MMN as a biomarker in Chronic Pain

Chronic pain affects millions of people and remains extremely challenging to treat. Because of this, researchers are trying to find reliable signals in the brain that could help us understand chronic pain better and guide new treatments. One such signal is called mismatch negativity (MMN) — a small, automatic brain response that occurs when we hear an unexpected sound.

In our review paper [1], we looked at all the published studies that examined whether MMN changes in people with chronic pain. After searching major medical databases, we found 17 studies, of which 7 met our criteria for detailed analysis. These studies included people with a variety of long-lasting pain conditions, and one study used a controlled method to create a long-lasting pain sensation experimentally.

Most studies measured either the size of the MMN response or the speed at which it occurred. Three studies found that people with chronic pain had smaller MMN responses, suggesting the brain may be less efficient at automatically detecting changes in sound. Two studies found slower MMN responses, which may indicate delays in how the brain processes information when pain is ongoing. A few studies reported larger MMN responses, but these seemed to be explained by people paying more attention to their pain.

Overall, this is the first review to bring together what we know so far about MMN in chronic pain. The early findings suggest that MMN might offer useful clues about how chronic pain affects the brain and could potentially help in developing new treatments. However, because only a small number of studies exist — and because we still don’t know how pain medications influence MMN — more research is needed before MMN can be considered a reliable brain-based marker of chronic pain.

Reference:

[1] Neha Ramu, Omkar Solankey, Pradeep D,  "A review on mismatch negativity in chronic pain", IBRO Neuroscience Reports, vol. 19, pp. 831-835, 2025 (pdf)

https://www.ibroneuroreports.org/article/S2667-2421(25)00169-1/fulltext