NEW YORK (Reuters Health) – Dysfunction in a portion of the brain may explain some of the symptoms of fibromyalgia syndrome, researchers suggest in a paper published in the Journal of Rheumatology

Dr. Yasser Emad, of Cairo University, Egypt, and colleagues used proton magnetic resonance spectroscopy to examine the function of the hippocampus in 15 patients with fibromyalgia syndrome and in10 healthy women who were the same age as the other patients.

The hippocampus is located deep in the front portion of the brain involved in regulating emotions and memory. Functionally, the hippocampus is part of the olfactory cortex, which is important to the sense of smell. The name is from the Greek hippos (horse) = kampos (a sea monster), based on its shape, which resembles a seahorse.

Using spectroscopy, the researchers calculated levels of hippocampus levels of the brain chemicals N-acetyl aspartate (NAA), choline, creatine, along with their ratios, and compared the findings between the two groups. All study participants also underwent assessments of sleep patterns, cognitive function, and symptoms of depression. The number of tender points on the body was assessed in all patients and a visual analog scale was used to measure pain.

Patient age averaged 35.7 years, and their average disease duration was 18.1 months. All of the patients had cognitive functional impairments on the Mini-Mental State Examination, eight (35.5 percent) were depressed according to the Hamilton Depression Scale, and nine (60 percent) had sleep disturbances. None of the control subjects had any problems in these areas.

“NAA levels of the right and left hippocampi were lower in the patients compared to controls,” Emad’s team explains. “Another statistically significant difference was observed in choline levels in the right hippocampus, which were higher in the patient group.” The fibromyalgia patients also had significantly lower NAA to choline and NAA to creatine ratios compared with the control subjects.

There were no differences between the groups in other metabolites measured or in the choline to creatine ratio.

In the patient group, language scores were significantly correlated with choline and creatine levels, but there was no significant correlation between the levels of the metabolites or their ratios and the number of tender points.

“The hippocampus was dysfunctional in patients with fibromyalgia, as shown by lower NAA levels,” the investigators conclude.

Because the hippocampus has a critical role in maintaining cognitive functions, sleep regulation, and pain perception, the researchers suggest that metabolic dysfunction of hippocampus may be implicated in the symptoms of this puzzling syndrome.

SOURCE: Journal of Rheumatology, July, 2008.