# 7. Deficiency

Thiamine deficiency is often overlooked in modern medicine, yet it persists in alcoholism, malabsorption syndromes, chronic illness, and high-carbohydrate diets.

### **Progression:**

* **Early signs:** Fatigue, irritability, poor concentration, mild neuropathy.
* **Moderate deficiency:** Muscle weakness, anorexia, gastrointestinal discomfort, mood changes.
* **Severe deficiency syndromes:**
  * **Dry beriberi:** Peripheral neuropathy, muscle wasting, foot drop.
  * **Wet beriberi:** Cardiac enlargement, tachycardia, heart failure with edema.
  * **Wernicke’s encephalopathy:** Confusion, ataxia, ophthalmoplegia; can progress to coma.
  * **Korsakoff’s psychosis:** Chronic amnesia and confabulation due to permanent brain damage.

**Mechanistic basis:** Energy failure in neurons and cardiomyocytes, lactic acidosis, and increased oxidative stress are central to thiamine deficiency pathology.