Patterns of Cognitive Change in Inductive Reasoning Ability in the Seattle Longitudinal Study: Covariates and Clinically Meaningful Outcomes

Open Access
- Author:
- Boron, Julie Blaskewicz
- Graduate Program:
- Human Development and Family Studies
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- May 19, 2005
- Committee Members:
- Sherry Lynn Willis, Committee Chair/Co-Chair
K Warner Schaie, Committee Member
Duane Francis Alwin, Committee Member
Bonnie J Meyer, Committee Member - Keywords:
- Inductive Reasoning
Cognitive Trajectories
Nagin Modeling
Cognitive ability
Cognitive Training
Older Adults - Abstract:
- The purpose of the current study was to examine variability in the rate of change in inductive reasoning ability in older adults. Although prior research has recognized the interindividual variability in rate of cognitive change, identification of distinct groups of cognitive trajectories and profiles for these trajectories are needed. This study investigated the distinct cognitive trajectories present in three samples with varying levels of participation in structured cognitive activity. The association of health behaviors, chronic diseases, cognitive reserve and cognitive style with distinct cognitive change trajectories was also examined. Finally, the long-term outcomes for health severity, mental status, everyday problem solving, and mortality were investigated as a function of trajectory group, training group and training gain. A sample of 422 individuals who participated in the Seattle Longitudinal Study for a minimum of 14 years and were at least 57 years of age at the baseline assessment were used in the current study. At baseline, participants had a mean age of 63.54 years and a mean education level of 14.42 years. The total sample was analyzed as three subsamples: nontrained (N=181), reasoning trained (N=118), and space trained (N=123). Nagin Mixture Modeling was employed to determine the optimal number and shape of the trajectories for the three subsamples, as well as the impact of the covariates. Analysis of covariance, Chi-square, and logistic regression analyses were utilized to investigate the clinically meaningful outcomes. Results indicated that there was significantly variability in reasoning ability over the 14-year period in each of the three samples. Those trained on inductive reasoning ability performed at comparable levels throughout the entire 14-year period, while those trained on spatial orientation ability demonstrated linear decline trajectories differing as a function of level. The nontrained sample showed the most variability in terms of trajectory shape. Thus, these findings suggest that structured cognitive activity is helpful for the maintenance of inductive reasoning ability in older adults exhibiting normative age-related decline. Investigation of the covariates revealed that cognitive style, particularly psychomotor speed and motor-cognitive flexibility, were consistently associated with trajectory group membership in each of the three samples. Individuals demonstrating higher levels of inductive reasoning ability throughout the 14-year period had higher levels of cognitive style at the final occasion of measurement compared to their lower functioning peers. In addition, cognitive reserve, specifically level of education and occupational status, were associated with trajectory group membership in the nontrained and reasoning trained samples. Individuals with higher levels of inductive reasoning ability had higher levels of educational and occupational attainment. These findings suggest that individuals with higher levels of inductive reasoning ability are able to adapt and respond to changes in the environment more readily, and have higher levels of cognitive reserve (as evidenced by educational and occupational levels). Finally, everyday problem solving was the outcome most consistently associated with trajectory group membership and training group. Individuals with higher levels of inductive reasoning ability, both through trajectory group membership, and training on inductive reasoning ability, demonstrated higher levels of everyday problem solving ability. This suggests that inductive reasoning is a particularly salient cognitive ability to consider in the study of everyday problem solving.