It is clear that with the rapid growth of the aging African American population and the suspected increased number of older African Americans who will experience cognitive decline, efforts will need to be extended to increase participation in studies that include brain donation. Similar to the considerable effort that is required to have high numbers of minorities participating in longitudinal cohort studies that emphasize high follow-up participation, the effort to obtain minority autopsies will need to be substantial as well. Although the flowchart likely underestimates the number of people we reach through our outreach efforts (because approximately 25% of attendees do not fill out an interest form or provide enough information to locate them after the presentation), it is clear that the entire process from recruitment to autopsy requires considerable staff time and effort. The results to date demonstrate that having a visible positive presence in the minority community and strengthening community partnerships are effective strategies for relieving the barriers to participation in brain donation studies.
Having pathologic data on relatively large numbers of well-characterized African Americans with comprehensive cognitive testing will not only contribute to our understanding of the neurobiologic basis of cognitive impairment, but will facilitate our ability to understand the impact of race and racial differences on neuropathology and on the relationship between neuropathology and cognition. It is important to note that there has been considerable debate in epidemiological research on the conceptualization of race in studies of racial differences [36
] with some proposing that race is a biologic concept that should serve as a proxy for genetic variation and others proposing that race is solely a social concept driven by social and economic forces [e.g., 37
]. Studies of racial differences in neuropathology and cognition will be particularly susceptible to a biologic conceptualization of race. However, there are no known biologic criteria on a phenotypic level to determine ones race [39
], and at the level of the genotype, there is greater within-group heterogeneity than between-group heterogenity [e.g., 41
]. Although there is evidence that some genetic factors may vary along racial/ethnic categorizations (e.g., sickle cell anemia, lupus, Tay-Sachs), most racial differences stem from multiple cultural and social attributes often associated with race including, but not limited to, socioeconomic status, low literacy and education, racial discrimination, residential segregation, and lack of access to quality healthcare [e.g., 43
]. Rather than attempting to define race in strict biological or social terms, our goal is to develop a better understanding of the ways in which racial differences lead to disease biology and its functional consequences [45
]. To the extent that health disparities arise from insults to a complex system that is represented by the interaction between genes and environments, identifying the conditions under which environmental triggers modify genetic risk or vice versa will place us in a better position to compare different population groups and understand disparities in health when we find them [47
This study has an important limitation. The study uses a volunteer cohort of people drawn from the community that may not be representative of older community-dwelling African Americans. However, participants in MARS have a wide range of education and lifestyle experiences, and published data suggests that they are comparable to other cohorts of older African Americans in terms of cognitive test performance [48
]. Moreover, our goal of determining the neuropathologic basis of cognitive impairment in older African Americans necessitates labor-intensive, in-depth characterization of clinical features proximate to death, and high rates of follow-up participation and autopsy, which would be difficult to achieve in a population-based setting. We are not aware of any large longitudinal cohort studies of African Americans that include organ donation on sufficient numbers of persons for meaningful analyses on the relation of neuropathology to cognition, or on the risk factors to neuropathology. Our recruitment results to date are consistent with other investigators who do research with underserved populations [51
], and show that making authentic connections with potential participants and providing needed services to those who may not have access to up-to-date health information, helps to solidify relationships and creates a sense of “giving first” before asking for anything from the community. This reciprocity is not only important for establishing a culture of trust, but builds an infrastructure that allows the research to continue beyond individual projects.
The novel strategies, resources and infrastructure that have been put in place for the cohort studies at Rush will be fully utilized to insure that we continue to successfully educate, enroll, and obtain autopsy on more than 100 African Americans. The clinical and neuropathologic data generated from the Minority Aging Research Study, together with the other aging cohort studies at the Rush Alzheimer’s Disease Center is likely to greatly expand our understanding of the neuropathologic basis of cognitive impairment in older African Americans.