Is the emergence of functional ability decline in early old age related to change in speed of cognitive processing and also to change in personality?

To test whether the onset of functional ability decline in early old age is related to change in speed of cognitive processing and personality characteristics. Among 500 randomly sampled participants, the 230 cases that did not show impairment in functional ability were selected. Mean age at Time I was 62.4 years. For this subsample, the emergence of functional ability decline was tracked across a 12-year observation period. The emergence of functional ability decline was related to change in speed of cognitive processing. Decline in functional ability was also related to increased neuroticism and external control, whereas this was not the case regarding extraversión and internal control. Cognitive processing speed was shown to be a predictor of functional disability decline; in addition, the results provided initial evidence that functional ability decline in the early aging phase could be accompanied by changes in personality, particularly neuroticism and external control. (author's abstract