The study has several strengths. Individuals known to be free of dementia or free of MCI at baseline are followed for the development of incident disease and cognitive decline. There is a large sample size and a relatively long duration of follow-up with repeated measures of cognition and large number of persons with incident disease. The follow-up rate of survivors and the autopsy rates are very high, which reduces the biases that occur when persons drop out of longitudinal studies or when autopsy is not obtained. Structured procedures ensure uniformity of diagnostic decisions across time and space. Examiners are blinded to previously collected data, which further reduces bias. The study enrolls participants with a wide range of experiential factors in order to facilitate investigating the role of these factors in the development of neural reserve. Finally, a unique aspect of the study is that both clinical and pathologic data collection procedures are similar in many respects to the Religious Orders Study, which allows data to be merged for analyses that may have small to moderate effects [32,33,123,154,159,165,166].
