Adrenal circadian system in young and elderly human subjects: a comparative study

Area of Science:

• Endocrinology
• Chronobiology
• Gerontology

Background:

• Adrenocortical function and its circadian regulation are crucial for physiological homeostasis.
• Aging and neurodegenerative diseases like dementia can potentially alter hormonal rhythms.
• Understanding these changes is vital for managing age-related health conditions.

Purpose of the Study:

• To investigate circadian changes in plasma 18-hydroxy-11-deoxycorticosterone (18-OH-DOC), total, and unbound cortisol.
• To compare these circadian patterns across healthy young men, elderly men, elderly women, and elderly demented patients.
• To assess the impact of age, sex, and senile dementia on adrenocortical temporal organization.

Main Methods:

• Studied four groups: young men, elderly men, elderly women, and elderly demented patients.
• Collected blood samples every 4 hours to measure plasma 18-OH-DOC, total cortisol, and unbound cortisol.
• Collected hourly urine samples from young men to analyze urinary 18-OH-DOC, unconjugated cortisol, 17-hydroxycorticosteroids (17-OH-CS), and 17-ketosteroids.

Main Results:

• Circadian rhythms were identified for all studied steroids in all groups, with parallel secretory patterns.
• Elderly patients exhibited earlier acrophases for 18-OH-DOC compared to young men.
• No significant modifications in cortisol phasing were observed with age, sex, or dementia; amplitudes of 18-OH-DOC were lower in demented patients.

Conclusions:

• Aging and senile dementia do not induce major modifications in the temporal organization of adrenocortical function.
• The circadian rhythm of 18-OH-DOC shows some age-related phase shifts, with earlier acrophases in the elderly.
• Adrenocortical steroid secretion maintains its temporal organization even in advanced age and in the presence of dementia.