population.

Common beliefs that older people cannot adapt to stressful situations, that they are rigid or deal ineffectively with reality, proved untrue in BLSA studies. Volunteers completed questionnaires describing how they coped with a recent stressful event such as death of someone close or personal or family illness. Their answers show that older BLSA subjects cope in much the same way as younger subjects do. When they use different ways to cope, it seems to be in response to situations more frequently found in older rather than in younger people, such as general loss of health.

Women and Aging

Studies on women have expanded rapidly since women were added to the BLSA in 1978. General findings which already have emerged, show that female volunteers develop the age-related thickening of the heart wall and slowing of ventricular filling that has been observed in males. Women also lose muscle mass at about the same rate as men in middle age and after. Oxygen consumption at rest seems to decline in both sexes with age and the rate of decline in premenopausal women is similar to that for men. In postmenopausal women, however, the decline is half the rate for men.

Saliva flow and taste sensitivity do not change dramatically with age in healthy, nonmedicated women and men. The taste decrements which do occur usually are specific to certain taste qualities, such as a decreased sensitivity to salt. Individuals on medication--especially postmenopausal women--have decreased saliva flow.

BLSA studies are underway to determine how nutrition, drugs, exercise, hormone changes at menopause, and other factors, might affect the strength and density of bones and the developent of osteoarthritis (degenerative joint disease) and osteoporosis (severe bone loss). These diseases are especially common in older women, can be painful and crippling in their later stages and are significant causes of disability among the elderly.

Little is known about how female sexuality may change with menopause or with age and how physiological, psychological and social factors affect sexual functioning. Since 1982, over 100 BLSA women have completed personal interviews about sexual behavior and attitudes. As more interviews are completed and the data are analyzed, investigators hope to have a base for determining normal female sexual function at different ages.

Conclusion

Enormous advances in medical science over the last 25 years have enabled BLSA and other investigators to uncover increasingly complex mechanisms underlying human aging. Many important questions remain. The basic biological causes of aging are largely unknown and there are many questions about why women live an average of seven to eight years longer than men. The search continues for the causes of functional declines with aging and for the reasons certain diseases occur more frequently with advancing age. Scientists with the BLSA and with other NIA studies at the Gerontology Research Center and in many research institutions across the country, are searching for the answers to these and other questions. Their common goals are to help extend the healthy, productive middle years and to improve the quality of life for older Americans.

Nathan Shock "Historical Origins of the Study" Program for the Silver Anniversary Symposium Letter from President Reagan, Dated - 07/07/83 The NIH Record - 10/25/83 Silver Anniversary

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