A review of 200 studies on depression and inflammation has concluded that depression and inflammation fuel one another, with inflammation playing a key role in the development of depression in some people, and depression priming greater physiological responses to stress.
Moreover, depression that is caused by chronic inflammation is resistant to traditional therapy methods. However, it is more responsive to activities such as yoga, meditation, omega-3 fatty acids, NSAIDS and exercise.
The review indicates that treatment for depression needs to consider its pathway. The researcher suggests that chronic inflammation is most common in individuals who have experienced stress in their lives, including lower socio-economic status or those who experienced abuse or neglect as children. Other contributing factors are a high-fat diet and high body mass index.
If inflammation is a significant factor, it needs to be treated in tandem with the depression.
Kiecolt-Glaser, J. K., Derry, H. M., & Fagundes, C. P. (2015). Inflammation: Depression Fans the Flames and Feasts on the Heat. American Journal of Psychiatry, 172(11), 1075–1091. http://doi.org/10.1176/appi.ajp.2015.15020152