Opioid resistance in fibromyalgia patients explained
A recent study has shed new light on opioid resistance in fibromyalgia patients. According to Richard E. Harris, Ph D., of the University of Michigan, and colleagues, opioid resistance in fibromyalgia can be explained by lessened receptor activity in areas of the brain that respond to pain. The study, published in the September 12th Journal of Neuroscience, also found a correlation between reduced receptor function in fibromyalgia patients and depression. The study focused on 17 right-handed women with a mean age of 44.8 suffering from fibromyalgia and 17 sex and age matched controls. The following is an excerpt of an article from medpage today that reviews this fascinating study:
Because these receptors are the target of opiate drugs,” they wrote, “a profound reduction in the concentration or function of these receptors is consistent with a poor response of fibromyalgia patients to this class of analgesics, observed anecdotally in clinical settings.”
The researchers used PET with a selective µ-opioid receptor radiotracer to assess receptor availability differences between fibromyalgia patients and healthy pain-free individuals.
Their study included 17 right-handed women with fibromyalgia (mean age 44.8, mean diagnosis duration 8.4 years) and 17 age- and sex-matched healthy controls who were part of an ongoing study of acupuncture treatment. The analysis was done on PET scans and other data collected at baseline.
No participants were taking opioids or had a history of their use. Of the 17 fibromyalgia patients, 10 were taking antidepressant medication, either serotonin reuptake inhibitors or dual serotonin/norepinephrine reuptake inhibitors.
The women reported “sensory” and “affective” characteristics of their pain on the Short Form of the McGill Pain Questionnaire immediately prior to undergoing the PET scan.
Depressive symptoms were self-reported on the Center for Epidemiological Studies-Depression Scale, which is used to detect major or clinical depression.