Brain inflammation caused by chronic nerve pain alters activity in regions that regulate mood and motivation, suggesting for the first time that a direct biophysical link exists between long-term pain and the depression, anxiety and substance abuse seen in more than half of these patients, UC Irvine and UCLA researchers report. This finding also points to new approaches for treating chronic pain, which is second only to bipolar disorder among illness-related causes of suicide.
The study also reveals why opioid drugs such as morphine can be ineffective against chronic pain. Morphine and its derivatives normally stimulate the release of dopamine. But in research on mice and rats in chronic pain, Cahill and her colleagues learned that these drugs failed to stimulate a dopamine response, resulting in impaired reward-motivated behavior.
Treating these animals in chronic pain with a drug that inhibits microglial activation restored dopamine release and reward-motivated behavior, Cahill said. 'For over 20 years, scientists have been trying to unlock the mechanisms at work that connect opioid use, pain relief, depression and addiction,' she added. 'Our findings represent a paradigm shift which has broad implications that are not restricted to the problem of pain and may translate to other disorders.'
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Category(s):Anxiety, Depression
Source material from University of California - Irvine
