An examination of the relationships among affect, diurnal cortisol slope, and memory in elderly with cognitive impairments

Abstract

Introduction: Memory deficit is a common symptom of cognitive decline in older adults. It has been linked with emotional factors and flattened diurnal cortisol slopes. The present study aimed to evaluate the mediating role of diurnal cortisol pattern in the relationship between negative affect and memory and functional outcome in elderly with cognitive impairments. Research Design: The study comprised 190 Chinese older adults who were recruited from local elderly daycare centers and residential homes in Hong Kong. The participants completed self-report measures on affect and functional outcome, two neuropsychological assessments on episodic, short-term, and working memory, and five salivary cortisol measures. Structural equation modeling was used to examine the direct and indirect effects of negative affect on functional outcome via diurnal cortisol pattern and memory. Results: The cascading structural equation model provided an adequate fit to the observed data. The direct effects specified in the combined model were not significant. There was a significant and negative indirect effect from negative affect to functional outcome via diurnal cortisol slope (but not mean cortisol) and memory. Conclusions: The current findings support a mediating role for cortisol such that elderly with greater negative affect showed flattened diurnal cortisol slopes which in turn led to poorer memory and functional outcome. Future longitudinal studies should elucidate the temporal ordering and causality of the relationship between the changes in stress and memory.