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.
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.
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.