How it works

The Main Communication Pathways:

1. The HPA Axis (Stress Circuit):

• Hypothalamus → Pituitary gland → Adrenal glands

• Releases cortisol, the main stress hormone

• Prolonged cortisol weakens immune function (e.g., suppresses white blood cells, increases inflammation)

2. The Autonomic Nervous System:

• Sympathetic (fight-or-flight): increases stress response, slows digestion, lowers immune defenses

• Parasympathetic (rest-and-digest): promotes healing, digestion, and immune activity

3. Cytokines & Neurotransmitters:

• Cytokines are immune signaling proteins that can enter the brain and change mood.

• Pro-inflammatory cytokines are linked to depression and fatigue.

4. Gut-Brain-Immune Axis:

• 70% of immune cells are located in the gut.

• Gut microbiota influence mood and immunity through the vagus nerve and neurotransmitters like serotonin.

Example:

• During exam season, students often experience more colds or cold sores. Stress triggers cortisol, which dampens immune defense and makes viruses reactivate.

Quote:

“The immune system thinks the brain is part of the body. The brain has finally agreed.” – Robert Ader