It's not clear yet, to me at least, if the inflammation causes the disease or is simply a symptom of the disease, the way we get a runny nose due to our immune system fighting off invading allergens.
However, the experience of frequent and prolonged immune system response - as is seen in chronic stress - activates the "immune-to-CNS circuitry" designed to fight injury or infection, but can also lead to neuroinflammation, something we were not designed to withstand.
Still, we know that DHA, an omega-3 fat found in fish oil, luteolin (found in foods like carrots, peppers, celery, peppermint, rosemary, chamomile, and olive oi), and curcumin all reduce the inflammatory response in both the body and the brain. So a healthy diet can offset some of the damage created by chronic stress.
Here is the beginning of the article. It is available online and can be downloaded as a PDF. I have included their list of further reading at the bottom.
Steven F. Maier, Ph.D. and Linda R. Watkins, Ph.D., University of Colorado at BoulderAugust 2012
Conditions as varied as surgery, cancer chemotherapy, peripheral nerve damage, and heart attack can lead to poor memory, depression, fatigue, and exaggerated responses to pain. The common feature of these conditions of the body is that they induce inflammatory responses in the body, outside the central nervous system (the CNS which consists of the brain and spinal cord only). However, the cognitive and emotional effects that inflammatory responses lead to are nevertheless accomplished through the CNS. Memory, mood, activity, and pain are direct products of CNS activity, and not the peripheral immune system.
Steven F. Maier, Ph.D.University of Colorado at Boulder
Linda R. Watkins, Ph.D.University of Colorado at Boulder
Until recently the CNS and peripheral immune system were thought to operate independently. Indeed, you cannot find the term “immune system” in the indexes of current major texts in neuroscience nor the terms “CNS” and “brain” in the indexes of major texts in immunology. However, new research has led to important advances in our understanding of how immune-related events in the periphery can influence CNS processes, thereby altering cognition, mood, and behavior, and these advances are suggesting that inflammation may have important long term implications for the brain.
- Maier, S. F. (2003). Bi-directional immune-brain communication: Implications for understanding stress, pain, and cognition. Brain, Behavior, and Immunity, 17, 69-86. (Abstract only.) (Full text; payment required.)
- Dantzer R., O'Connor J.C., Freund G.G., Johnson, R.W., and Kelley K.W. (2008). From inflammation to sickness and depression: when the immune system subjugates the brain.
- Nature Reviews Neuroscience, 9, 46-56. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2919277/pdf/nihms213147.pdf
- Barrientos, R. M., Frank, M. G., Watkins, L. R., & Maier, S. F. (2010). Memory impairments in healthy aging: Role of aging-induced microglial sensitization. Aging and Disease, 1, 212-231.
- Dantzer, R( 2001) Cytokine-induced sickness behavior: mechanisms and implications Annals of the New York Academy of Sciences, 933, 222-234. (Abstract only.) (Full text; registration and payment required.)