Salivary cortisol and memory function in human aging

Objective: To examine the association of salivary cortisol with cognitive changes in a 3 year longitudinal study. Previous studies have suggested that elevated glucocorticoid concentrations alter hippocampal neuronal morphology, inhibit neurogenesis, and impair cognition. Methods: Salivary cortisol samples were collected at home by 79 cognitively intact older persons (mean age 78 +/- 7 years) at 08:00, 15:00 and 23:00 h, and collections were repeated annually for 3 years. Cognitive function was also assessed annually. Results: The mean cortisol level of samples taken at three times of day and the cortisol concentration at 23:00 h were significantly associated with poorer performance on tasks of declarative memory and executive function. Of 46 subjects who completed the entire 3 year study, higher initial cortisol concentration at 23:00 h predicted a decline in performance of delayed paragraph recall. Conclusion: These results partially confirm previous findings that high cortisol is associated with impaired declarative memory function in non-demented older persons. In addition, our data show that high salivary cortisol concentrations predict a decline in memory function over the next 3 years. (c) 2005 Elsevier Inc. All rights reserved.