The proposed research bridges strength of epidemiology and survey research with those of structural neuro-imaging all cognitive assessment, which are more typically conducted without close attention to the population from which normal volunteer subjects are recruited. The proposed study sample will consist of 242 adults ages 20+, selected with probability sampling so that there will be 11 men and 11 women in each of 11 age strata, with 110 of the subjects aged 65 years or older, and subfields aged 80 years and older. Selection probabilities will ensure that the samples racial distribution corresponds to the proportional representation of African-Americans and Caucasians in the U.S. adult Population, based on the U.S. census projection for 1995, and that approximately 50% of subjects with each age stratum will be high school graduates. This cross-sectional survey will investigate suspected age-related differences in neuroanatomy, cognitive functioning and performance (e.g., activities of daily living). After sampling, subjects will be recruited for office-based measurements of quantitative volumetric neuro-anatomy, using reliable measures obtained from 3-D volume-rendered MRl scans. At the same time, detailed measures of cognitive functioning, current physical health, health history and plasma lipids will all be assessed.
The specific aims of the proposed study are: To assess cross- sectional age differences in generalized and regional brain measures from MRI, multiple domains of cognitive performance, and functional limitations or disability. This will yield data on specific differences across age strata as well as a set of comprehensive reference values for brain anatomy, cognition, and function across, age strata. We envisage this cross-sectional survey work serving as the basis for future prospective longitudinal studies of age-related brain anatomic changes related to impaired functioning. We will assess specific correlative inter-relationships among MRI and the sets of functional measures, investigating variation in these correlations across age strata. For example, parameters of brain structure and functional status will be examined in terms of their association with suspected sources of variation from medical history, demographic background, and current medical status. Images, reference values and other products of this research gathered in the proPosed project will be made available on-line via internet for use in other research centers; in the case of MRI images, as part of NIH's BRAIN MAP project.
