| BACKGROUND: There is a large literature examining the protective effects of physical, social, and educational engagement during the cognitive aging process. The literature has not examined the association between cognitive intra-individual variability (IIV) and these lifestyle factors. METHODS: The purpose of this study is threefold: (1) to use bivariate correlations and tests of dependent correlations to explore broad and domain-specific cognitive IIV and functional outcomes and (2) to prospectively examine, using a series of multivariate regressions, how changes in cognitive IIV impacts engagement in lifestyle activities and vice versa and (3) examine the above two aims using a novel measure of cognitive IIV. RESULTS: Broad cognitive IIV was superior to domain-specific IIV across all outcomes. A geometric measure of variability was superior to existing IIV approaches. Change in cognitive IIV over three years was linked to decreased social engagement at Time Two, but results were mixed across measures of cognitive IIV. CONCLUSIONS: Broad cognitive IIV may be a superior method of assessing cognitive IIV due to the ability to detect greater pathological variability. These results add to the literature on the impact of cognitive functioning and lifestyle disengagement, using a new methodological approach (cognitive IIV). |
