Fibromyalgia Pain Linked to Brain Dysfunction
More recently, researchers have demonstrated disruptions in the mu-opioid binding potential in brain regions that are known to play a role in pain modulation (J. Neurosci. 2007;27:10,000-6), as well as correlations between the clinical features of fibromyalgia and hippocampal metabolite abnormalities (J. Pain 2009;10:47-52) and between dopamine metabolism and changes in graymatter density (J. Pain 2009;10:609-18).
The brain changes in fibromyalgia may have an impact on the emotional and cognitive status of fibromyalgia patients. “Fibromyalgia patients routinely complain of what they call 'fibrofog.' They can't think straight, they can't remember things, and in fact studies have shown deficits on various cognitive performance tests, particularly in working-memory capacity, long-term memory, and verbal fluency,” Dr. Bushnell said. “When our data came out showing the changes in gray matter in fibromyalgia, I started getting e-mails from patients saying, 'That makes sense. I now know why I'm feeling this way.' We don't know yet if there is a relationship there, but it's something we're studying.”
Additionally, she noted, “there has been one small study so far showing a correlation between some of the anatomical changes in the brain and cognitive deficits, which suggests that it's possible that some of these neurological and chemical changes in the brain may underlie these various symptoms” (Brain 2008;131:3222-31).
Based on the research to date, “we know that fibromyalgia patients have altered pain processing, loss of brain gray matter, changes in white matter tracts, changes in neurochemical function, and cognitive deficits,” Dr. Bushnell said. Despite all of the brain alterations, however, it's still not clear whether fibromyalgia is a primary disorder of the brain.
“It might be a consequence of early life stress or prolonged or severe stress, which in turn affects brain function and structure in some people,” she said. “More data are accumulating from chronic pain studies suggesting that the longer the pain goes on, the more anatomical changes you see in the brain, indicating that the brain changes may be related to the duration of pain, so it is probably very important that treatment begins as early as possible.”
Dr. Bushnell has served as a consultant for and received research support from several pharmaceutical companies and is a member of the speakers bureau for Eli Lilly & Co.
