People living with chronic pain may exhibit reduced cognitive function and find it harder to concentrate, possibly due to resources being diverted to process the pain. However, the level of cognitive impairment (or ‘brain fog’) can vary across individual patients. In a recent study, Francesca Storey and colleagues use a technique called electroencephalography (EEG) to measure the brain activity of neurotypical participants as they complete a cognitive task. By using capsaicin (the same compound found in chili peppers) to induce a pain response, the researchers compare how participants perform in the task when in pain, and when pain-free. They go on to compare the brain activity of participants who performed worse when in pain with those who performed better when in pain. Their results suggest that these two groups differ in their ability to inhibit brain regions that have been implicated in the processing of painful stimuli processing, with participants who performed better when in pain diverting fewer cognitive resources to these potential pain-associated regions.

Overall, Francesca’s work improves our understanding of how chronic pain and brain fog are linked, and provides insights into why some individuals can maintain focus during pain while others find it more difficult. “These insights are particularly important for advancing research into cognitive dysfunction in chronic pain – a commonly reported symptom often referred to as ‘brain fog’,” Francesca explained. “The results may help guide the development of interventions aimed at enhancing or restoring this neural strategy.”

The project also shows the importance of careful study design. “One key breakthrough came while considering how best to design my study to test the hypothesis,” Francesca said. “I realised that simply comparing pain and no-pain conditions would average out individual differences, potentially masking important effects. By instead dividing participants into two groups—those who performed ‘better’ and those who performed ‘worse’ under pain—I uncovered distinct differences in brain activity between them. This highlighted the risk that generalised study designs may overlook meaningful findings, particularly in fields like this where there is a great degree of individual variation.”

Francesca completed this research with Professor Ali Mazaheri at the University of Birmingham, and she is now an Academic Clinical Fellow in Geriatrics at King’s College London. As part of her fellowship, she hopes to apply her expertise in EEG analysis to studying the ageing brain, specifically, attempting to understand the brain processes underpinning delirium and cognitive dysfunction in older age.

 

'Individual differences in cognitive performance under pain linked to region-specific alpha power modulations' (Storey et al.) (DOI 10.1016/j.ynpai.2025.100196) was published in Neurobiology of Pain.