Alterations in diurnal cortisol secretion, cognitive performance and frailty in an aging population: Preliminary results of the KORA Age 1 Study

Abstract

Dysregulated cortisol secretion is hypothesized to be etiological in the development of heart disease, osteoporosis, cognitive decline and frailty in the elderly. However, the variance of cortisol regulation has not been assessed within this context. We sought to examine associations between variances of diurnal salivary cortisol measurements and cognitive performance/frailty in healthy elderly people. A cross-sectional analysis was conducted using data obtained from the KORA Age population-based study. Salivary cortisol samples were collected from participants using Salivette® collection devices at awakening, 30 min after awakening, and late evening. Cognitive performance was assessed by the Telephone Instrument for Cognitive Status (TICS) adjusted for education per Lacruz et al. (2012), and frailty was defined according to Fried et al. (2001). Among 744 (377 male and 367 female) study participants, 4.4% ( N = 33) suffered from probable dementia, and 15.3% ( N = 114) had mild cognitive impairment. Significant differences were observed between cognitive status and cortisol measures in the morning ( p -value 0.021), 30 min after awakening ( p -value 0.002), and in the ratio of morning versus late evening cortisol levels ( p -value 0.019). A small portion of participants were classified as frail (3.36%, N = 25), yet over a third (35.2%, N = 262) were pre-frail. Cortisol measures of 30 min after awakening ( p -value 0.019), late evening ( p -value 0.003) and the ratio of morning versus late evening cortisol levels ( p -value 0.0002) showed significant associations with these distributions. No significant associations were observed with the commonly used cortisol awakening response. Associations between salivary cortisol and cognitive performance or frailty were strongest when considering the ratio between morning and evening levels of cortisol. Future investigations will apply analytical models to further understand cortisol homeostasis particularly in the context of cognition and frailty in people with advanced age.