Ann Otol 88 :1979
lIEARINC AND ACE RESEARCH CHALLENGES AND THE NATIONAL INSTITUTE ON AGING
ROBERT
N.
BUTLER,
BARBARA CASTEL,
MD
MD, MPH
BETHESDA, ~ARYLAND
Just as the ear trumpet once symbolized the elderly, so do contemporary approaches to hearing loss in the aged reflect many of the major themes in geriatrics and gerontology today. This paper begins by describing the National Institute on Aging (NIA) with particular emphasis on activities relevant to hearing in the elderly. Next, several areas of research interest, including the typology of presbycusis and related conditions, the epidemiology of auditory impairment in old age, the design of testing and research, and the rehabilitation of the hearingimpaired elderly, are addressed. The NIA and the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS) are coordinating their efforts to stimulate investigation of these and related topics.
Hearing impairment is a frequent feature in stereotypes of the aged in our society. A well-known children's song portrays an old woman as hearing only what she wants to hear; she claims to be nearly deaf when asked if she likes to cook and clean, but her hearing suddenly improves when she receives a marriage proposal. The elderly character with ear trumpet in hand often appears in literature and drama. Even the advertising industry employs this image, as its scripts use questions from the hard-ofhearing aged as cues to repeat key information. In science and medicine as in popular culture, our views of hearing loss in the elderly often have reflected prevailing concepts of aging. Likewise, contemporary approaches to gerontology and geriatrics can enhance our understanding and management of hearing impairments in the elderly. Therefore, we shall discuss current concepts of aging, particularly as they relate to the need for research on hearing. Although we are not otologists and therefore will not dwell on the technical aspects of presbycusis and other disorders, we hope that the observations that we bring from the field of aging will stimulate interest, clinical sensitivity, and research.
NIA AND HEARING
Before addressing specific concepts of aging and particular research needs, we would like briefly to describe the National Institute on Aging (NIA) and its activities, especially as they relate to hearing. The NIA, one of the 11 National Institutes of Health (NIH), was established by Congress in 1974 for the "conduct and support of biomedical, social and behavioral research and training related to the aging process and the diseases and other special problems and needs of the aged." The NIA emphasizes extending the healthy middle years of life and increasing the quality of life. In this respect, attention to age-associated hearing impairments is particularly appropriate-for although hearing loss is not a direct cause of death, it can profoundly diminish the quality of life of the aged. A major impetus for the establishment of the NIA was the striking increase in both proportion and total number of elderly in this country. In 1900, only 3.1 million Americans, or 4% of the population, were over age 65. At present, individuals over age 65 number 24 million and constitute 11% of the population. The Bureau of the Census predicts that by the year 2030 this age group will
From the National Institute on Aging, National Institutes of Health, Bethesda, Maryland. Presented at the meeting of the American Otologicai Society, Inc., Los Angeles, California, March 31-April 1, 1979.
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HEARiNG AND AGE: RESEARCH AND NIA
number 52 million and represent 13 to 21% of this country's people.' Thus, as the post-World War II baby boomgro~s gray, hearing loss is likely to assume Illcreasing magnitude. As stipulated by Congress when it created NIA, one of the Institute's initial activities was the establishment of a research plan on aging. This plan" is based on reports submitted by three panels of experts. Two of the three panel reports, those on biomedical research" and on behavioral and social sciences research,' note that hearing loss is a significant problem for the aged and call for research on this topic. Interest in hearing is evident in various NIA research programs. The NIA currently conducts most of its intramural research at the Gerontology Research Center (GRC) in Baltimore. Among the main projects at GRC is the Baltimore Longitudinal Study of Aging, in which 650 male volunteers have undergone extensive batteries of tests every year to two years since 1958; women joined the study in 1978. The tests performed !TIelude audiometry, the results of which are now being analyzed cross-sectionally, longitudinally, and in relation to findings on tests of cognitive function. In addition, scientists at the GRC have studied dichotic listening cross-sectionally in longitudinal study participants and are beginning to collect longitudinal data on performance on this task. The Extramural and Collaborative Research Program (ECRP) of the NIA fosters research on aging at universities, hospitals, medical centers, and o~er institutions throughout the Umted States. It currently sponsors several animal studies related to hearing loss in old age. One such project uses electrophysiological techniques and histological examination to study auditory deficits in aging mice, which exhibit high-frequency hearing loss and cochlear changes similar to those commonly seen in humans with presbycusis; it explores the interaction of genotype with environmental factors such as noise and ototoxic drugs. Another group of researchers is measuring hearing in rats and examining their cochleas and brains. Other areas of research sponsored by the NIA may also directly or indirectly eontrib-
677
ute to our understanding and management of hearing impairment in the aged. For example, studies of the molecular and cellular biology of aging may help to elucidate the fundamental ~ech anisms of some forms of presbycusis; the establishment of animal models and resources is basic to a wide range of experiments regarding hearing and aging; and research on pharmacology in the aged may help to identify ototoxic drugs and perhaps even develop agents that prevent or alleviate presbycusis. This year, the NIA will begin granting Geriatric Medicine Academic Awards to schools of medicine and osteopathy. These awards have the dual purpos~ of impro~ing the quality. of curricula in genatncs and fostering research and careers in the field of aging. Likewise, in part through the encouragement and advice of the NIA, the Health Resources Administration has established Curriculum Development Grants in Geriatrics. These latter grants may be used to facilitate the training of a wide variety of health professionals, including physicians, nurses, audiologists, and many others. The two programs are intended to provide future health professionals with greater sensitivity to and knowledge of various age-associated problems including those related to hearing. The NIA also has established an Epidemiology, Demography, and Biometry Program (EDBP). Among the many topics being addressed are nutrition, systolic hypertension, senile dementia, and the use of estrogens by postmenopausal women. The EDBP is particularly interested in reexamination of the older cohorts previously studied in the first Health and Nutrition Examination Survey (HANES I), which the National Center for Health Statistics conducted in the years 1971 and 1972. The possibility of repeating audiometry in the follow-up study now is being discussed. Because aging is a field about which both professionals and the public generally know little and about which myths abound, dissemination of information is a particularly important activity of the NIA. Thus, this Institute is fortunate to have an especially active information office. In recent months,
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the office has greatly increased its collection of literature on the hearing problems of the aged and thus is able to provide effective responses to a wide range of inquiries about this topic. In pursuing its mission, the NIA often collaborates with other NIH components including those concerned with specific groups of diseases; with other federal agencies; and with organizations outside of government. Later this year, the Institute plans to join with the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS), which also has an active program on the hearing problems of the aged, in sponsoring a seminar on this topic. TOWARD A TYPOLOGY OF AGE-ASSOCIATED HEARING LOSS
The characterization and differentiation of age-related processes is a common task in geriatrics. Merely affixing the adjective "senile" or the prefix "presby-" to the term for a condition does not explain the disorder; it merely states that it characteristically occurs in old age. A classic example is "senility," a term popularly used to denote cognitive dysfunction with onset in old age. Actually, at least 100 different causes exist for such symptoms, which in many instances are reversible if the underlying condition is promptly diagnosed and properly treated. Presbycusis, a term with many spellings and even more definitions, presents similar considerations. This word generally means hearing loss that appears attributable to aging alone; it does not specify the mechanism of such deterioration. Thus, this condition includes at least four types of auditory defects, each of which seems to reflect a characteristic anatomic change and each of which can occur alone or in combination with any of the others." Greater distinction of the disorders included within presbycusis and study of the mechanisms associated with each are important to establishing a typology of hearing loss in old age. A related aspect is the need to distinguish changes intrinsic to aging from those resulting from systemic disorders. This problem often arises in geriatrics; for example, senile dementia must be
differentiated from cognitive changes secondary to heart failure, sepsis, and electrolyte imbalance. Studies suggesting that hearing loss may result from diabetes mellitus? and chronic cardiovascular disease,' both of which are common in the aged, indicate the need for similar care in establishing diagnostic categories. This possible association of hearing impairment with both diabetes and cardiovascular disease suggests that vascular mechanisms may playa major role in some cases of age-associated hearing loss, a hypothesis that deserves further study. Another facet is the distinction of treatable local conditions from irreversible age-related changes. Although the relative and absolute importance of chronic otitis media decreases considerably from childhood to old age, this condition nevertheless deserves consideration. Because of the importance of identifying easily remediable conditions, even a matter as mundane as preventing, diagnosing, and treating accumulations of cerumen, merits attention. A recurrent need throughout geriatrics is the differentiation of changes fundamental to the aging process from those resulting from a lifetime of environmental stresses. This dilemma arises in considering not only such killer diseases as cancer and myocardial infarction but also in constructing a typology of age-associated hearing loss. Attention to environmentally induced changes is particularly important because such knowledge is essential to prevention of unnecessary hearing loss. One recurrent question is the effect of lifelong occupational and recreational exposure to noise on hearing in old age. Another is the cumulative effect of medicationsincluding aspirin, antibiotics such as the aminoglycosides, certain common diuretics, antitumor agents, and other medications of known ototoxicity, as well as drugs with otological effects that remain unknown. The impact of medication is especially relevant, as the 11% of our population above age 65 receives 25% of all prescription drugs dispensed. Many of the 38% of the elderly population who have arthritis undoubtedly consume large quantities of aspirin, and the increases in hypertension and heart failure with age signify a heightened
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HEARING AND AGE: RESEARCH AND NIA
probability of diuretic use. Furthermore, half of all new cases of cancer, and much of the use of chemotherapeutic agents, occur in persons aged 65 and above. At both the NIA and NINCDS, the effect of environment on hearing is an area of considerable research interest, and scientists are correlating the administration of various types and doses of environmental stresses to animals with the resulting losses of hearing and with histological changes in the auditory system. As mentioned previously, one such study examines the interaction of genotype with environmental factors such as noise and ototoxic drugs in mice. Other projects investigate the effects of drugs and industrial noise on monkeys and the impacts of high- and low-cholesterol diets on atherosclerosis and cochlear potentials in pigeons. The typology of hearing disabilities in old age should not be limited to auditory acuity. Other problems to consider include difficulty in understanding speech even when it is sufficiently loud, tinnitus, hypersensitivity to sounds of high intensity, and the loudness recruitment phenomenon. NEED FOR EPIDEMIOLOGIC STUDY
Our knowledge of the epidemiology of many conditions affecting the elderly is incomplete. For example, although senile dementia and cancer may well be the conditions most feared by the aged, we lack data on their precise incidence and prevalence. Likewise, we lack detailed normative data on hearing in old age and do not fully know the prevalence, distribution, correlates, and courses of hearing problems in the elderly. Complicating the problem are a lack of consistency in definitions of hearing loss and in tests used, the select nature of the populations studied and the exclusion of very old subjects, and the often limited techniques used to evaluate hearing. M. Cristina Leske of the State University of New York at Stony Brook has reviewed the prevalence of communicative disorders in the United States. In a report submitted to the NINCDS,8 she notes that the prevalence of hearing impairments rises gradually with age and
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then increases steeply over the age of 60 years, and she cites the following findings. The National Health Examination Survey of 1961-1962, which studied persons 18 to 79 years of age, included pure tone audiometric measurements of hearing threshold levels at six different frequencies. Nearly 30% of persons aged 65 through 74 years and almost half of those aged 75 through 79 years showed elevated hearing levels for speech. In the 1971 National Health Interview Survey, 23% of those 65 through 74 years of age and 40% of those aged 75 and above reported hearing impairments. These surveys provide general estimates of the prevalence of hearing loss but do not characterize the loss by type or cause. More recent epidemiologic surveys also have explored hearing. HANES I, conducted in 1971-1972, included audiometric testing; analysis of data now is in the early stages. Currently unpublished figures from the 1977 Health Interview Survey indicate that 29.3% of persons aged 65 and over reported hearing impairments. Among the most intriguing epidemiologic puzzles concerning the aged is the difference in life expectancy and in the prevalence of various age-associated disorders between men and women. A female born today can expect to live approximately eight years longer than her male counterpart.' and although elderly women have higher rates of such conditions as arthritis, hypertension, and visual impairments, elderly men are more likely to have hearing losses." Perhaps one factor contributing to this difference is the greater rate of exposure to occupational noise by men. Explanation of this difference in hearing might aid in the prevention of auditory impairments and even provide valuable clues into the fundamental sex-related differences in the aging process. An epidemiologic approach also may help to predict hearing loss, as has been attempted in the past/a and thus permit early institution of preventive measures, planning, and rehabilitation. Epidemiologic studies correlating hearing loss with occupation, geographic region, diet, and other factors may prove particularly valuable in this respect.
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DESIGN OF TESTING AND RESEARCH
In studying hearing and other functions in the aged, evaluation of the appropriateness of various test procedures and of the interpretation of test results is necessary. Some approaches that are useful in younger persons may not yield valid results in the aged; one example is the use of acoustic reflex data, which appears to be substantially more accurate in predicting sensorineural hearing level in children than in adults, particularly those in the later years of life." Special measures may be necessary to differentiate hearing loss from cognitive impairment in the elderly who are severely disabled by conditions such as stroke. Furthermore, just as results of the Baltimore Longitudinal Study indicate that normal values on tests of glucose tolerance change with age, norms on certain tests of hearing might be more useful if adjusted for age. Interpretation of the results of any test also should take into account the tendency of elderly persons to behave more cautiously in test situations than younger individuals do; analysis using signal detection theory, a mathematical approach used to separate the influence of sensitivity from that of decisional criteria, can be helpful in this regard." "Stress tests" are commonly used to identify age-associated conditions that may not be apparent under ordinary test circumstances. Two examples from internal medicine are exercise tests to detect coronary insufficiency and glucose tolerance tests to identify diabetes mellitus. Analogous audiological tests, which require the subject to interpret speech that has been degraded in various manners, most clearly demonstrate the effects of aging on the understanding of speech." A related theme is the greater decline in performance on complex tasks with age. Just as the ability to perform a coordinated movement declines faster with age than does muscular strength," so the ability to understand speech often diminishes more rapidly than does the perception of sound." Another valuable approach in studying the aged is the use of longitudinal studies. In the cross-sectional approach, individuals of different ages are compared at a single time; thus, differences
can reflect both age and other factors such as variation in genetic composition, cultural background, level of education, and cohort history. Longitudinal studies, however, control for such variables by reexamining the same subjects repeatedly. This method is particularly useful in establishing the natural course of hearing disorders and studying the factors associated with onsets of hearing loss at different ages. Examples of the longitudinal approach to examining hearing in humans include a study of the perception of degraded speech.> the Baltimore Longitudinal Study, and the proposed repetition of the hearing tests of the HANES I study. Researchers supported by NIA also are studying animals longitudinally to determine the course of changes in hearing and in the structure of the auditory system. Lifelong longitudinal study of individuals with congenital or childhood hearing loss would be useful in determining the course of these disabilities and the resulting problems and thus in intervening more effectively at all ages. CONSIDERATIONS IN REHABILITATION
Rehabilitation is an important consideration throughout geriatrics, whether for the elderly man who has suffered a myocardial infarction, the aged woman recovering from a fractured hip, or the older person with a hearing disability. Just as today colleges and community centers are introducing programs for the elderly, those who rehabilitate the hearing-impaired are beginning to tum their attention to the aged, both in the community and in institutions. Although patience and ingenuity often are necessary, results can be favorable even in a large proportion of institutionalized patients.!" One important factor is an environment in which communication is both necessary and rewarding." Older patients commonly have multiple physical, psychological, and social problems, the interaction of which can complicate the management of various conditions, including hearing loss. For example, an elderly person grieving for a lost spouse or beset by economic difficulties may have little motivation to undergo auditory testing and rehabilitation. Likewise, an older individual who has suffered a stroke or has severe
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HEARlNG AND AGE: RESEARCH AND NIA
arthritis may find insertion of a conventional earmold and adjustment of the usual type of controls on a hearing aid difficult or impossible; and visual impairment can make speech reading difficult. In addition, an older person who is battling cancer or severe cardiovascular disease may consider efforts to improve hearing unimportant. However, attitudes are as varied as older individuals. Some may say or think "I'll die soon anyway, so what's the use?" Others, however, share the attitude of the elderly nursing home resident who told his audiologist, "This home is Grand Central Station, you know. This is the last stop. But I want to make the most of it while I'm here.">' The social, psychological, and cognitive aspects of various physical problems, including hearing loss, are important considerations in approaching therapy. The loneliness, depression, and social isolation that defective hearing can create, as well as the vulnerability of the hearing-impaired elderly to crime and fraud, deserve particular attention in both research and therapy. Likewise, the observed association of hearing impairment with paranoid illness in later life 1 8 merits further study. The specific effects of the interaction of hearing loss with other problems, for example, the increased reaction time associated with decreased auditory acuity in the presence of depression," also need investigation. The reported association of mild hearing losses in the aged with diminished performance on verbal tests of intellectual ability'" is particularly provocative; scientists at the GRC now are exploring this relationship by analyzing auditory and cognitive data from the Baltimore Longitudinal Study. In devising methods of auditory training for the elderly, all of these factors should be considered. Development of appropriate prostheses is of major concern in many areas of geriatric medicine, and the NIA and the National Aeronautics and Space Administration have an agreement to collaborate in applying technology to help older people with sensory, communicative, and motor disabilities. The aged need hearing aids that not only have proper performance characteristics but also can be inserted and controlled by those
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with concurrent disabilities such as arthritis; one example is an earmold with a handle to facilitate its use by patients with limited finger dexterity." In order to predict the success of cochlear implants, the NINCDS is sponsoring a study that includes assessment of the degree of cochlear nerve degeneration in patients with hearing losses secondary to various factors including aging. Devices that permit the hearing-impaired to communicate by telephone, an especially important consideration for those who live alone, also deserve particular emphasis. In developing prostheses for the aged, we must not be bound by convention. For example, we must investigate whether older persons are somehow embarrassed about hearing loss and thus demand miniaturized prostheses, or whether they would prefer larger devices that are more effective and easier to use. In 1977, Dr. J. J. Groen, a distinguished internist from the Netherlands, visited the NIA and demonstrated the large apparatus that he had assembled to compensate for his own severe age-related hearing impairment; he noted that expecting excellent results from a miniaturized hearing aid is as unrealistic as anticipating fine reception from a tiny transistor radio. Dr. Groen's apparatus, which resembles that used in some schools for the deaf, includes an excellent set of earphones, a fine microphone that can be positioned as needed, and an adjustable high-quality amplifier. Dr. Groen stated that his special apparatus totally corrects his hearing defect in virtually all situations, whereas without it he would have become a "handicapped invalid." Clearly, such approaches demand attention. The American Humane Association now is training dogs to serve as "hearing dogs," which are analogous to seeingeye dogs. These animals signal to their owners to indicate such events as a sounding alarm, a ringing telephone or doorbell, or a honking car. 22 Such an approach is not necessary for most hearing-impaired older individuals, who retain some degree of hearing. However, ''hearing dogs" may prove a valuable source of aid, companionship, and protection to the elderly who have complete hearing losses and live alone.
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Various problems of the aged require a team approach. In the diagnosis and management of hearing impairment in the elderly, this team may include primary care physicians, otologists, audiologists, nurses, hearing aid distributors, social workers, mental health workers, and nursing home personnel. Family members and others with whom the patient spends much time are essential members of the team and should receive guidance in interacting effectively with the hearing-impaired. Improvement of the team approach to the hearing problems of the elderly requires further investigation. FUTURE DIRECTIONS
Hearing loss in the aged thus presents many challenges for research. Staff from the NIA and NINCDS have been discussing this important matter for nearly three years, and later this year the two Institutes will jointly sponsor a seminar on hearing and the aged. Leading experts will discuss five major aspects: epidemiology, including the gaps in our knowledge and how to fill them; dif-
ferential diagnosis, including development of diagnostic methods for patients unable to communicate; treatment, including medical and nonmedical approaches; long-term management, including collaboration of family members, control of psychological effects, and modification of the environment; and the development of effective, appropriate prostheses. The seminar will culminate in a publicly distributed report containing recommendations for research on hearing and the aged. Both Institutes hope that increased attention to this important field will follow. In summary, the hearing impairments commonly included in stereotypes of the aged may not be fully accurate, but the grain of truth is considerable. The ear trumpet once symbolized the elderly, but now our approaches to hearing loss must reflect new outlooks on aging. Investigation of the communicative disorders of the aged must combine the concepts and tools of researchers in hearing with the perspectives of gerontology and geriatrics.
REFERENCES 1. Siegel JS: Demographic Aspects of Aging and the Older Population in the United States, Current population reports: Special studies: Series P-23, No. 59. Washington, US Government Printing Office, 1978 2. Our Future Selves: A Research Plan Toward Understanding Aging, DHEW Publication No. 77-1096. Washington, US Government Printing Office, 1977 3. Our Future Selves: A Research Plan Toward Understanding Aging. Report of the Panel on Biomedical Research, DHEW Publication No. (NIH) 78-1445. Washington, US Government Printing Office, 1978 4. Our Future Selves: A Research Plan Toward Understanding Aging. Report of the Panel on Behavioral and Social Sciences Research, DHEW Publication No. (NIH) 781444. Washington, US Government Printing Office, 1978 5. Committee on Hearing, Bioacoustics and Biomechanics: Speech Understanding and Aging. Washington, National Academy of Sciences, 1977 6. Taylor IG, Irwin J: Some audiological aspects of diabetes mellitus. J Laryngol Otol 92:99-113, 1978 7. Rubinstein M, Hildesheimer M, Zohar S, et al: Chronic cardiovascular pathology and hearing loss in the aged. Gerontology 23:4-9, 1977 8. Leske MC: Prevalence estimates of
communicative disorders in the US. Report prepared for the National Institute of Neurological and Communicative Disorders and Stroke, 1978 9. Kovar MG: Elderly people: the population 65 years and over, in: Health, United States 1976-1977. DHEW Publication No. (HRA) 77-1232, Washington, US Government Printing Office, 1977 10. Pearson JCG: Prediction of presbycusis. J Soc Occup Med 27: 125-133, 1977 11. Jerger J, Hayes D, Anthony L: Effect of age on prediction of sensorineural hearing level from the acoustic reflex. Arch Otolaryngol, 104:393-394, 1978 12. Potash M, Jones B: Aging and decision criteria for the detection of tones in noise. J Gerontol 32:436-440, 1977 13. Norris AH, Shock NW: Age and the physiological responses to exercise, in: Dasco MM (ed ): Proceedings of the Research Conference on Applied Work Physiology, Tuxedo Park, NY, April 10-11, 1968. New York, New York University Medical Center, 1969, pp 235-263 14. Bergman M, Blumenfeld VG, Cascardo D, et al: Age-related decrement in hearing for speech. Sampling and longitudinal studies. J Gerontol 31 :533-538, 1976 15. Smith CR, Fay TH: A!rogram of auditory rehabilitation for age persons in a
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HEARING AND AGE: RESEARCH AND N1A chronic disease hospital. ASHA 19:417-420, 1977 16. Alpiner JG: Rehabilitation of the geriatric client, in Alpiner JG (ed ): Handbook of Adult Rehabilitative Audiology. Baltimore, Williams and Wilkins, 1978 17. Schow RL, Christensen JM, Hutchinson JM, et al: Communication Disorders of the Aged. A Guide for Health Professionals. Baltimore, University Park Press, 1978, p 331 18. Cooper AF, Curry AR: The pathology of deafness in the paranoid and affective psychoses of later life. J Psychosom Res 20; 97105, 1976 19. Birren JE, Butler RN, Greenhouse SW, et aI: Interdisciplinary relationships: Interre-
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lations of physiological, psychological, and psychiatric findings, in healthy elderly men, in Birren JE, Butler RN, Greenhouse SW, et al (eds): Human Aging I. A Biological and Behavioral Study, DHEW Publication No. (ADM) 77-122. Washington, US Government Printing Office, 1976 20. Granick S, Kleban MH, Weiss AD: Relationships between hearing loss and cognition in normally hearing aged persons. J Gerontol 31:434-440, 1976 21. Navarro MR: An earmold for the geriatric patient. J Speech Hear Disord 42:44-46, 1977 22. Crowley S: Man's best friend provides an ear to the world for the deaf. Washington Post: February 8, 1979, p DC8
REPRINTS Robert N. Butler, MD, Director, National Institute on Aging, National Institutes of Health, Bethesda, MD 20205.
ASSOCIATION FOR RESEARCH IN OTOLARYNGOLOGY The Annual Midwinter Meeting of the Association for Research in Otolaryngology will take place January 21-23, 1980 at the Happy Dolphin Inn, St. Petersburg, FL. Persons wishing to register should contact Josef M. Miller, PhD, Secretary-Treasurer, University of Washington, RL-30, Seattle, WA 98195.
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lIEARINC AND ACE RESEARCH CHALLENGES AND THE NATIONAL INSTITUTE ON AGING
ROBERT
N.
BUTLER,
BARBARA CASTEL,
MD
MD, MPH
BETHESDA, ~ARYLAND
Just as the ear trumpet once symbolized the elderly, so do contemporary approaches to hearing loss in the aged reflect many of the major themes in geriatrics and gerontology today. This paper begins by describing the National Institute on Aging (NIA) with particular emphasis on activities relevant to hearing in the elderly. Next, several areas of research interest, including the typology of presbycusis and related conditions, the epidemiology of auditory impairment in old age, the design of testing and research, and the rehabilitation of the hearingimpaired elderly, are addressed. The NIA and the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS) are coordinating their efforts to stimulate investigation of these and related topics.
Hearing impairment is a frequent feature in stereotypes of the aged in our society. A well-known children's song portrays an old woman as hearing only what she wants to hear; she claims to be nearly deaf when asked if she likes to cook and clean, but her hearing suddenly improves when she receives a marriage proposal. The elderly character with ear trumpet in hand often appears in literature and drama. Even the advertising industry employs this image, as its scripts use questions from the hard-ofhearing aged as cues to repeat key information. In science and medicine as in popular culture, our views of hearing loss in the elderly often have reflected prevailing concepts of aging. Likewise, contemporary approaches to gerontology and geriatrics can enhance our understanding and management of hearing impairments in the elderly. Therefore, we shall discuss current concepts of aging, particularly as they relate to the need for research on hearing. Although we are not otologists and therefore will not dwell on the technical aspects of presbycusis and other disorders, we hope that the observations that we bring from the field of aging will stimulate interest, clinical sensitivity, and research.
NIA AND HEARING
Before addressing specific concepts of aging and particular research needs, we would like briefly to describe the National Institute on Aging (NIA) and its activities, especially as they relate to hearing. The NIA, one of the 11 National Institutes of Health (NIH), was established by Congress in 1974 for the "conduct and support of biomedical, social and behavioral research and training related to the aging process and the diseases and other special problems and needs of the aged." The NIA emphasizes extending the healthy middle years of life and increasing the quality of life. In this respect, attention to age-associated hearing impairments is particularly appropriate-for although hearing loss is not a direct cause of death, it can profoundly diminish the quality of life of the aged. A major impetus for the establishment of the NIA was the striking increase in both proportion and total number of elderly in this country. In 1900, only 3.1 million Americans, or 4% of the population, were over age 65. At present, individuals over age 65 number 24 million and constitute 11% of the population. The Bureau of the Census predicts that by the year 2030 this age group will
From the National Institute on Aging, National Institutes of Health, Bethesda, Maryland. Presented at the meeting of the American Otologicai Society, Inc., Los Angeles, California, March 31-April 1, 1979.
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number 52 million and represent 13 to 21% of this country's people.' Thus, as the post-World War II baby boomgro~s gray, hearing loss is likely to assume Illcreasing magnitude. As stipulated by Congress when it created NIA, one of the Institute's initial activities was the establishment of a research plan on aging. This plan" is based on reports submitted by three panels of experts. Two of the three panel reports, those on biomedical research" and on behavioral and social sciences research,' note that hearing loss is a significant problem for the aged and call for research on this topic. Interest in hearing is evident in various NIA research programs. The NIA currently conducts most of its intramural research at the Gerontology Research Center (GRC) in Baltimore. Among the main projects at GRC is the Baltimore Longitudinal Study of Aging, in which 650 male volunteers have undergone extensive batteries of tests every year to two years since 1958; women joined the study in 1978. The tests performed !TIelude audiometry, the results of which are now being analyzed cross-sectionally, longitudinally, and in relation to findings on tests of cognitive function. In addition, scientists at the GRC have studied dichotic listening cross-sectionally in longitudinal study participants and are beginning to collect longitudinal data on performance on this task. The Extramural and Collaborative Research Program (ECRP) of the NIA fosters research on aging at universities, hospitals, medical centers, and o~er institutions throughout the Umted States. It currently sponsors several animal studies related to hearing loss in old age. One such project uses electrophysiological techniques and histological examination to study auditory deficits in aging mice, which exhibit high-frequency hearing loss and cochlear changes similar to those commonly seen in humans with presbycusis; it explores the interaction of genotype with environmental factors such as noise and ototoxic drugs. Another group of researchers is measuring hearing in rats and examining their cochleas and brains. Other areas of research sponsored by the NIA may also directly or indirectly eontrib-
677
ute to our understanding and management of hearing impairment in the aged. For example, studies of the molecular and cellular biology of aging may help to elucidate the fundamental ~ech anisms of some forms of presbycusis; the establishment of animal models and resources is basic to a wide range of experiments regarding hearing and aging; and research on pharmacology in the aged may help to identify ototoxic drugs and perhaps even develop agents that prevent or alleviate presbycusis. This year, the NIA will begin granting Geriatric Medicine Academic Awards to schools of medicine and osteopathy. These awards have the dual purpos~ of impro~ing the quality. of curricula in genatncs and fostering research and careers in the field of aging. Likewise, in part through the encouragement and advice of the NIA, the Health Resources Administration has established Curriculum Development Grants in Geriatrics. These latter grants may be used to facilitate the training of a wide variety of health professionals, including physicians, nurses, audiologists, and many others. The two programs are intended to provide future health professionals with greater sensitivity to and knowledge of various age-associated problems including those related to hearing. The NIA also has established an Epidemiology, Demography, and Biometry Program (EDBP). Among the many topics being addressed are nutrition, systolic hypertension, senile dementia, and the use of estrogens by postmenopausal women. The EDBP is particularly interested in reexamination of the older cohorts previously studied in the first Health and Nutrition Examination Survey (HANES I), which the National Center for Health Statistics conducted in the years 1971 and 1972. The possibility of repeating audiometry in the follow-up study now is being discussed. Because aging is a field about which both professionals and the public generally know little and about which myths abound, dissemination of information is a particularly important activity of the NIA. Thus, this Institute is fortunate to have an especially active information office. In recent months,
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the office has greatly increased its collection of literature on the hearing problems of the aged and thus is able to provide effective responses to a wide range of inquiries about this topic. In pursuing its mission, the NIA often collaborates with other NIH components including those concerned with specific groups of diseases; with other federal agencies; and with organizations outside of government. Later this year, the Institute plans to join with the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS), which also has an active program on the hearing problems of the aged, in sponsoring a seminar on this topic. TOWARD A TYPOLOGY OF AGE-ASSOCIATED HEARING LOSS
The characterization and differentiation of age-related processes is a common task in geriatrics. Merely affixing the adjective "senile" or the prefix "presby-" to the term for a condition does not explain the disorder; it merely states that it characteristically occurs in old age. A classic example is "senility," a term popularly used to denote cognitive dysfunction with onset in old age. Actually, at least 100 different causes exist for such symptoms, which in many instances are reversible if the underlying condition is promptly diagnosed and properly treated. Presbycusis, a term with many spellings and even more definitions, presents similar considerations. This word generally means hearing loss that appears attributable to aging alone; it does not specify the mechanism of such deterioration. Thus, this condition includes at least four types of auditory defects, each of which seems to reflect a characteristic anatomic change and each of which can occur alone or in combination with any of the others." Greater distinction of the disorders included within presbycusis and study of the mechanisms associated with each are important to establishing a typology of hearing loss in old age. A related aspect is the need to distinguish changes intrinsic to aging from those resulting from systemic disorders. This problem often arises in geriatrics; for example, senile dementia must be
differentiated from cognitive changes secondary to heart failure, sepsis, and electrolyte imbalance. Studies suggesting that hearing loss may result from diabetes mellitus? and chronic cardiovascular disease,' both of which are common in the aged, indicate the need for similar care in establishing diagnostic categories. This possible association of hearing impairment with both diabetes and cardiovascular disease suggests that vascular mechanisms may playa major role in some cases of age-associated hearing loss, a hypothesis that deserves further study. Another facet is the distinction of treatable local conditions from irreversible age-related changes. Although the relative and absolute importance of chronic otitis media decreases considerably from childhood to old age, this condition nevertheless deserves consideration. Because of the importance of identifying easily remediable conditions, even a matter as mundane as preventing, diagnosing, and treating accumulations of cerumen, merits attention. A recurrent need throughout geriatrics is the differentiation of changes fundamental to the aging process from those resulting from a lifetime of environmental stresses. This dilemma arises in considering not only such killer diseases as cancer and myocardial infarction but also in constructing a typology of age-associated hearing loss. Attention to environmentally induced changes is particularly important because such knowledge is essential to prevention of unnecessary hearing loss. One recurrent question is the effect of lifelong occupational and recreational exposure to noise on hearing in old age. Another is the cumulative effect of medicationsincluding aspirin, antibiotics such as the aminoglycosides, certain common diuretics, antitumor agents, and other medications of known ototoxicity, as well as drugs with otological effects that remain unknown. The impact of medication is especially relevant, as the 11% of our population above age 65 receives 25% of all prescription drugs dispensed. Many of the 38% of the elderly population who have arthritis undoubtedly consume large quantities of aspirin, and the increases in hypertension and heart failure with age signify a heightened
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probability of diuretic use. Furthermore, half of all new cases of cancer, and much of the use of chemotherapeutic agents, occur in persons aged 65 and above. At both the NIA and NINCDS, the effect of environment on hearing is an area of considerable research interest, and scientists are correlating the administration of various types and doses of environmental stresses to animals with the resulting losses of hearing and with histological changes in the auditory system. As mentioned previously, one such study examines the interaction of genotype with environmental factors such as noise and ototoxic drugs in mice. Other projects investigate the effects of drugs and industrial noise on monkeys and the impacts of high- and low-cholesterol diets on atherosclerosis and cochlear potentials in pigeons. The typology of hearing disabilities in old age should not be limited to auditory acuity. Other problems to consider include difficulty in understanding speech even when it is sufficiently loud, tinnitus, hypersensitivity to sounds of high intensity, and the loudness recruitment phenomenon. NEED FOR EPIDEMIOLOGIC STUDY
Our knowledge of the epidemiology of many conditions affecting the elderly is incomplete. For example, although senile dementia and cancer may well be the conditions most feared by the aged, we lack data on their precise incidence and prevalence. Likewise, we lack detailed normative data on hearing in old age and do not fully know the prevalence, distribution, correlates, and courses of hearing problems in the elderly. Complicating the problem are a lack of consistency in definitions of hearing loss and in tests used, the select nature of the populations studied and the exclusion of very old subjects, and the often limited techniques used to evaluate hearing. M. Cristina Leske of the State University of New York at Stony Brook has reviewed the prevalence of communicative disorders in the United States. In a report submitted to the NINCDS,8 she notes that the prevalence of hearing impairments rises gradually with age and
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then increases steeply over the age of 60 years, and she cites the following findings. The National Health Examination Survey of 1961-1962, which studied persons 18 to 79 years of age, included pure tone audiometric measurements of hearing threshold levels at six different frequencies. Nearly 30% of persons aged 65 through 74 years and almost half of those aged 75 through 79 years showed elevated hearing levels for speech. In the 1971 National Health Interview Survey, 23% of those 65 through 74 years of age and 40% of those aged 75 and above reported hearing impairments. These surveys provide general estimates of the prevalence of hearing loss but do not characterize the loss by type or cause. More recent epidemiologic surveys also have explored hearing. HANES I, conducted in 1971-1972, included audiometric testing; analysis of data now is in the early stages. Currently unpublished figures from the 1977 Health Interview Survey indicate that 29.3% of persons aged 65 and over reported hearing impairments. Among the most intriguing epidemiologic puzzles concerning the aged is the difference in life expectancy and in the prevalence of various age-associated disorders between men and women. A female born today can expect to live approximately eight years longer than her male counterpart.' and although elderly women have higher rates of such conditions as arthritis, hypertension, and visual impairments, elderly men are more likely to have hearing losses." Perhaps one factor contributing to this difference is the greater rate of exposure to occupational noise by men. Explanation of this difference in hearing might aid in the prevention of auditory impairments and even provide valuable clues into the fundamental sex-related differences in the aging process. An epidemiologic approach also may help to predict hearing loss, as has been attempted in the past/a and thus permit early institution of preventive measures, planning, and rehabilitation. Epidemiologic studies correlating hearing loss with occupation, geographic region, diet, and other factors may prove particularly valuable in this respect.
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In studying hearing and other functions in the aged, evaluation of the appropriateness of various test procedures and of the interpretation of test results is necessary. Some approaches that are useful in younger persons may not yield valid results in the aged; one example is the use of acoustic reflex data, which appears to be substantially more accurate in predicting sensorineural hearing level in children than in adults, particularly those in the later years of life." Special measures may be necessary to differentiate hearing loss from cognitive impairment in the elderly who are severely disabled by conditions such as stroke. Furthermore, just as results of the Baltimore Longitudinal Study indicate that normal values on tests of glucose tolerance change with age, norms on certain tests of hearing might be more useful if adjusted for age. Interpretation of the results of any test also should take into account the tendency of elderly persons to behave more cautiously in test situations than younger individuals do; analysis using signal detection theory, a mathematical approach used to separate the influence of sensitivity from that of decisional criteria, can be helpful in this regard." "Stress tests" are commonly used to identify age-associated conditions that may not be apparent under ordinary test circumstances. Two examples from internal medicine are exercise tests to detect coronary insufficiency and glucose tolerance tests to identify diabetes mellitus. Analogous audiological tests, which require the subject to interpret speech that has been degraded in various manners, most clearly demonstrate the effects of aging on the understanding of speech." A related theme is the greater decline in performance on complex tasks with age. Just as the ability to perform a coordinated movement declines faster with age than does muscular strength," so the ability to understand speech often diminishes more rapidly than does the perception of sound." Another valuable approach in studying the aged is the use of longitudinal studies. In the cross-sectional approach, individuals of different ages are compared at a single time; thus, differences
can reflect both age and other factors such as variation in genetic composition, cultural background, level of education, and cohort history. Longitudinal studies, however, control for such variables by reexamining the same subjects repeatedly. This method is particularly useful in establishing the natural course of hearing disorders and studying the factors associated with onsets of hearing loss at different ages. Examples of the longitudinal approach to examining hearing in humans include a study of the perception of degraded speech.> the Baltimore Longitudinal Study, and the proposed repetition of the hearing tests of the HANES I study. Researchers supported by NIA also are studying animals longitudinally to determine the course of changes in hearing and in the structure of the auditory system. Lifelong longitudinal study of individuals with congenital or childhood hearing loss would be useful in determining the course of these disabilities and the resulting problems and thus in intervening more effectively at all ages. CONSIDERATIONS IN REHABILITATION
Rehabilitation is an important consideration throughout geriatrics, whether for the elderly man who has suffered a myocardial infarction, the aged woman recovering from a fractured hip, or the older person with a hearing disability. Just as today colleges and community centers are introducing programs for the elderly, those who rehabilitate the hearing-impaired are beginning to tum their attention to the aged, both in the community and in institutions. Although patience and ingenuity often are necessary, results can be favorable even in a large proportion of institutionalized patients.!" One important factor is an environment in which communication is both necessary and rewarding." Older patients commonly have multiple physical, psychological, and social problems, the interaction of which can complicate the management of various conditions, including hearing loss. For example, an elderly person grieving for a lost spouse or beset by economic difficulties may have little motivation to undergo auditory testing and rehabilitation. Likewise, an older individual who has suffered a stroke or has severe
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arthritis may find insertion of a conventional earmold and adjustment of the usual type of controls on a hearing aid difficult or impossible; and visual impairment can make speech reading difficult. In addition, an older person who is battling cancer or severe cardiovascular disease may consider efforts to improve hearing unimportant. However, attitudes are as varied as older individuals. Some may say or think "I'll die soon anyway, so what's the use?" Others, however, share the attitude of the elderly nursing home resident who told his audiologist, "This home is Grand Central Station, you know. This is the last stop. But I want to make the most of it while I'm here.">' The social, psychological, and cognitive aspects of various physical problems, including hearing loss, are important considerations in approaching therapy. The loneliness, depression, and social isolation that defective hearing can create, as well as the vulnerability of the hearing-impaired elderly to crime and fraud, deserve particular attention in both research and therapy. Likewise, the observed association of hearing impairment with paranoid illness in later life 1 8 merits further study. The specific effects of the interaction of hearing loss with other problems, for example, the increased reaction time associated with decreased auditory acuity in the presence of depression," also need investigation. The reported association of mild hearing losses in the aged with diminished performance on verbal tests of intellectual ability'" is particularly provocative; scientists at the GRC now are exploring this relationship by analyzing auditory and cognitive data from the Baltimore Longitudinal Study. In devising methods of auditory training for the elderly, all of these factors should be considered. Development of appropriate prostheses is of major concern in many areas of geriatric medicine, and the NIA and the National Aeronautics and Space Administration have an agreement to collaborate in applying technology to help older people with sensory, communicative, and motor disabilities. The aged need hearing aids that not only have proper performance characteristics but also can be inserted and controlled by those
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with concurrent disabilities such as arthritis; one example is an earmold with a handle to facilitate its use by patients with limited finger dexterity." In order to predict the success of cochlear implants, the NINCDS is sponsoring a study that includes assessment of the degree of cochlear nerve degeneration in patients with hearing losses secondary to various factors including aging. Devices that permit the hearing-impaired to communicate by telephone, an especially important consideration for those who live alone, also deserve particular emphasis. In developing prostheses for the aged, we must not be bound by convention. For example, we must investigate whether older persons are somehow embarrassed about hearing loss and thus demand miniaturized prostheses, or whether they would prefer larger devices that are more effective and easier to use. In 1977, Dr. J. J. Groen, a distinguished internist from the Netherlands, visited the NIA and demonstrated the large apparatus that he had assembled to compensate for his own severe age-related hearing impairment; he noted that expecting excellent results from a miniaturized hearing aid is as unrealistic as anticipating fine reception from a tiny transistor radio. Dr. Groen's apparatus, which resembles that used in some schools for the deaf, includes an excellent set of earphones, a fine microphone that can be positioned as needed, and an adjustable high-quality amplifier. Dr. Groen stated that his special apparatus totally corrects his hearing defect in virtually all situations, whereas without it he would have become a "handicapped invalid." Clearly, such approaches demand attention. The American Humane Association now is training dogs to serve as "hearing dogs," which are analogous to seeingeye dogs. These animals signal to their owners to indicate such events as a sounding alarm, a ringing telephone or doorbell, or a honking car. 22 Such an approach is not necessary for most hearing-impaired older individuals, who retain some degree of hearing. However, ''hearing dogs" may prove a valuable source of aid, companionship, and protection to the elderly who have complete hearing losses and live alone.
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Various problems of the aged require a team approach. In the diagnosis and management of hearing impairment in the elderly, this team may include primary care physicians, otologists, audiologists, nurses, hearing aid distributors, social workers, mental health workers, and nursing home personnel. Family members and others with whom the patient spends much time are essential members of the team and should receive guidance in interacting effectively with the hearing-impaired. Improvement of the team approach to the hearing problems of the elderly requires further investigation. FUTURE DIRECTIONS
Hearing loss in the aged thus presents many challenges for research. Staff from the NIA and NINCDS have been discussing this important matter for nearly three years, and later this year the two Institutes will jointly sponsor a seminar on hearing and the aged. Leading experts will discuss five major aspects: epidemiology, including the gaps in our knowledge and how to fill them; dif-
ferential diagnosis, including development of diagnostic methods for patients unable to communicate; treatment, including medical and nonmedical approaches; long-term management, including collaboration of family members, control of psychological effects, and modification of the environment; and the development of effective, appropriate prostheses. The seminar will culminate in a publicly distributed report containing recommendations for research on hearing and the aged. Both Institutes hope that increased attention to this important field will follow. In summary, the hearing impairments commonly included in stereotypes of the aged may not be fully accurate, but the grain of truth is considerable. The ear trumpet once symbolized the elderly, but now our approaches to hearing loss must reflect new outlooks on aging. Investigation of the communicative disorders of the aged must combine the concepts and tools of researchers in hearing with the perspectives of gerontology and geriatrics.
REFERENCES 1. Siegel JS: Demographic Aspects of Aging and the Older Population in the United States, Current population reports: Special studies: Series P-23, No. 59. Washington, US Government Printing Office, 1978 2. Our Future Selves: A Research Plan Toward Understanding Aging, DHEW Publication No. 77-1096. Washington, US Government Printing Office, 1977 3. Our Future Selves: A Research Plan Toward Understanding Aging. Report of the Panel on Biomedical Research, DHEW Publication No. (NIH) 78-1445. Washington, US Government Printing Office, 1978 4. Our Future Selves: A Research Plan Toward Understanding Aging. Report of the Panel on Behavioral and Social Sciences Research, DHEW Publication No. (NIH) 781444. Washington, US Government Printing Office, 1978 5. Committee on Hearing, Bioacoustics and Biomechanics: Speech Understanding and Aging. Washington, National Academy of Sciences, 1977 6. Taylor IG, Irwin J: Some audiological aspects of diabetes mellitus. J Laryngol Otol 92:99-113, 1978 7. Rubinstein M, Hildesheimer M, Zohar S, et al: Chronic cardiovascular pathology and hearing loss in the aged. Gerontology 23:4-9, 1977 8. Leske MC: Prevalence estimates of
communicative disorders in the US. Report prepared for the National Institute of Neurological and Communicative Disorders and Stroke, 1978 9. Kovar MG: Elderly people: the population 65 years and over, in: Health, United States 1976-1977. DHEW Publication No. (HRA) 77-1232, Washington, US Government Printing Office, 1977 10. Pearson JCG: Prediction of presbycusis. J Soc Occup Med 27: 125-133, 1977 11. Jerger J, Hayes D, Anthony L: Effect of age on prediction of sensorineural hearing level from the acoustic reflex. Arch Otolaryngol, 104:393-394, 1978 12. Potash M, Jones B: Aging and decision criteria for the detection of tones in noise. J Gerontol 32:436-440, 1977 13. Norris AH, Shock NW: Age and the physiological responses to exercise, in: Dasco MM (ed ): Proceedings of the Research Conference on Applied Work Physiology, Tuxedo Park, NY, April 10-11, 1968. New York, New York University Medical Center, 1969, pp 235-263 14. Bergman M, Blumenfeld VG, Cascardo D, et al: Age-related decrement in hearing for speech. Sampling and longitudinal studies. J Gerontol 31 :533-538, 1976 15. Smith CR, Fay TH: A!rogram of auditory rehabilitation for age persons in a
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HEARING AND AGE: RESEARCH AND N1A chronic disease hospital. ASHA 19:417-420, 1977 16. Alpiner JG: Rehabilitation of the geriatric client, in Alpiner JG (ed ): Handbook of Adult Rehabilitative Audiology. Baltimore, Williams and Wilkins, 1978 17. Schow RL, Christensen JM, Hutchinson JM, et al: Communication Disorders of the Aged. A Guide for Health Professionals. Baltimore, University Park Press, 1978, p 331 18. Cooper AF, Curry AR: The pathology of deafness in the paranoid and affective psychoses of later life. J Psychosom Res 20; 97105, 1976 19. Birren JE, Butler RN, Greenhouse SW, et aI: Interdisciplinary relationships: Interre-
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lations of physiological, psychological, and psychiatric findings, in healthy elderly men, in Birren JE, Butler RN, Greenhouse SW, et al (eds): Human Aging I. A Biological and Behavioral Study, DHEW Publication No. (ADM) 77-122. Washington, US Government Printing Office, 1976 20. Granick S, Kleban MH, Weiss AD: Relationships between hearing loss and cognition in normally hearing aged persons. J Gerontol 31:434-440, 1976 21. Navarro MR: An earmold for the geriatric patient. J Speech Hear Disord 42:44-46, 1977 22. Crowley S: Man's best friend provides an ear to the world for the deaf. Washington Post: February 8, 1979, p DC8
REPRINTS Robert N. Butler, MD, Director, National Institute on Aging, National Institutes of Health, Bethesda, MD 20205.
ASSOCIATION FOR RESEARCH IN OTOLARYNGOLOGY The Annual Midwinter Meeting of the Association for Research in Otolaryngology will take place January 21-23, 1980 at the Happy Dolphin Inn, St. Petersburg, FL. Persons wishing to register should contact Josef M. Miller, PhD, Secretary-Treasurer, University of Washington, RL-30, Seattle, WA 98195.
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