Twenty-four-hour urinary cortisol levels in Alzheimer disease and in dysthymia

During senescence, homeostatic and stress-response capacities are impaired particularly in patients with dementia and depression. Therefore, the study of the hypotalamic-pituitary-adrenal (HPA) axis function, involved in the physiological adaptation processes to environmental stimuli, appears to be relevant. In this study, we evaluated the 24-hour urinary free cortisol in a group of 20 normal young adults (C) (12 males and 8 females, mean age 46 ± 4 years); in a normal elderly group of 23 subjects (15 males and 8 females, mean age 68 ± 9 years); in a group of 15 patients with Alzheimer disease (AD) (8 males and 7 females, mean age 70 ± 8 years) and in a group of 22 dysthyrnic elderly patients (8 males and 14 females, mean age 69 ± 4 years), to evaluate the mutual influence between these states and the HPA axis function. Subjects with depression different from dysthymia, under drug treatment or with acute illness or in chronic conditions, which could influence HPA axis function, were not included. The diagnoses of AD and dysthymia were established according to the DSM-IV criteria. We evaluated the 24-hour urinary cortisol using commercial RIA Kits (Radim, Pomezia, Italy) in all subjects. Statistical analysis was performed by means of the Student's t-test, in the normal elderly urinary cortisol values are 34.18 ± 13.85 μg/day, higher, but not significantly, than those of C, whose urinary cortisol is 27.78 ± 10.36 μg/day. In AD the urinary cortisol is 53.18 ± 17.49 μg/day and in dysthymic patients is 55.31 ± 26.93 7mu;g/day. Hyperactivity of HPA axis in AD (p<0.001) and in dysthymic patients (p<0.01) both compared to normal elderly and to C is evident. Our data confirm those of the literature and emphasize a low increase in 24-hour urinary cortisol in normal elderly compared to young adults and an involvement of the HPA axis in AD, with values of the 24-hour urinary cortisol significantly higher than those of C. Moreover, our data show a HPA axis hyperactivity in dysthymic patients, as reported in the literature for major depression. This hyperactivity of the HPA axis function, according to the "glucocorticoid cascade hypothesis", indicates that dysthymia might be considered as a very important risk factor for AD.