The Role of Ethnicity in Alzheimer's Disease: Findings From The C-PATH Online Data Repository

Background: Ethnic minorities seem to be at an increased risk of Alzheimer's disease (AD). However, little is known about ethnic differences and the risks of early onset AD (EOAD). Objective: Cognitive function changes over time and odds of EOAD by ethnicity were analyzed by the mixed model and the logistic regression. Methods: Information on demographics, self-reported co-morbidities, cognitive functions (MMSE and ADAS-COG), and ApoE genotypes were collected for 6,500 subjects with AD obtained from the placebo arm of clinical trials; this data was examined by ethnicities: Caucasian, Asian, African American, Hispanic, and other minorities-including Native Alaskans, Americans, and Hawaiians. Results: Of the total subjects, Caucasians accounted for 89.0%, followed by 4.7% Asians, 2.7% African Americans, 2.4% Hispanics, and 1.2% Native Americans, Alaskans, and Hawaiians. Age, gender, EOAD status, co-morbidities, family history of AD, and ApoE genotypes were significantly different by ethnicity. ApoE epsilon 2 allele is possibly overrepresented in the Native Americans, Africans, Hawaiians, and African Americans. A significant interaction with time, ethnicity, and cognitive performance was found, indicating more cognitive deterioration in other minorities than Caucasians for mini-mental state (p < 0.01). After adjusting for co-morbidities and gender, the odds of EOAD among African Americans (OR: 1.6, 95% CI: 1.1-2.4) and Native Alaskans, Americans, and Hispanics (OR: 2.1, 95% CI: 1.2-3.5) were significantly higher, compared with Caucasians. Conclusions: Ethnicity may impact AD through age of onset, co-morbidities, family history, ApoE gene status, and cognitive change over time. The greater odds of EOAD among African Americans, Alaskans, and Hawaiians suggest that some ethnicities may be at risk of AD at a younger age.