Uncovering brain mechanisms of impaired working memory in older adults with chronic low back pain

Research output: Unpublished conference presentation (presented paper, abstract, poster)Conference presentation (not published in journal/proceeding/book)Academic researchpeer-review

Abstract

Introduction. Impaired working memory is present in some people with chronic low back pain (CLBP). Functional magnetic resonance imaging (fMRI) has revealed abnormal brain activity in the working memory-related brain regions, uncovering potential brain mechanisms of impaired working memory in CLBP. However, these studies were limited to only middle-aged adults (from 46 to 53 years) with CLBP and employed tasks that were not designed to specifically probe working memory (i.e., resting-sate functional connectivity (FC) or attention tasks). The presence of aberrant brain activity in older people with CLBP is unclear, especially in tasks that are designed to assess working memory-related brain activity.

Aim. To investigate whether older adults with CLBP showed altered resting-state and working memory-related brain activity compared to demographically-matched healthy controls (HCs).

Methods. Older adults with CLBP (n=18, 68.9±2.6 years) and demographically-matched HCs (n=20, 68.6±3.6 years) underwent fMRI scans at rest and during a 2-back working memory task. Resting-state fMRI was assessed using amplitude of low-frequency fluctuations (ALFF) and FC during between 11 regions of interest (ROIs) in the default mode network (DMN) and central executive network (CEN) selected a priori. Independent two-sample t-tests were performed to identify between group differences in the 2-back task activity, ALFF, and FC. Family-wise error corrected and Gaussian random field corrected p-values were used as the threshold for statistical significance. Next, we used multiple linear regression to test the association between the fMRI measures and working memory performance.

Results. General cognition, measured by MoCA, did not statistically differ between the CLBP participants and HCs (p>0.05). Compared to HCs, participants with CLBP showed significantly lower visual cortex activity during the 2-back task and significant lower 2-back task performance (p = 0.014). Further, CLBP participants with higher pain intensity (≥4 on visual analogue scale) demonstrated significantly lower activity in the left dorsal lateral prefrontal cortex (DLPFC) than HCs. At rest, participants with CLBP exhibited significantly lower ALFF in the left inferior temporal gyrus than HCs. Additionally, FC between DMN and bilateral DLPFC was higher in CLBP participants. Multiple linear regression showed that higher FC between the posterior cingulate cortex (part of DMN) and left DLPFC (part of CEN) were associated with lower performance in the 2-back task among participants with CLBP (adjusted R2 =0.948, β = -0.34, p =0.003).

Conclusion. We uncovered potential brain mechanisms underlying impaired working memory in older adults with CLBP. Poor working memory performance in older adults with CLBP may be attributed to inadequate visual cortex activity because the visual cortex is involved in working memory storage and can protect working memory processes from distraction. The inverse relationship between the DMN and CEN may also contribute to the poor working memory in older adults with CLBP. For older adults with high-intensity CLBP, their working memory capacity may be further affected by decreased DLPFC activities. Future studies should evaluate whether older people with CLBP are at risk of developing cognitive impairment.
Original languageEnglish
Pages49
Number of pages1
Publication statusPublished - May 2023
EventSpineweek 2023 - Melbourne, Melbourne, Australia
Duration: 1 May 20235 May 2023
https://www.spineweek.org/

Competition

CompetitionSpineweek 2023
Country/TerritoryAustralia
CityMelbourne
Period1/05/235/05/23
Internet address

Keywords

  • brain changes
  • low back pain
  • older adults
  • working memory

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