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Brain Imaging - Unique Signatures for Every Condition
When the cold weather hits, you change the way you dress (put away the lightweight tees and pull out the wool sweaters), you rearrange your schedule to catch more sun rays (what little there are), you alter what you eat (more hots soups and stews), you enjoy the fireplace (not the pool water), and your body responds to the frosty weather with goosebumps rather than perspiration. In a similar fashion, when you develop chronic pain and other medical disorders, your body adapts with alterations in brain chemistry and function (although this generally is not a temporary change, like the seasons). Northwestern University imaging expert, A. Vania Apkarian, Ph.D., refers to this adaptation process that occurs in painful conditions as brain reorganization. It is not some behavioral aversion to discomfort (or in the foregoing analogy, cold weather), but rather, your brain's way of responding to chronic pain.
Apkarian hypothesizes that each painful condition will produce a unique signature in the brain, and if other medical conditions coexist (e.g., anxiety or depression), then brain imaging techniques will be able to pick them up as well. For example, with the use of magnetic resonance spectroscopy (MRS) and functional MRI (fMRI), he has shown that the brain alterations in a person with low back pain and anxiety will look distinctly different from a person with low back pain or anxiety alone, or neither condition.1 In other words, Apkarian and others in the field are beginning to show the individual impact of each disorder on altered brain function. What about recent findings in people with fibromyalgia? A few impressive studies are highlighted below.
- Richard Gracely, Ph.D., and Daniel Clauw, M.D., of the University of Michigan in Ann Arbor, used fMRI to study fibromyalgia patients with and without depression.2 They found that different areas of the brain were activated when patients processed the sensory dimension of pain as opposed to those that were activated for depression (viewed as the affective component of pain because it has to do with how much emotional relevance a person attaches to their pain). They concluded, "Evaluation of these sensory and affective dimensions in patients with chronic pain is likely to improve diagnosis, choice of treatment, and treatment efficacy."
- The above findings are highly relevant in light of the common prescription of antidepressants for treating fibromyalgia. A 12-week treatment trial of the antidepressant, Effexor, revealed that fibromyalgia patients with depression benefited with improved mood.3 However, the pain of fibromyalgia was unfazed by the drug.
- A separate report by Gracely and Clauw's team measured the response to experimental pain stimuli in fibromyalgia patients and healthy controls.4 Interestingly, the healthy controls rated the stimuli to be significantly more unpleasant than the patients. Distress, anxiety or depression did not influence the patient's unpleasantness ratings. The study's authors suggest that the presence of chronic pain can alter one's perception of experimental pain (perhaps as part of the brain's reorganization process), which may pale in comparison to the day-to-day pain of fibromyalgia.
- Ali Gur, M.D., of Turkey found an important cytokine chemical, IL-8, to be elevated in patients with fibromyalgia.5 Correlating this chemical with brain function, he found that fibromyalgia patients with little to no depression had higher IL-8 levels and more impaired brain blood flow than those with severe depression. In keeping with the concept that fibromyalgia and depression cause different alterations in brain function, Gur was able to tease out the chemical change caused by fibromyalgia (IL-8) and the compounding issue of feeling depressed.
In reference to the advances in technology, Apkarian and colleagues write: "We fully expect that the next generation of brain imaging studies of pain will impact clinical practice and thus contribute to decreasing pain in society."6 How realistic is this projection? Very! Apkarian published a report this year showing how a single dose of an anti-inflammatory drug produced objective improvements in arthritis and a corresponding change in brain chemistry.7
Go to the Research page in the Basic Info section of this site to obtain an overview of studies and findings.
1. Grachev ID, et al. J Neural Transm 109(10):1309-34,
2002.
2. Giesecke T, et al. Arthritis Rheum 52(5): 1577-84, 2005.
3. Sayar K, et al. Psychosomatics 46(4):340-4, 2005.
4. Petzke F, et al. Eur J Pain 9:325-35, 2005.
5. Gur A, et al. Clin Exp Rheumatol 20(6):753-60, 2002.
6. Apkarian AV, et al. Eur J Pain 9(4):463-84, 2005.
7. Baliki MN, et al. Mol Pain 1(1):32, 2005.
