Predictors of hair cortisol concentrations in older adults.

People at older ages are at increased risk for developing stress-related diseases associated with chronically elevated cortisol secretion. However, the main factors contributing to such endocrine alterations in this age group are still largely unknown. This cross-sectional study examined patterns of long-term integrated cortisol secretion, as assessed in hair, in a sample of 654 participants in middle and old adulthood (mean age: 65.8 years; range: 47-82 years) from the German cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC) study in Potsdam. Hair cortisol concentrations (HCC) were determined from the first scalp-near 3 cm hair segment and several sociodemographic, lifestyle, anthropometric, disease-related, and psychological parameters were assessed. In simple linear regressions, HCC were found to increase with participants' age and to be higher in men compared to women. HCC also showed positive associations with waist-to-hip ratio, waist circumference, smoking, prevalent type 2 diabetes mellitus, mental health, daytime sleeping, and being unemployed or retired--as well as a negative association with diastolic blood pressure. After full mutual adjustment, only age and smoking remained independent predictors of HCC. The association between prevalent type 2 diabetes mellitus and HCC was attenuated but still persisted independently in women. Similar, a positive relationship between HCC and alcohol consumption was found in women. The current results confirm previous evidence of positive associations of HCC with age, sex, alcohol consumption, and type 2 diabetes mellitus and add new knowledge on factors--such as smoking--that may contribute to elevated cortisol levels in people at older ages.