A growing body of literature suggests that the incidence and the prevalence of Alzheimer's disease in the United States are higher among African Americans and Hispanics than among non-Hispanic whites (Demirovic et al., 2003; Gurland et al, 1999; Tang et al., 2001). In a longitudinal study of 1,788 African American, Caribbean-Hispanic, and Caucasian Medicare beneficiaries, the Alzheimer's rates in African Americans and Hispanics appeared to be twice as high as those seen in non-Hispanic whites (Tang et al., 2001). Increased prevalence rates may be explained in part by age, education, or apolipoprotein E (APOE) genotype, which predisposes an individual to Alzheimer's, and coexisting medical conditions (Evans et al., 2000; Shadlen et al., 2006; Stern et al., 1994; Tang et al., 1998, 2001).
In addition to the increased prevalence of Alzheimer's in minority populations, results of some studies suggest that disease onset may occur earlier in African American and Hispanic patients with Alz- heimer's compared with their non-Hispanic white counter- parts (Clark et al., 2005a; Shadlen et al., 1999). Earlier onset may be related to the higher rates of risk factors associated with the disease, including hypertension, diabetes mellitus, or other meta- bolic abnor- malities, compared with non-His- panic whites (Baldwin et al., 2007; Campbell et al., 2005; Shadlen et al., 1999; Tang et al., 2001).
Compounding the prob- lems of increased disease risk and possible earlier onset, African American and Hispan- ic patients are often diagnosed at later stages of the disease, with many of them experienc- ing a delay of up to seven years before their symptoms are evaluated (Clark et al., 2005b; Fitten, Ortiz, and Ponton, 2001; Griffith et al., 2006; Tang et al., 2001). Furthermore, a gap in treatment has been identified among minority patients with the disease. An analysis of 2,573 patients with Alzheim- er's, who were seen between 1999 and 2003 at Alzheimer's Disease Research Centers of California, found that past or current use of a widely accept- ed treatment, Cholinesterase inhibitors (ChEIs), was 40 percent lower among minority patients compared with white patients (Mehta et al., 2005).
This article describes the potential consequences of delays in diagnosis and treatment of Alzheimer's disease in African American and Hispanic populations, identifies barriers to the timely diagnosis and treatment of the condition in these populations, and also explores issues relating to the underrepresentation of minorities in clinical trials. Two recent studies that do focus on African American and Hispanic patients in an examination of the efficacy and safety of the ChEI donepezil are reviewed.
Consequences of Delay in Diagnosis and Treatment
Delay in the diagnosis and treatment of Alzheimer's may have important consequences. Delayed diagnosis may result in the patient having reached a greater severity of dementia by the time a diagnosis is made, which translates to greater cognitive impairment at the time of diagnosis. Accordingly, significantly greater cognitive impairment has been observed upon diagnosis in African American versus white Alzheimer's patients, although the duration of illness was not reported as being longer (Hargrave et al., 1998; Shadlen et al., 1999). When patients are diagnosed at a later stage of disease, they may be less able to contribute to decisions regarding disease management. In addition, delayed diagnosis may limit the capacity of the patient and family to plan for the future (e.g., financially, making housing decisions) and the time available to arrange for full utilization of community resources.
Delaying the diagnosis of Alzheimer's and the initiation of pharmacotherapy may also limit the potential benefits of treatment. In patients with the disease, pharmacotherapy with ChEIs may help to improve or stabilize cognition, preserve functional ability, and potentially reduce or delay the need for nursing home placement (Beusterien et al. …