Background/Purpose: Fibromyalgia (FM) patients show accelerated age-related decrease of grey matter (GM). Similarly, brain imaging studies in other chronic pain populations suggest interaction between age and GM changes. We investigated the relationship between age and GM alterations in FM patients categorized according to age.

Methods: This female study cohort comprised 29 FM patients and 29 controls matched for handedness, education, physical activity, and socioeconomic status. The sample was split at median age (50 yrs) into younger and older groups [mean age (SD)], FM vs. controls 42.4 (5.9), vs. 43.1 (5.3), p=0.7, and 54.9 (2.8) vs.55.7 (3.7), p=0.5. FM age groups were similar for disease duration, pain intensity, and medication use.  All subjects underwent magnetic resonance imaging (MRI) in a 3T Siemens Trio scanner. T1-weighted images were obtained for GM analysis and diffusion-weighted images for interrogation of white matter.  GM was analyzed using voxel-based morphometry (VBM)  (SPM8, Wellcome Trust for Neuroimaging, London, UK), as well as cortical thickness analysis [CIVET 1.9.9. and Surfstat (MNI, Montreal, Canada)]. Diffusion data were analysed with FSL (FMRIB, Oxford, UK). For all analyses, voxel-wise differences between groups were examined using independent sample t-tests controling for age.

Results: The GM in the medial prefrontal cortex (MPFC), left superior frontal gyrus (SFG), and premotor cortex (PMC) was reduced in FM patients compared to controls.  Total GM was negatively correlated with age in FM (p=0.009), but not in controls (p=0.6). Similar relationships with age were observed for the clusters in MPFC (FM p=0.02, controls p=0.9) and SFG (FM p=0.02, controls p=0.4). Older FM patients compared to controls showed pronounced GM decreases:  patients had less GM in the MPFC/anterior cingulate cortex, right PMC, left inferior frontal gyrus (IFG), right posterior cingulate cortex, and right temporo-occipital gyrus. There were no regions where older FM patients had more grey matter. White matter adjacent to the posterior cingulate showed decreased fractional anisotropy (FA) in older FM patients. In contrast, younger FM patients showed exclusively grey matter increases compared to matched controls in the left putamen/insula, right putamen/globus pallidum, and IFG, with no region showing decreased GM. White matter adjacent to the left putamen showed increased FA.  

Conclusion:

FM-related brain changes depend on age with findings driven predominantly by older, postmenopausal patients. Younger, premenopausal patients showed regions of increased GM compared to age-matched controls, in line with previous findings in younger pain patients (Schweinhardt et al., 2008). Furthermore, GM alterations were partly paralleled by alterations of the adjacent white matter, with integrity compromised in older and increased in younger FM patients respectively.  These findings highlight the interaction between age and cerebral changes in chronic pain states.

Schweinhardt P, Kuchinad A, Pukall CF, Bushnell MC (2008) Increased gray matter density in young women with chronic vulvar pain. Pain 140:411-419.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/cerebral-grey-and-white-matter-changes-in-fibromyalgia-depend-on-patients-age/