When you expect pain to be worse, your brain can literally turn up the volume on it. New research has mapped the exact neural pathway behind this phenomenon — the nocebo effect — revealing it’s a real biological process, not just imagination.
The Research
In a study published May 26, 2026 in Nature Communications, two independent labs — one at University of Toronto Mississauga and one at McGill University — converged on the same finding: the neurochemical cholecystokinin (CCK) drives the nocebo effect. CCK travels from the anterior cingulate cortex (ACC), which processes emotional aspects of pain, to the lateral periaqueductal gray (lPAG), a midbrain region that regulates pain sensitivity.
Using mouse models, researchers induced negative expectations in two ways: returning mice to an environment where they previously experienced pain, or allowing them to watch another mouse in pain. In both cases, the ACC-to-lPAG pathway activated, increasing pain sensitivity. Using optogenetic tools, they could artificially activate or block the circuit. Activating it amplified pain; blocking it prevented the nocebo effect entirely.
Senior author Dr. Loren Martin said, “Researchers have known for years that CCK is linked to nocebo responses in humans, but our study identifies the specific brain pathway through which this system enhances pain.” The findings provide direct physical evidence that nocebo pain is a genuine biological event.
Why It Matters
This research destigmatizes chronic pain. Many patients are told their pain is “all in their head” — but this shows the brain actively constructs amplified discomfort through specific circuitry. Understanding this pathway also opens doors for interventions that block the CCK signal to prevent pain amplification from negative expectations. For anyone with chronic pain or anxiety, knowing that your brain can physically dial up pain means you can also learn to dial it back.
What You Can Do
Mindfulness and cognitive behavioral techniques can help reframe negative expectations. When anticipating pain, try focusing on neutral sensations or positive outcomes. Simple breathing exercises (4 seconds in, 6 seconds out) can calm the ACC and reduce emotional pain processing. You can’t always control the signal, but you can influence the volume.
Source: Neuroscience News
Curious about your own brain? Take our free adaptive IQ test or try 306 brain training levels.
