Heightened protective decision-making related to physical, but not cognitive, effort in individuals with fibromyalgia

Fibromyalgia is a chronic condition involving widespread pain, fatigue, and cognitive impairment. Evidence-based interventions for fibromyalgia, such as education and exercise, often require prolonged, cognitive and/or physical effort, involving immediate costs (effort) for delayed benefits (improved pain/function). Initiation of, and adherence to, these interventions is often difficult. While assumed to reflect low motivation, these difficulties may reflect pain-related alterations in an individual’s attitudes towards effortful and delayed rewards. Here we explored whether individuals with fibromyalgia differed from age- and sex-matched pain-free controls in such attitudes. In Study 1, individuals with fibromyalgia (N=19) and controls (N=19) completed tasks offering real rewards (raffle tickets) for performing actual physical or cognitive effort or enduring real delays. Despite individualising task difficulty to each participant’s unique capacity, those with fibromyalgia required higher incentives to engage in the physical effort task (treadmill walking), especially at higher effort intensities, but showed no differences in the cognitive effort task, indicating no general motivation deficit but rather a shift in attitudes toward physical exertion. Additionally, participants with fibromyalgia showed a greater willingness to wait for rewards, particularly at lower reward levels, suggesting an increased motivation driven by rewards. Study 2, conducted online (N=43 fibromyalgia, N=139 controls), replicated these findings, reinforcing that fibromyalgia does not involve a broad motivational deficit based on reward magnitude. Instead, we found specific changes in physical effort discounting and indications of heightened sensitivity to rewards in delay discounting. These insights may help inform tailored intervention strategies for individuals with fibromyalgia.