According to the CDC (Centers for Disease Control and Prevention), depression affects 1 of 10 adults in the U.S. While many factors, such as abuse, medications, conflict, or death or loss, increase the chances of depression, Maes and colleagues writing in Neuroendocrinology Newsletters, propose depression to be an inflammatory and degenerative disorder:
There is now evidence that depression, as characterized by melancholic symptoms, anxiety, and fatigue and somatic (F&S) symptoms, is the clinical expression of peripheral cell-mediated activation, inflammation and induction of oxidative and nitrosative stress (IO&NS) pathways and of central microglial activation, decreased neurogenesis and increased apoptosis.
As listed in the abstract, this would help explain the frequent co-existence of depression in brain disorders such as "Alzheimer's, Parkinson's and Huntington's disease, multiple sclerosis and stroke", and medical disorders such as "cardiovascular disorder, chronic fatigue syndrome, chronic obstructive pulmonary disease, rheumatoid arthritis, psoriasis, systemic lupus erythematosus, inflammatory bowel disease, irritable bowel syndrome, leaky gut, diabetes, obesity and the metabolic syndrome, and HIV infection."
The authors propose the “common denominator” in these disorders is activation of the microglial cells (the immune cells of the brain) and/or activation of the body’s “inflammation and induction of oxidative and nitrosative stress pathways” (IO&NS pathways). These “pathways function as a smoke sensor that detect threats in the peripheral and central parts of the body and signal these threats as melancholic, anxiety, and fatigue and somatic (F&S) symptoms." (emphasis added)
The authors' conclusion:
It is concluded that the activation of peripheral and / or central IO&NS pathways may explain the co-occurrence of depression with the above disorders. This shows that depression belongs to the spectrum of inflammatory and degenerative disorders. (emphasis added)
Now, for the mental health question of the decade: Is depression largely a nutritional disorder?