The health status of racial and ethnic minority groups in the U.S. has improved steadily over the last century. Despite such progress, disturbing disparities in health persist between majority and minority populations. In 1997, for example, average life expectancy at age 65 was 16.1 years for African Americans and 17.8 years for Caucasians. Demographic projections predict a substantial change in the racial and ethnic makeup of the older population, heightening the need to examine and reduce differences in health and life expectancy. Research to date has shown that health disparities are associated with a broad, complex, and interrelated array of factors. Disease risk, diagnosis, progression, response to treatment, caregiving, and overall quality of life each may be affected by variables such as race, ethnicity, gender, socioeconomic status, age, education, occupation, country of origin, and possibly other lifetime and lifestyle differences. Understanding these relationships will require a thoughtful program of research. Toward that end, the NIA recently completed a year-long review of these issues and developed a strategic plan to address health disparities in the older population. The plan covers fiscal years 2000 to 2005 and sets goals for research, research training, research resources, and dissemination of health information, and attention is paid to health disparities across the full spectrum of NIA-supported research. This part of the narrative looks at selected research advances in AD, menopause, and osteoarthritis that are adding to knowledge about health in various groups. It also describes future research directions for reducing health disparities in the U.S.
AD in the African American Community
While the incidence and prevalence of AD generally and in specific groups remains to be clarified, a few reports have suggested that racial and ethnic minorities might be at greater risk of AD. Research on AD in special populations looks at a number of factors, two of which are described below:
Potential Environmental Risk Factors for AD in African Americans. Socioeconomic or environmental variables may affect the risk of developing AD, even within racial or ethnic groups. Alongitudinal study of dementia and AD in a group of older African Americans included analysis of such variables, examining the effect of level of education and rural vs. urban childhood environment as potential risk factors for AD. For individuals who grew up in an urban setting, low education did not increase the risk of AD significantly. However, for those with rural residence to age 19, low education was a significant risk factor for the disease. Such studies are part of a growing body of research suggesting a link between socioeconomic or environmental variables and risk of developing AD.
Cholesterol May Be a Modifiable Environmental Risk Factor for AD. TheAPOE-ε4 allele, a form of the APOE gene, is a risk factor for development of AD in most populations; however, its role in the risk of AD among African Americans is unclear. APOE also plays a role in cholesterol transport and studies have suggested an interaction among serum cholesterol, APOE status, and AD. This interaction recently was evaluated in a group of older African Americans. Increasing total cholesterol was associated with increased AD risk in the group with no APOE-ε4 alleles, but total cholesterol was not associated with increased AD risk in the group with one or two ε4 alleles. The study results suggest that cholesterol may be a potentially modifiable risk factor for AD in some African Americans who do not carry any APOE-ε4 alleles. Interestingly, this is consistent with recent animal studies indicating that a high cholesterol diet may increase the levels of beta amyloid plaques in brains of transgenic mouse models of AD.
Racial/Ethnic Disparities in Women's Health
Menopause Symptoms in a Multiracial/Ethnic Population of Women. The Study of Women Across the Nation (SWAN) is a prospective longitudinal examination of the natural history of menopause in a large multiracial/ethnic sample of women, age 40–55. Participants include African American, non-Hispanic Caucasian, Chinese, Japanese, and Hispanic women. A survey of SWAN participants identified relationships between reported symptoms of menopause (including hot flashes and night sweats, heart pounding, urine leakage, and forgetfulness) and demographic and lifestyle factors (such as socioeconomic status, education level, difficulty paying for basic items, smoking behavior, body mass index and physical activity). Generally higher reporting levels for specific menopausal symptoms were associated with low socioeconomic status, smoking, low physical activity, and being overweight. The reporting of specific menopausal symptoms varied significantly among racial/ethnic and socioeconomic groups and by lifestyle. Scientists point out that research in this area may provide guidance to health care providers in assessing symptoms by increasing their sensitivity to racial and ethnic differences in reporting symptoms.
Knee Osteoarthritis More Prevalent in Younger African American Women. A recent study in women age 28–52 found that osteoarthritis (OA) of the hand and knee is common after the age of 40, and OA develops between 35 and 40 years for both African-American and Caucasian women. Knee OA was much more frequent in African-American women compared with white women of the same age. The frequency of hand OA was similar between African American and white women. This study provides evidence that primary prevention of OA might need to be attempted in young adulthood. And the striking difference observed in prevalence of knee OA between African-American and white women points to a need to identify factors that might contribute to the African Americans' increased risk of developing OA.
Selected Future Directions in Research on Health Disparities
Reducing Health Disparities. It is estimated that the percentage of racial minorities and Hispanics in the population of Americans over the age of 65 will increase from 16% in the year 2000 to about 36% in 2050.11
Although an array of factors has been associated with health disparities—including race, ethnicity, gender, genetics, socioeconomic status, age, education, and occupation—further research is needed to identify the factors involved in these differences. Research at the NIA-supported Resource Centers on Minority Aging Research and other activities are underway to address a range of measurement issues in the study of multiracial and multiethnic populations. As this basic work moves ahead, new NIA studies will focus on the influence of early and midlife health, nutrition, education, social and cultural factors and health care on the health of older people. Research will also expand understanding of how to prevent or lessen the effects of disease by designing more culturally appropriate interventions and modes of health information dissemination and by discovering means to enhance healthy behaviors in older racial and ethnic populations.
Specifically, there is urgency in identifying genetic and nongenetic risk and protective factors for age-related cognitive decline, AD, and other neurodegenerative diseases of aging in racially and ethnically diverse populations. The NIA is stimulating research on several fronts: to assess and compare prevalence and incidence rates for mild cognitive impairment and AD among different ethnic subgroups, using culturally appropriate instruments; to determine the importance of particular genetic risk and protective factors as well as potential nongenetic risk factors, including comorbid conditions such as cardiovascular and cerebrovascular disease; and to identify differences in factors conferring risk or protection, such as early development, diet, and education.
- Federal Interagency Forum on Aging Related Statistics. Older Americans 2000: Key Indicators of Well-Being. 2000.