Key result
Chronic low-back pain is linked to reduced effort for high rewards via altered cortico-striatal connectivity.
Why the study?
The motivational and affective properties of chronic pain significantly impact patients' lives and response to treatment but remain poorly understood, with most phenotyping tools relying on self-report.
Do chronic low-back pain patients exhibit reduced willingness to expend effort for rewards compared to pain-free controls, and is this linked to cortico-striatal connectivity?
Case-Control
Do chronic low-back pain patients exhibit reduced willingness to expend effort for rewards compared to pain-free controls, and is this linked to cortico-striatal connectivity?
Chronic low-back pain is associated with motivational anhedonia, characterized by reduced willingness to expend effort for rewards, which correlates with altered cortico-striatal functional connectivity.
May indicate motivational anhedonia in chronic low-back pain; hypothesis-generating for cortico-striatal mechanisms, needing prospective confirmation.
The motivational and affective properties of chronic pain significantly impact patients’ lives and response to treatment but remain poorly understood. Most available phenotyping tools of chronic pain affect rely on patients’ self-report. Here we instead directly studied the willingness of chronic low-back pain (CLBP) patients to expend effort to win monetary rewards available for wins at different probabilities and different levels of difficulties in comparison to matched pain free controls and obtained functional brain imaging on a sub-group of our sample to link behavior to brain properties. We aimed to specifically test for a differential relationship of the functional connectivity in reward and effort related brain networks, and measures of effort in patients and pain free controls. Consistent with the hypothesis of “negative hedonic shift” in chronic pain we observed that CLBP patients are significantly less willing than pain free controls to expend effort to go for high cost/high reward choices and their reported low-back pain intensity predicted increased effort discounting. Furthermore, patients’ task performance was directly correlated to functional connectivity between the ventral striatum and ventro-medial prefrontal cortex, which are major nodes in the reward processing network. Patients’ performance was not explained by their self-reported depressive symptoms. Our results present new behavioral evidence characterizing the nature of anhedonia in chronic pain and links it directly to cortico-striatal connectivity highlighting the role of this circuitry in the pathophysiology of chronic pain.
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Alldritt et al. (2025) conducted a case-control in Chronic low-back pain. Chronic low-back pain vs. Matched pain-free controls was evaluated on Willingness to expend effort to win monetary rewards. Chronic low-back pain patients were significantly less willing than pain-free controls to expend effort for high cost/high reward choices, linking anhedonia to cortico-striatal connectivity.
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