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Possible Causes

Dopamine – The Missing Link

The brain has multiple areas that weigh in on interpreting signals traveling up from the brainstem. The same holds true for the brain’s formulation of a response to incoming transmissions. Rather than a simple two-way road connecting the brainstem to the brain, there exists a network of freeways (called the basal ganglia) that facilitates a dialogue between all CNS processing centers above the cord.

A proper functioning basal ganglia requires a healthy supply of dopamine for transmitting information. When a person is subjected to a painful stimulus, this relay station should pour out dopamine to reduce the impact of the discomfort. In fact, higher dopamine reserves in the basal ganglia correspond to higher pain threshold levels in healthy people.

Low spinal fluid levels of dopamine and reduced pain thresholds in fibromyalgia prompted researchers to look at dopamine levels in the basal ganglia. Brain imaging showed that healthy controls poured out dopamine when subjected to pain, but this response was blunted in people with fibromyalgia. The study illustrates that dopamine release from the basal ganglia in fibromyalgia is disrupted and is likely crippling the pain processing system.

Not only is dopamine a potent analgesic in the CNS, it also plays an important role in cognition and motivation. In addition, dopamine-transmitting neurons in the brain’s hippocampus help prevent stress responses from spinning out of control. Yet, the available levels of dopamine are reduced by 30 percent in the brains of people with fibromyalgia.

Reductions in dopamine have been found in multiple regions throughout the brain by different research teams (one funded by AFSA). And the low levels aren’t a fluke because they correlate with the reduced pain thresholds and decreased gray matter in people with fibromyalgia.

None of the FDA-approved drugs for fibromyalgia work to increase brain dopamine. And, even if one were to take a dopamine-boosting medication, the high doses required are fraught with side effects. Conversely, drugs that block NMDA receptors are believed to provide pain relief by raising CNS dopamine levels, but more research is needed.

What could be causing impaired dopamine production in fibromyalgia? Research in Parkinson’s patients points to glial cell activation. This is an interesting theory, especially since the glia cells are activated in fibromyalgia (see the next article). However, the dopamine-glial cell link in fibromyalgia needs to be further explored.