Brain inflammation caused by chronic nerve pain alters activity in regions that regulate mood and motivation. This, for the first time, shows a direct biophysical link exists between long-term pain and the depression, anxiety and substance abuse seen in more than half of these patients.

These findings also point the way to new treatment options for those with chronic pain, the incidence of suicide in patients with chronic pain is second only to those with bipolar d/o. Therefore it would be wonderful to have new treatments.

Researchers found that that pain-derived brain inflammation causes the accelerated growth and activation of immune cells called microglia. These cells trigger chemical signals within neurons that restrict the release of dopamine, a neurotransmitter that helps control the brain’s reward and pleasure centers.

Morphine and its derivatives can be ineffective in treating chronic pain. This study explains why, normally morphine and its derivatives stimulate the release of dopamine, but in rats with chronic pain, administration of morphine does not cause them to produce dopamine, resulting in impaired reward-motivated behavior. However, when these rats are treated with drugs that inhibit microglial activation, they then start producing dopamine.

Next the researchers aim to look at human chronic pain, and determine whether pain derived behaviors might account for mood disorders in these patients.

This can also shed light on mood disorders that are not caused by chronic pain. Of course dopamine is an integral part of the neurotransmitter system that contributes to mood stability. It is also the main neurotransmitter involved in Parkinson’s disease. Hoping for good things to come out of this research.

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Article reference below:

Microglia Disrupt Mesolimbic Reward Circuitry in Chronic Pain

http://www.jneurosci.org/content/35/22/8442.full.pdf+html