CONCEPT
Cortisol
The primary glucocorticoid hormone of the stress response — the molecule that sharpens attention and mobilizes glucose in acute mobilization, and the molecule that suppresses immunity and erodes the hippocampus when chronically elevated.
Cortisol is the central effector molecule of the HPA axis and the single most studied hormone of the stress response. In acute elevation, cortisol mobilizes glucose from liver glycogen stores, sharpens cognitive attention, suppresses non-essential functions (digestion, reproduction, immune deployment), and prepares the body to meet immediate demand. In chronic elevation — the hormonal signature of the resistance phase — cortisol sustains heightened function while producing cumulative damage: immune suppression that increases infection risk, cardiovascular remodeling that increases heart disease risk, hippocampal atrophy that impairs memory consolidation, and metabolic dysregulation that produces insulin resistance. The distinction between acute and chronic cortisol elevation is the distinction between a hormone that protects and a hormone that damages, and the same molecule serves both functions depending on duration.
In The You On AI Field Guide
Cortisol was isolated in the 1930s by Edward Kendall and Philip Hench, who received the Nobel Prize in 1950 for their work on adrenal steroids. The hormone's role in stress response