Cognitive ability across the life course and cortisol levels in older age

Elevated cortisol levels have been hypothesised to contribute to cognitive ageing, but study findings are inconsistent. In the present study, we examined the association between salivary cortisol in older age and cognitive ability across the life course. We used data from 370 members of the 36-Day Sample of the Scottish Mental Survey 1947, who underwent cognitive testing at age 11, and were then followed up at around age 78, completing further cognitive tests and providing diurnal salivary cortisol samples. We hypothesised that higher cortisol levels would be associated with lower cognitive ability in older age and greater cognitive decline from childhood to older age, but also lower childhood cognitive ability. Few of the tested associations were significant, and of those that were, most suggested a positive relationship between cortisol and cognitive ability. Only one cognitive measure showed any sign of cortisol-related impairment. However, after correcting for multiple comparisons, no results remained significant. These findings suggest that cortisol may not play an important role in cognitive ageing across the life course.