67 Cognitive Reserve, Depressive Symptoms, and Functional Ability in Older Adults

Abstract

Objective:Cognitive reserve has been linked to functional ability, and depression has been shown to be associated with more functional impairment in older adults. While cognitive reserve and depression are associated and have each been shown to impact functional impairment, the independent impact of cognitive reserve on functional ability after accounting for depressive symptoms has not been explored. For the purpose of this study, years of education served as a proxy for cognitive reserve, which is consistent with the literature. It was predicted that higher levels of education would be associated with better functional ability regardless of age and severity of depressive symptoms.Participants and Methods:Participants (ages 55 to 90) were drawn from the Alzheimer’s Disease Neuroimaging Initiative (N=3407); participants with major depression were not included. Subsyndromal depressive symptoms were measured using the Geriatric Depression Scale (GDS < 6) and functional impairment was assessed using the Functional Activities questionnaire. A three-stage hierarchical regression was conducted with functional ability as the dependent variable.Results:Age, entered at stage one of the regression model, was a significant predictor (F(1,1427) =49.75, p<.001) and accounted for 3.4% of the variance in functional ability. Adding depressive symptoms to the regression model led to a significant increase in variance explained (F(1,1426) = 64.57, p<.001), accounting for an additional 4.2% of the variance in functional ability. Adding years of education to the regression model explained an additional 1.4% of variance in functional ability and this increase in variance explained was significant (F(1,1425) = 22.53, p<.001).Conclusions:Cognitive reserve (operationalized as higher levels of education) was associated with higher functional ability even after accounting for age and depressive symptoms.