Cortisol secretion and Alzheimer's disease progression

Background: Mild hypercortisolemia is a frequent concomitant of Alzheimer's disease (AD). In an effort to ascertain the relationship between serum cortisol concentration (CORT) and disease progression, aging, and survival, we followed 9 persons with AD, ages from 56 to 84 years, from an original cohort of 19 enrollees with serial cognitive testing and CORT determinations. Methods: The cognitive instrument was a modification of the Alzheimer's Disease Assessment Scale-Cognitive (mADAS-COG). Serum cortisol determinations were performed at noon, and an Afternoon Cortisol Test (ACT) was used to obtain an estimate of average CORT. Results: Baseline 12:00 hours CORT but not ACT correlated significantly with the change in mADAS-COG (r = .90, p < .01). ACT levels increased as the mADAS-COG increased over time (p = .037), by 0.156 ± 0.06 μg/dL for each one-point increase (indicating greater impairment) in cognitive test score. ACT levels did not increase significantly simply with aging. For the entire cohort of 19 subjects, neither baseline ACT nor 12:00 hours CORT was significantly related to survival. Conclusions: Hypercortisolemia in AD appears related to the clinical progression of the disease, but not to aging or length of survival.