In an ongoing prospective community study, a random sample of rural
elderly persons was screened with cognitive tests (including the CERAD
neuropsychological battery) at study entry and an average of 2 years
later. We examined 1,017 subjects, nondemented at study entry, at both
waves, with the Mini-Mental State Exam, Story Recall, Word List Recall
and Recognition, Boston Naming Test, Verbal Fluency, Praxis, Clock
Drawing, and Trailmaking. Overall, the cognitive performance was stable,
with either no mean change or a small mean decline over 2 years;
however, standard deviations were relatively large, implying individual
variation of questionable clinical significance. These data provide a
set of population-based longitudinal cognitive norms and have
implications for dementia screening.