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The Placebo Effect and God May Live in the Same Brain Region

An ancient brainstem region evolved to help us to believe the unbelievable.

Key points

  • The perception of pain, more than any other sensory experience, is powerfully influenced by our expectations.
  • Devout Catholics perceive noxious electrical pulses as being less painful when they gazed on a representation of the Virgin Mary
  • The periaqueductal gray within the brainstem became active when the subjects reported less pain after using a placebo.
  • A person’s feelings of spirituality or religiosity also depend on increased activity within the periaqueductal grey region.

The perception of pain, more than any other sensory experience, is powerfully influenced by our expectations. This is the essence of the placebo effect. Apparently, it is also influenced by our beliefs.

Can looking at a picture of the Virgin Mother relieve pain? Yes. However, you need to be a devout practicing Catholic for this to work. In a study published a few years ago in the journal Pain, devout Catholics reported feeling more peaceful and compassionate when they looked at a picture of the Virgin Mary than when they looked at the painting of “Lady with an Ermine” by Leonardo da Vinci. Devout Catholics also perceived noxious electrical pulses to their hand as being less painful when they gazed at a representation of the Virgin Mary than when they looked at the painting by da Vinci. Professed atheists and agnostics did not benefit from viewing an image of the Virgin Mary or the painting by da Vinci. They simply felt the pain. fMRI scans demonstrated that the Catholics’ pain relief was associated with greatly increased brain activity in brain regions involved in controlling our emotional response to pain.

A pair of recent studies investigated the brainstem pathways involved in the phenomena of placebo analgesia. These studies used functional MRI (fMRI) to resolve the brainstem circuits that become active during the generation of placebo analgesia. In one study, healthy human participants were deceptively conditioned to believe that a cream labeled “lidocaine” would reduce the pain induced by a noxious stimulus. The cream did not contain lidocaine. Pain intensity ratings were collected from each subject. fMRI analysis revealed a well-known pain modulatory system that included the periaqueductal gray pathway within the brainstem that became active when the subjects reported less pain after using the cream labeled with the word lidocaine.

Another study discovered that a person’s self-reported spirituality or religiosity was also centered on this same brainstem region that included the periaqueductal grey. The periaqueductal grey is an ancient structure that has been shown to play an important role in our response to fear, pain, and altruistic behavior. Interestingly, injury to this brainstem region causes delusional thinking. The periaqueductal grey, and its related circuitry, may have evolved to encourage altruistic behaviors and to reduce the fear of living in an unpredictable world.

These recent studies suggest that one’s degree of spirituality and the placebo effect are functionally linked within the periaqueductal grey region within the brainstem. However, for them to be effective you have to follow the instruction offered by Tinker Bell: you just need to believe.

References

Crawford LS et al (2021) Brainstem mechanisms of pain modulation: a within-subjects 7T fMRI study of placebo analgesic and nocebo hyperalgesic responses. J Neuroscience Vol 41 (47) 9794-9806; DOI: https://doi.org/10.1523/JNEUROSCI.0806-21.2021

Ferguson MA et al (2021) A neural circuit for spirituality and religiosity derived from patients with brain lesions. Biological Psychiatry 2021DOI:https://doi.org/10.1016/j.biopsych.2021.06.016

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