June 19 (HealthDay News) -- Changes in the levels of the neurotransmitter dopamine may explain brain gray matter reductions experienced by patients with fibromyalgia, a new study suggests.

Previous research found an association between fibromyalgia and reductions in gray matter, but the cause wasn't known, the researchers wrote.

In this new study, Dr. Patrick B. Wood, of Louisiana State University Health Sciences Center-Shreveport, and colleagues used MRI to compare the brains of 30 women with fibromyalgia and 20 healthy women of the same age. Significant reductions in gray matter were found in the fibromyalgia patients, confirming previous findings.

The new study, published in the June issue of the Journal of Pain, also found that fibromyalgia patients showed a strong correlation of dopamine metabolism levels and gray matter density in areas of the brain where dopamine is known to control neurological activity.

This association between dopamine levels and gray matter density offer new information about a possible mechanism behind some of the brain abnormalities seen in fibromyalgia patients, the researchers concluded.

SOURCE: American Pain Society, news release, June 16, 2009