Background. Depression is a prevalent and disabling condition associated with functional impairment in the elderly. This study aimed to investigate the role of cognitive mediators in the relationship of depressive symptoms and functional performance in a large cohort of community-dwelling older adults.
Methods. Latent growth curve model was applied to explore relationships between depression and functioning, including models relating depression influence on functional performance directly and indirectly through the cognitive abilities, and relating functional performance influence on depression directly and indirectly through the cognitive abilities. Baseline depressive symptoms and baseline functional performance were replaced by growth trajectories for model test. The data for this study were obtained from the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) randomized, controlled trial. Data of the no-contact control group from baseline through the third year were included for analysis. Memory, reasoning, or processing speed ability were treated as mediators between depressive symptoms and functional performance. The selected model was then applied to depressed and non-depressed elderly, respectively. The selected model was also applied to participants clustered within the six different sites of the study.
Results. Baseline depressive symptoms had no direct effect on functional slope as determined by the latent growth curve model relating depression scores to performance measures of function through measures of memory, reasoning, and speed of processing and moderation of covariates. Baseline depressive symptoms inversely influenced functional intercept directly or through cognitive pathways. The effect of processing speed intercept on functional intercept was mediated by memory intercept and reasoning intercept. Memory slope and processing speed slope were not significant mediators between depressive symptoms and functional intercept or functional slope. For participants in the depressed group, the significances of the association between depressive symptoms and cognitive abilities and functional performances is attenuated, while for non-depressed elderly, the association between depressive symptoms and functional intercept remains significant.
Conclusions. The results of this study can be used to predict functional status over time. They can serve as the basis of intervention or prevention of functional impairment due to depressive symptoms among the elderly.
|Advisor:||Rebok, George W.|
|School:||The Johns Hopkins University|
|School Location:||United States -- Maryland|
|Source:||DAI-B 68/04, Dissertation Abstracts International|
|Subjects:||Ocean engineering, Public health|
|Keywords:||Cognitive mediators, Community-dwelling, Depression, Older adults|
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