What if chronic pain is not only an alarm in the body, but also a rhythm in the brain? This review explores whether gently matching or reshaping those rhythms could turn the volume down. Accumulating evidence shows that chronic pain is closely associated with altered neural oscillations.

The most noticeable change in patients with chronic pain is an increase in theta oscillations. But abnormality in these oscillations has not always been observed, and seemingly conflicting results about alpha oscillations and pain severity have also been reported.

Neural oscillatory modulation can therefore investigate the relationship between pain and specific frequency patterns across different conditions. Think of a group of musicians trying to play together. When their timing matches, the music can move smoothly; when it does not, the performance breaks apart.

Synchronization of oscillatory brain activity is hypothesized to facilitate information transfer across brain regions by temporally aligning neural processing. Synchronous stimulation over distant regions can increase communication between the targeted brain regions, while desynchronous stimulation has the opposite effect.

Because pain is encoded by communication across brain networks, changing that communication might help control its progression. That idea points toward stimulating the brain’s movement-and-sensation areas with an alpha rhythm as a possible approach to relieve chronic pain.

However, studies of this approach are limited, and the effect in healthy people with experimentally produced pain is inconsistent. Personalized stimulation settings might reduce variation in responses, while settings that account for the disease and how long it has been present could provide important insight into chronic pain.

Here is the more surprising possibility: pain relief may involve two brains, not just one. Neural coupling during interaction may work together with shared behavior, shared emotion, and common understanding to promote pain relief.

When stimulation was given at the same time to two people, it enhanced synchronized movement compared with mismatched or inactive stimulation. Greater movement synchronization between patient and clinician has been linked with lower reported pain and higher trust.

The review therefore considers a single-brain approach, a two-brain approach, and brain-to-brain interfaces that allow two brains to exchange decoded neural information for pain relief through interpersonal interaction. But using two-brain stimulation to change a clinician’s brain activity in ordinary clinical settings is unrealistic.

The review instead points toward understanding how distributed brain networks communicate during chronic pain. The next step is better-targeted stimulation: personalized systems could adjust stimulation to the brain’s current state and to the frequency and location linked with a particular disease.

Still, stimulation can produce longer-lasting effects that cannot be explained only by making brain rhythms match. The changes behind those lasting effects must be understood before clinical use. The review’s conclusion is cautious: despite its potential for pain control, this approach remains in its infancy and still has several problems requiring greater innovation.

Better knowledge of communication within and between brains could help develop optimal tACS approaches as a non-drug treatment for people living with chronic pain. The review suggests that brain-rhythm stimulation may reduce chronic pain, either by restoring unusual activity in one brain or by supporting synchrony between patient and clinician.

But it remains an early possibility, not a ready treatment.