Is depression really a disease?

Someone is diagnosed with major depressive disease if they check off 5 or more of the following, but those 5 or more have to include #1 and #2:

1. Depressive mood

2. Decreased interest in pleasure

3. An increase or decrease in appetite or weight 

4. Increased or decreased sleep

5. Fatigue

6. Feeling of worthlessness/inappropriate guilt

7. Decreased ability to concentrate

8. Agitation or retardation 

9. Recurrent thoughts of death or suicide

Why are we not looking at other factors that may be more objective, such as: 

• Poor diet

• Low vitamin D

• Low testosterone

• Hypothyroidism 

• Low vitamin B1

• Not getting enough sleep 

• Fatigue from Lyme disease, EBV, other viruses, or anemia

• Chronic pain and inflammation