Do placebos work on you? Now we can find out

The area of the brain responsible for the placebo effect has been pinpointed for the first time. The findings may lead to extra treatment options for people suffering from chronic pain.

The brain region that lights up in some people when a fake treatment was found using fMRI brain scans, according to a paper published in PLOS Biology. The area is called the mid-frontal gyrus and lit up in the placebo responders.

About half of patients in the study felt markedly less pain when given a placebo painkiller for chronic knee pain from arthritis. The scans showed that in those people who felt better, a region of the brain called the right mid-frontal gyrus responded to the placebo pill.

The response in this brain region could even predict the scale of the pain relief that the patient reported, the authors say. Additionally, the researchers found a region of the brain that predicts the patient's response to painkiller drugs. Scanning the brains of people suffering from chronic pain to see whether they respond to placebo painkillers and painkiller drugs could help doctors personalise the patient's treatment options.

"The new technology will allow physicians to see what part of the brain is activated during an individual's pain and choose the specific drug to target this spot," says study co-author Vania Apkarian, professor of physiology at Northwestern University's Feinberg School of Medicine in the US. "Physicians will be able to measure how the patient's pain region is affected by the drug."

This could be a particular benefit for people suffering from chronic pain, for which addictive painkillers – such as morphine – can be a poor long-term option.

"Given the enormous societal toll of chronic pain, being able to predict placebo responders in a chronic pain population could both help the design of personalised medicine and enhance the success of clinical trials," said Marwan Baliki, a researcher at Feinberg and at the Rehabilitation Institute of Chicago, and co-author of the study.

The findings add weight to the growing evidence that the placebo effect – at least in pain relief – has a biological basis in the body, a claim that has been contested for decades.