Differences in brain structure and function in older adults with self-reported disabling and nondisabling chronic low back pain

Abstract

Objective: The primary aim of this pilot study was to identify structural and functional brain differences in older adults with self-reported disabling chronic low back pain (CLBP) compared with those who reported nondisabling CLBP.

Design: Cross-sectional.

Participants: Sixteen cognitively intact older adults, eight with disabling CLBP and eight with nondisabling CLBP. Exclusions were psychiatric or neurological disorders, substance abuse, opioid use, or diabetes mellitus.

Methods: Participants underwent: structural and functional brain MRI; neuropsychological assessment using the Repeatable Battery for the Assessment of Neuropsychological Status, Trail Making Tests A and B; and physical performance assessment using the Short Physical Performance Battery.

Results: In the disabled group, there was significantly lower white matter (WM) integrity (P < 0.05) of the splenium of the corpus callosum. This group also demonstrated activation of the right medial prefrontal cortex at rest whereas the nondisabled demonstrated activation of the left lateral prefrontal cortex. Combined groups analysis revealed a strong positive correlation (r(s) = 0.80, P < 0.0002) between WM integrity of the left centrum semiovale with gait-speed. Secondary analysis revealed a strong negative correlation between total months of CLBP and WM integrity of the SCC (r(s) = -0.59, P < 0.02).

Conclusions: Brain structure and function is different in older adults with disabling CLBP compared with those with nondisabling CLBP. Deficits in brain morphology combining groups are associated with pain duration and poor physical function. Our findings suggest brain structure and function may play a key role in chronic pain related disability and may be important treatment targets.

Fig. 1

Screening and Enrollment Process

Fig 2

The disabled CLBP group demonstrates significantly lower white matter integrity of the splenium of the corpus callosum (p < 0.02) shown in black. (This is a single subject image in native space with eddy current and geometric distortions corrected.) Combined groups analysis demonstrates a strong negative correlation (r_s = −0.59, P < 0.02) between the white matter integrity of the splenium of the corpus callosum and total months of CLBP.

Fig. 3

The resting state fMRI subtraction map for the disabled CLBP group–nondisabled (left sagittal, coronal, and axial image set) demonstrates activation of the right medial prefronal cortex (p < 0.01: MNI −6, 58, 22: Tal −6.69, 50.38, 28.76: Brodmann area 9) whereas the nondisabled-disabled subtraction map (right sagittal, coronal, and axial image set) demonstrates activation of left lateral prefrontal cortex at rest (p < 0.01: MNI 50, 0, 22: Tal 44.99, −3.92, 24.49: Brodmann area 6).

Fig. 4

Gait-speed and white matter integrity of the left centrum semiovale (LCS) demonstrates a strong positive correlation (r_s = 0.80, P < 0.0002). The LCS is shown to the left as a single subject image in native space with eddy current and geometric distortions corrected. Gait-speed is a sensitive marker and predictor of physical and cognitive disability as well as mortality in older adults (see text).