Depression triggered by chronic inflammation

April 17, 2009 by  
Filed under featured, Medical Research & Studies


It’s well known to doctors that patients with chronic inflammation, such as that linked to coronary heart disease or rheumatoid arthritis, are more likely than others to become depressed. Some pro-inflammatory drugs, such as interferon-alpha, which is used to treat Hepatitis C and a cancer known as malignant melanoma, also induce symptoms of depression in a significant number of patients, as does treatment with antibiotics.

What they haven’t known is why, but now researchers at the University of Illinois have discovered that IDO (indoleamine 2,3 dioxygenase), an enzyme found throughout the body and long suspected of playing a role in depression, seems to act as a molecular switch and is in fact essential to the onset of depressive symptoms sparked by chronic inflammation.

The researchers knew that infection causes immune cells to produce cytokines, signaling proteins that help the body fight infection. These proteins also activate IDO in the body and brain. IDO degrades the amino acid tryptophan, which is the precursor of serotonin, a brain chemical known to positively influence mood. The researchers suspect that the metabolites produced when IDO degrades tryptophan are in some way promoting depression and this opens the way to research further into how to inhibit this behaviour and pre-empt depression.

For years, no one considered that an infection somewhere in the body could affect the brain, but we now know that the immune system is a sensory organ and is perfectly adapted to ‘see’ infectious agents. It then communicates that information to the brain so proving that there is a clear link between the immune system and the nervous system.

If you have a tendency towards depression, it can help to know how to combat any potential downward spiral if you have a chronic infecitopn, or are taking antibiotics. St John’s Wort is helpful to many, as is taking additional B complex and vitamin C to both help the immune system and help mood elevation. Keeping the immune system healthy and strong is a priority with a good diet, low sugar intake, regular cupuncture and herbs such as Echinacea to keep on top of any potential down swings.