General Neuroscience

The Neurology Behind The Placebo Effect

Anushka Sarda


Abstract

The power of mind over matter has fascinated scientists and doctors for decades. Naturally, we associate treating diseases with beneficial outcomes, allowing even placebos ─nonfunctional treatments─ to stimulate pain relief. In the past, the placebo effect has been coined a sham, but studies have proved that  placebos often have as much of an impact as actual medication. Placebos have been used for decades, commonly as a control to test the effectiveness of new medicine. Recently, researchers have been studying the exact cause and the neurology behind the placebo effect through a series of experiments brought to light by this article.  

 

What is the Placebo Effect?

    A placebo is a substance or treatment that has no actual therapeutic effect. When given to  a patient who is told that the treatment is legitimate, a placebo can result in positive effects [1]. Placebos are used to test the effectiveness of a treatment or drug on a certain condition by comparing the effects of the treatment and the placebo on participants in a study [1]. The participants’ response to the placebo, positive or negative, is known as the placebo effect [1].

    The placebo effect consists of a patient’s brain convincing their body that an innocuous treatment is real,  in effect stimulating healing responses[2]. A placebo cannot cure a condition, but rather will alleviate one’s perception of symptoms.. Historically, placebos have been effective in aiding pain management, stress-related insomnia, fatigue, and nausea [2]. Additionally, the use of a placebo can often result in negative, unanticipated side effects[3].

    Further research of the placebo effect reveals that its effects are only prevalent when the patient thinks they are receiving a functional treatment, and expects a positive outcome. Placebos seem to be ineffective when patients in a study are given placebo medication without their knowledge [3].

 

Neurology

    A recent study of Parkinson’s disease found that patients whose conditions improved due to a placebo displayed identical neurological changes  as patients who received the actual medication, which increases dopamine levels. Although traditional expectations led many to believe that the placebo treatment should not have caused an increase in dopamine levels, it did, enabling the patients to feel relief [3].

    Another study used a magnetic resonance imaging (MRI) machine to scan and observe the brains of patients with chronic pain suffering from knee osteoarthritis. Their neural activity was then scanned again after each patient was given a placebo. It was noted that the patients who felt relief from their knee pains had increased brain activity in the middle frontal gyrus region in the frontal lobe, implying the involvement of this region in the placebo effect [2].

    Research shows that analgesia due to a placebo is caused by the activation of the endogenous opioid analgesia network, a congenital pain-relieving system consisting of scattered neurons that produce pain-relieving opioid neurotransmitters [3][5].

 

Benefits to Medicine

    The expected benefits from medication, whether it be placebo or real, is what activates the neural pathways. Further study of these mechanisms and commercial use of them in clinics would allow patients to feel relief without experiencing the side effects of medications [3].

    The discovery of the relationship of the placebo effect to endogenous systems of analgesia has birthed a new line of research dealing with the biochemical and neurophysiological mechanisms and their neuroanatomical localization. Until recently, the only study relating to the endogenous systems of analgesia was stress-induced analgesia. Further placebo research will provide us with a better understanding of the endogenous systems of analgesia [6].


References


  1. Benedetti, F. (2006). Placebo and the Endogenous Mechanisms of Analgesia. SpringerLink. https://link.springer.com/chapter/10.1007/978-3-540-33823-9_14. Retrieved: 01/27/18.

  2. Holden, JE. Jeong, Y. Forrest, JM. (07/05). The endogenous opioid system and clinical pain management. PubMed. https://www.ncbi.nlm.nih.gov/pubmed/16082232. Retrieved: 01/27/18.

  3. Friedman, Joseph H. Dubinsky, Richard. (08/25/08). The placebo effect. American Academy of Neurology. http://n.neurology.org/content/71/9/e25. Retrieved: 01/21/18.

  4. Cavanna, AE. Strigaro, G. Monaco, F. (04/07). Brain mechanisms underlying the placebo effect in neurological disorders. PubMed. https://www.ncbi.nlm.nih.gov/m/pubmed/17637211/.

  5. (05/17). The power of the placebo effect. Harvard Health Publishing. https://www.health.harvard.edu/mental-health/the-power-of-the-placebo-effect. Retrieved: 01/21/18.

  6. Ratini, Melinda. (02/23/16). What is the Placebo Effect?. WebMD. https://www.webmd.com/pain-management/what-is-the-placebo-effect. Retrieved: 01/18/18.

Anushka Sarda

Anushka Sarda


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