Chronic Back Pain Rewires the Brain's Sound Processing - And a Psychological Therapy Can Reverse It

Patients with chronic back pain often report that ordinary sounds feel harsher than they should - that a conversation at normal volume feels grating, or that background noise is disproportionately difficult to filter. For years, this complaint occupied an uncertain clinical space: was it a real phenomenon, a side effect of chronic pain's toll on mood and attention, or something else entirely?

A brain imaging study from the University of Colorado Anschutz, published in Annals of Neurology, provides one of the first concrete, neurological answers to that question. People with chronic back pain process everyday sounds differently, and more intensely, than people without pain. The differences are visible in brain scans, measurable against a control group, and - crucially - responsive to treatment.

What the Brain Scans Showed

The study enrolled 142 adults with chronic back pain and 51 pain-free controls. All participants underwent brain imaging. During the MRI sessions, researchers had participants listen to sounds while measuring their subjective discomfort ratings and the strength of neural responses in key brain regions.

The differences between chronic pain patients and healthy controls were large. On average, chronic back pain patients reacted more strongly to sounds than 84% of people without pain - a substantial effect that cannot be attributed to individual variation alone.

The brain scan data showed where this amplification is happening. The changes were not occurring in primary auditory processing areas - the earliest stages where the brain detects sound. Instead, the alterations appeared higher up in the processing hierarchy: in the auditory cortex, which processes the loudness and quality of sound, and in the insula, which processes the emotional and bodily significance of sensory input. Simultaneously, the researchers observed lower activity in the medial prefrontal cortex - a region involved in regulating and dampening unpleasant experiences.

The pattern is consistent with a broader "sensory amplification" hypothesis of chronic pain: that persistent pain does not merely occupy one sensory channel but dysregulates sensory processing more broadly, increasing sensitivity across multiple systems beyond just the site of injury.

"Our findings validate what many patients have been saying for years - that everyday sounds genuinely feel harsher and more intense. Their brains are responding differently, in regions that process both the loudness of sound and its emotional impact," said Yoni Ashar, PhD, assistant professor of internal medicine and co-director of the Pain Science Program at CU Anschutz, the paper's senior author.

Testing Three Treatments

The study did not simply document the neural abnormalities; it tested whether they could be corrected. Participants with chronic back pain were randomly assigned to one of three groups: Pain Reprocessing Therapy (PRT), a placebo condition involving a saline injection given in a supportive clinical context, or usual care in which participants continued whatever treatments they were already receiving.

Pain Reprocessing Therapy is a psychological intervention that helps patients reframe their experience of pain - reconceptualizing it as a product of the brain's amplified signaling rather than a direct indicator of ongoing tissue damage. Previous research from Ashar's group had found that two-thirds of chronic back pain patients treated with PRT became pain-free or nearly so, compared to roughly 20% improvement in a placebo group.

In this study, PRT was the only treatment that significantly reduced the heightened brain response to sound, while also increasing activity in brain regions that regulate unpleasant experiences. Neither the placebo nor usual care produced these neural changes.

Open Questions and Next Steps

The study raises questions it does not yet answer. Does heightened sensory sensitivity precede chronic pain, making some people more likely to develop persistent pain after an injury? Or does it develop as a consequence of sustained pain? Early data from other research groups suggests the former may be true for some individuals, but the causal direction has not been established definitively.

The research team plans a follow-up study testing whether the sensory amplification extends to other modalities - light, smell, taste - and whether a single central brain mechanism drives all of these sensory shifts. If so, that would suggest a more unified target for intervention than the current evidence base implies.