Studies and surveys suggest that certain racial, ethnic, and socioeconomic groups may be at greater risk than others for cognitive decline and dementia, and that different groups are vulnerable to different risk factors. Understanding these differences is critical to developing appropriate risk assessments and diagnostic tools and providing the most effective interventions to minimize Alzheimer’s disease risk for everyone.
- Factors Contributing to Alzheimer’s in Minority Populations
- Health Disparities and the Burden of Alzheimer’s
Some studies have reported a higher prevalence of Alzheimer’s disease among African-Americans and Hispanics compared to non-Hispanics whites. To better understand factors contributing to these observations, a team led by University of Pennsylvania, Philadelphia, researchers studied more than 1,300 people who had been diagnosed with either Alzheimer’s or deemed cognitively normal at their initial visit to the University of Pennsylvania Alzheimer Disease Center (Livney et al., 2011). Among these individuals, Hispanics (mostly Puerto Rican immigrants) had an earlier age of onset and greater severity of Alzheimer’s symptoms at their initial evaluation. They were also found to have lower average education levels and socioeconomic status than non-Hispanic whites. The Hispanics also suffered more depression than the African-Americans or non-Hispanic whites.
Interestingly, there was no association between the APOE ε4 risk-factor gene and cognitive status in the Hispanic group, in contrast to the strong association seen in the other two groups. African-Americans had a slightly older age at disease onset than non-Hispanics whites. However, both African-Americans and Hispanics had higher levels of cognitive impairment and dementia at their initial clinic visit than did non-Hispanics whites. Reduced access to clinical facilities did not appear to play a role in this disparity. Researchers surmise that the disparity could reflect differing perspectives of African-American and Hispanic family members regarding age-related cognitive decline, or that primary caregivers may lack the knowledge to detect symptoms earlier. These findings highlight some of the factors—from stress to educational levels—that should be considered in future research comparing immigrant and nonimmigrant groups.
A team led by University of Indiana, Indianapolis, researchers studied the incidence of cognitive impairment, no dementia (CIND) and mild cognitive impairment (MCI) in a group of older African-Americans (age 65-plus) in Indianapolis, IN (Unverzagt et al., 2011). “CIND/MCI” is a broad diagnostic category that includes all forms of age-related cognitive impairment, in which people have clinically evident symptoms but do not have dementia.
About 1 in 20 study participants developed CIND/MCI each year during the 5-year follow-up period. These rates are similar to those reported for other groups in the United States and abroad. Age was an important risk factor: among the oldest old (85-plus), 1 in 10 developed the condition every year. Those with a history of depression or head injury were also at greater risk of developing CIND/MCI. Education was a strong protective factor in that people with more years of schooling were at reduced risk.
Rush University, Chicago, researchers studied a very large sample of more than 9,500 older African-Americans and whites to see if educational levels affected health disparities (Barnes et al., 2011). They found that African-American participants with lower levels of education had poorer cognitive function and physical function (leg strength, balance, and walking speed) compared with similarly educated whites. More years of education were associated with better physical and cognitive health in both groups, and the positive effect of 12 years of education was similar for both groups.
Interestingly, additional years of education beyond high school had a significantly greater positive impact on physical and cognitive health in old age for African-Americans than for whites. Those with the highest levels of educational attainment enjoyed similar levels of cognitive health and physical function in old age. The study suggests that achieving greater levels of higher education in minorities might be helpful in reducing health disparities in old age.
Cognitive testing in minority ethnic groups can be complicated by demographic factors, including cultural background, language differences, and low educational levels. A team led by University of California, Davis, researchers compared the effectiveness of different tests in assessing cognitive decline in a sample of more than 600 Hispanics age 60 and older (Farias et al., 2011).
In this group, the subjects’ degree of everyday functional impairment, as measured by the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE), was a strong predictor of cognitive decline over the next 7 years. The IQCODE is an interview-based questionnaire completed by an “informant,” a family member or other person familiar with the study subject, and is available in Spanish.
The researchers found that baseline functional impairment reported by an informant may be a more sensitive indicator of future risk of cognitive decline than neuropsychological tests. Importantly, the informant-provided data are not strongly affected by educational level. In contrast to the results with the IQCODE, the subjects’ performance on a verbal memory test was not associated with future cognitive decline when demographic variables were taken into account. This study suggests that informant-based ratings of everyday function, which are easy to collect in clinical settings, are useful for identifying older Hispanic adults at risk of cognitive decline.
Almost two-thirds of Americans with Alzheimer’s disease are women. Scientists believe that the gender difference in Alzheimer’s prevalence results primarily from differences in lifespan. Because Alzheimer’s is an age-related disease and women typically live longer than men do, women may simply be more likely to survive long enough to develop the disorder.
However, past research comparing women and men who have already developed the disease suggests that women on average suffer from more severe symptoms than do men. In addition, a recent Mayo Clinic, Rochester, MN, study of a large Minnesota population found that men age 70 to 84 developed MCI, a possible precursor to Alzheimer’s, at substantially higher rates than women of the same ages (Roberts et al., 2012). The leaders of that study speculate that the Alzheimer’s disease process begins earlier in men than in it does in women, but that women decline more rapidly once the disease process has started.
Gender differences in other health factors may also contribute to the increased risk and/or severity of Alzheimer’s disease in women. For example, women have higher rates of depression and anxiety than men and on average get less exercise per week (Carter et al., 2012).
Alzheimer’s disease also impacts women disproportionately with regard to caregiving. Women do most of the caregiving for family members with the disorder (more than 70 percent of the unpaid caregivers for people with Alzheimer’s and other forms of dementia are women), and they suffer a greater burden of related stress and depression. At the same time, women who themselves suffer from Alzheimer’s receive less care and social support than do men with the disorder. Women with Alzheimer’s are much less likely to be living with a spouse and, regardless of their marital status, typically receive far fewer hours of care per week from family and friends than do men with the disease.
However, data suggest that husbands who are caregivers show greater physiological risk than do their peers who are not caregivers, with higher rates of obesity, triglycerides, blood pressure reactivity to acute stressors, and poorer immune function. In contrast, such differences are not as great between wives who are caregivers and wives who are not.
A growing body of research suggests that the burden of Alzheimer’s disease also varies among different ethnic and racial groups. In many U.S. communities, Alzheimer’s disease is significantly more prevalent among elderly African-Americans and Hispanics than among non-Hispanic whites of the same age. African-American and Hispanic individuals may also show more severe symptoms when they are first diagnosed. However, these ethnic and racial differences in Alzheimer’s disease prevalence are not consistent from community to community and may result from environmental factors, such as less education or income, poorer diets, or reduced access to health care.
In addition, current cognitive tests for diagnosing Alzheimer’s disease have been developed using largely white populations and may be less accurate when applied to other cultural groups. Efforts are underway to develop diagnostic tests that produce consistent results across different ethnic and racial groups. Biomarkers may prove particularly useful in this regard.