Original Article

Medical Comorbidity in Black and White Patients with Alzheimer’s Disease

Authors: Edward Zamrini, MD, Jo Ann Parrish, LPN, Dee Parsons, Lindy E. Harrell, MD, PHD

Abstract

Background: Little is known about co-medical illnesses in black and white patients with probable Alzheimer’s disease (AD).


Methods: To address this question, we used two methods. In the first (Group I), black and white probable AD patients were matched on age at presentation to the clinic, age of onset of AD, duration of illness, and Mini-Mental State Examination scores; then, a variety of co-medical illnesses were compared between blacks and whites. In Group II, whites were randomly matched to blacks on the variables listed above.


Results: In Group I, blacks were found to have a higher rate of hypertension than whites, whereas whites had a higher incidence of atrial fibrillation and cancer than blacks. In Group II, age at presentation to the clinic was found to be shorter for men than for women; duration of illness was shorter for black men than for white men, white women, and black women; and Mini-Mental State Examination scores were lower in blacks than whites. As in Group I, blacks were found to have a higher rate of hypertension, whereas whites had higher rates of atrial fibrillation, cancer, coronary artery disease, high cholesterol, and gastrointestinal disease.


Conclusion: In both groups, black patients with probable AD had a higher rate of hypertension than white patients with probable AD, and whites had higher rates of atrial fibrillation and cancer. This finding suggests that these comorbid illnesses in black and white patients with probable AD is not due to a statistical Type II error, but rather to differences in these groups.


Little is known about differential clinical characteristics of Alzheimer’s disease (AD) among and between ethnic populations in the United States. Even less is known about the differences between comorbid diseases associated with AD across ethnic groups. Recent studies, however, do suggest some differences in clinical characteristics and comorbid diseases between whites and blacks with AD. For example, Hargrave et al 1 found that black AD patients, compared with white AD patients, have a shorter duration of illness, lower Mini-Mental State Examination (MMSE) scores, higher Blessed Roth Dementia Rating Scale scores, and higher rates of hypertension at the time of initial diagnosis. Likewise, Shadlen et al 2 also found lower MMSE scores and higher rates of hypertension, without differences in ischemic heart disease or stroke, in black AD patients when compared with white AD patients.


In this study, we sought to determine whether there were differences in comorbid medical diseases in black and white probable AD patients. To test this hypothesis, two methods of matching blacks and whites were used. In the first (Group I), black and white probable AD patients were nonrandomly matched on age at initial presentation to the clinic, age at onset of illness, duration of illness, and MMSE scores. In the second method, blacks and whites with probable AD were randomly matched on the variables listed above (Group II). After these procedures, the frequency of comorbid diseases was determined.

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