Research from the University of Michigan Health System says that patients who have Fibromyalgia were found to have reduced binding ability of a type of receptor in the brain that is the main target for opiod painkiller drugs. Opioid pain killers work by binding to opioid receptors in the brain and spinal cord. Examples of opiod painkillers include morphine, codeine, Darvocet (propoxyphene-containing medications), Vicodin (hydrocodone-containing medications), and Oxycontin (oxycodone-containing medications).
PET Scans of the brains of Fibromyalgia patients showed that the fibromyalgia patients had reduced mu-opioid receptor (MOR) availability within regions of the brain that normally process and dampen pain signals.
Researcher and lead author for this study, Richard Harris, PhD, said:
“The reduced availability of the receptor was associated with greater pain among people with fibromyalgia. These findings could explain why opioids are anecdotally thought to be ineffective in people with fibromyalgia. The finding is significant because it has been difficult to determine the causes of pain in patients with fibromyalgia, to the point that acceptance of the condition by medical practitioners has been slow.”
The PET scans also showed that the FM patients with more depressive symptoms had reductions of MOR binding potential in the amygdala, a region of the brain thought to modulate mood and the emotional dimension of pain.
The study subjects included 17 women with Fibromyalgia and 17 healthy female women.