Cognitive and affective disorders in the elderly: a neuroendocrine study

Abstract

Both in physiological and pathological brain aging, cognitive and affective disorders usually keep up with significant morphological and metabolic changes of brain areas possibly involved in the control of mood, learning and memory, as well as in the modulation of the hypothalamo-pituitary-adrenal (HPA) axis. The aim of this work was to study the circadian rhythm of serum cortisol and dehydroepiandrosterone (DHEAS) in 25 old demented patients and 10 old unipolar depressed patients, compared with 21 old and 13 young controls. The circadian profile of serum cortisol was clearly flattened in elderly subjects,both healthy and demented, in comparison to young controls, with significantly higher cortisol levels at nighttime. The occurrence of minor depression was associated with a further increase of the cortisol mean levels in old demented subjects, but not in the healthy ones. The trend towards the increase of the nocturnal cortisol levels was also evident in old subjects with major depression. The decline of DHEAS secretory pattern was clearly age related,being additive factors to both dementia and major depression. No significant influence of minor depression on DHEAS secretion was found. The cortisol/DHEAS molar ratio,considered as a good index of the brain steroidal milieu, progressively increased with aging and exhibited a further increase related to the occurrence of senile dementia or minor depressive symptoms. The value of the same ratio was higher in elderly subjects with major depression, than in age-matched healthy controls. In conclusion, the occurrence of major depression or even only of depressive symptoms seems to amplify the changes of the adrenal steroidal secretory pattern, already present in physiological aging.