High cortisol levels are associated with cognitive impairment no-dementia (CIND) and dementia

Background: This study aimed to compare serum cortisol concentrations in cognitively healthy elderly and in subjects with cognitive impairment no dementia (CIND) and dementia, besides to evaluate these concentrations according to apolipoprotein E genotype (APOE).

Methods: Three-hundred and nine elderly enrolled in the Pietà Study (Brazil) were divided in 3 groups: control (n=158), CIND (n=92) and dementia (n=59) and had concentrations of morning serum cortisol measured. Hormone concentrations were measured by chemiluminescence and APOE genotypes were determined by PCR followed by restriction fragment length polymorphism (RFLP).

Results: Medians of cortisol concentrations (μg/dl) for the groups were 12.14 (interquartile range - IQR 6.34) for control, 13.65 (IQR 5.88) for CIND and 14.47 (IQR 7.35) for dementia. Significant differences were observed for control vs. CIND (P=0.003), control vs. dementia (P=0.001), but not for CIND vs. dementia (P=0.269). No association was observed between cortisol concentrations and APOE genotype among the groups (P=0.348).

Conclusions: The elevation in cortisol concentrations is associated with dementia, independently of APOE genotypes. Further studies are required to understand if elevation of cortisol is an initial event and how hippocampal damage and the loss of hypothalamus-pituitary-adrenal (HPA) axis inhibition may affect its concentrations.