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.