Arthritic pain has a strong affective component, according to the results of a current survey, published in the April issue of Arthritis and Rheumatism. British scientists found out that arthritic knee pain, but not experimental knee pain, was associated with increased activity in brain areas, that are involved in the processing of fear, emotions and in aversive conditioning. "The present study demonstrates the importance of the medial pain system during the experience of arthritic pain and suggests that it is a likely target for both pharmacologic and non-pharmacologic interventions," the authors note.
The researchers from the University of Manchester performed positron emission tomography of the brain in twelve patients with knee osteoarthritis during three different pain states: arthritic knee pain, experimental knee pain (induced by heat application) and pain free. They noticed that both pain conditions activated the entire pain matrix, at least two parallel networks of brain structures. However, arthritic pain was also associated with increased activity in the cingulate cortex, the thalamus and the amygdala.
The authors hope that their findings will stimulate partnerships between academia and pharmacological industry to develop a new class of analgesics for arthritic pain that specifically target the medial pain system. “The search for new analgesics for arthritis that act on the brain should focus on drugs that modify this circuitry”, they write. JG
Arthritis Rheum (2007); 56: 1345-54
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