Individual differences in rates of change in cognitive abilities of older persons.

The authors examined change in cognitive abilities in older Catholic clergy members. For up to 6 years, participants underwent annual clinical evaluations, which included a battery of tests from which summary measures of 7 abilities were derived. On average, decline occurred in each ability and was more rapid in older persons than in younger persons. However, wide individual differences were evident at all ages. Rate of change in a given domain was not strongly related to baseline level of function in that domain but was moderately associated with rates of change in other cognitive domains. The results suggest that change in cognitive function in old age primarily reflects person-specific factors rather than an inevitable developmental process.