It has long been assumed that mindfulness meditation reduces stress or pain by activating a placebo response – but a new, “very painful” experiment involving heat and bare legs has shown that’s wrong.

The placebo response is thought to come from a mixture of expectation and ritual – a sugar pill triggering feel-good neuro-transmitters.

But, in fact, mindfulness meditation was found to work in a completely different and more effective way.

Using advanced brain imaging to compare mindfulness, researchers from the University of California San Diego School of Medicine found that mindfulness meditation reduces pain “by engaging distinct brain mechanisms, different from the placebo effect”.

The researchers found that mindfulness meditation “was significantly more effective at reducing pain intensity and unpleasantness compared to placebo treatments”.

In contrast, “the placebo … only reduced the brain activity pattern associated with the placebo effect, without affecting the person’s underlying experience of pain”.

“The mind is extremely powerful, and we’re still working to understand how it can be harnessed for pain management,” said Dr Fadel Zeidan, professor of anaesthesiology and Endowed Professor in Empathy and Compassion Research, and corresponding author.

“By separating pain from the self and relinquishing evaluative judgment, mindfulness meditation is able to directly modify how we experience pain in a way that uses no drugs, costs nothing and can be practiced anywhere.”

According to the American Psychological Association, mindfulness meditation has two parts: Paying close attention to the moment, and accepting without judgment what is going on.

The scorching study

The study, published in late August, involved 115 participants and consisted of two separate clinical trials in healthy participants.

The volunteers were randomly placed into groups to be given four interventions:

• A guided mindfulness meditation
• A sham-mindfulness meditation that consisted only of deep breathing
• A placebo cream (petroleum jelly) that participants were trained to believe reduces pain
• And, as a control, one group listened to an audiobook.

The researchers applied “a very painful but harmless heat stimulus to the back of the leg and scanned the participants’ brains both before and after the interventions”.

These scans show neural signatures associated with pain response. The NAPS (left) indicates the emotional experience of pain, the SIIPS-1 (centre) relates to our expectations of pain, and the NPS (right) is associated with pain intensity. Image: UC San Diego

As the pain was in play, participants’ brain activity patterns were analysed. For this, the researchers used a novel approach called multi-variate pattern analysis.

This uses machine learning “to disentangle the many complex neural mechanisms underlying the experience of pain, including those stemming from specific heat stimulus, negative emotions and pain responses that are driven by the placebo effect”.

The researchers were then able to determine if mindfulness meditation and placebo engaged similar and/or separate brain processes.

In fact, both the placebo cream and sham-mindfulness meditation lowered pain. But mindfulness meditation was significantly more effective.

Pain signals scrambled

The scans revealed that mindfulness-based meditation affects brain areas linked to self-awareness and emotional regulation, separating pain from the self.

In effect, mindfulness scrambled the pain signal.

The researchers described it as reducing “synchronisation between brain areas involved in introspection, self-awareness and emotional regulation”.

These are parts of the brain that “together comprise the neural pain signal”.

It’s thought that this pattern of brain activity is “common to pain across different individuals and different types of pain”.

In contrast, the placebo cream and sham-mindfulness meditation did not show a significant change in the neural pain signal.

Instead, these other interventions engaged entirely separate brain mechanisms with little overlap.

“It has long been assumed that the placebo effect overlaps with brain mechanisms triggered by active treatments,” said Zeidan.

“But these results suggest that when it comes to pain, this may not be the case.”

Instead, he said, these two brain responses are completely distinct.

He said this finding supports the use of mindfulness meditation as a direct intervention for chronic pain, rather than as a way to engage the placebo effect.