Arthritis & Rheumatism, Volume 60,
October 2009 Abstract Supplement

The 2009 ACR/ARHP Annual Scientific Meeting
Philadelphia October 16-21, 2009.


Glutamate in the Anterior Insula Is Associated with Working Memory Performance in Fibromyalgia (FM)

Barjola1,  Paloma, Glass2,  Jennifer, Sundgren2,  Pia, Harte2,  Steven E., Williams2,  David A., Clauw3,  Daniel, Harris2,  Richard

Rey Juan Carlos, Madrid, Spain,
U. Michigan, Ann Arbor, MI,
University of Michigan, Ann Arbor, MI

Purpose:

Glutamate (Glu) is an excitatory neurotransmitter whose concentration within the posterior insula has been shown to be related to pain processing in fibromyalgia (FM) (Harris et al. 2008). The role of Glu in the anterior insula in FM is less understood. Since FM is also associated with multiple cognitive impairments such as reduced working memory (WM), and insular structures have been previously shown to be involved in different aspects of memory function, we hypothesized that anterior insular Glu may be related to WM performance.

Method:

19 FM patients (age 45.2 (15) yrs) participated in a session of H-MRS and single-voxel spectroscopy (SVS) was performed using the following parameters: PRESS, TR 3000ms, TE 30 ms, 90° flip angle, NEX 8, FOV 16cm, and VOI of 2×2×3cm. Two separate SVS sequences were performed, one with the VOI placed in the right anterior insula and another in the right posterior insula. Patients were at rest during the session. Values for Glu were calculated as absolute concentration using water signal as an internal reference, and expressed in arbitrary institutional units (AIU). Raw data were analyzed with LCModel software. WM performance was assessed with the Letter-Number span test (Wechsler Memory Scale). Additionally, reported pain was assessed with the McGill Pain Questionnaire (MPQ). Data were analyzed with SPSS v17.

Results:

Concentrations of Glu in the right anterior insula were positively correlated with WM performance (r=0.626; p=0.004). The sensory subscale, but not the affective subscale, of MPQ was negatively correlated with the scores in WM (r=-0.495; p=0.037). A stepwise linear regression model with WM performance as a dependent variable was carried out. In the first step pain showed significance as a predictor (p=0.037) of WM (worse pain was associated with worse WM). When both pain and Glu levels were entered as simultaneous predictors, the effect of Glu was significant (p=0.014) and pain displayed a trend towards significance (p=0.104). No such relationships were detected for the right posterior insula.

Conclusion:

Consistent with previous literature, the anterior and posterior regions of the insula appear to be functionally distinct. This study suggests that anterior insula Glu may be involved in WM whereas previous studies suggest that the posterior insula is involved in pain processing. Future studies are needed to understand the mechanisms underlying these relationships which may be relevant to other chronic pain populations.

To cite this abstract, please use the following information:
Barjola, Paloma, Glass, Jennifer, Sundgren, Pia, Harte, Steven E., Williams, David A., Clauw, Daniel, et al; Glutamate in the Anterior Insula Is Associated with Working Memory Performance in Fibromyalgia (FM) [abstract]. Arthritis Rheum 2009;60 Suppl 10 :1993
DOI: 10.1002/art.27065

Abstract Supplement

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