Placebo, Parkinson’s, Pain and PET: a neuroimaging perspective

In 2002, researchers at UBC, Vancouver, BC, used neuroimaging to be able to visually detect a way in which the brain processes the placebo effect. Dr. Jon Stoessl and colleagues found that the way the brain uses dopamine during the placebo effect is similar to the way the brain uses dopamine when a person is experiencing a positive “reward” feeling. This was the first time that neuroimaging had been used to look at the placebo effect. (For more details on images or descriptions of terms, please see the bottom of this post, or follow the links in blue). The chemical structure of dopamine, a chemical that transmits messages in the brain, is as follows:

The placebo effect is a phenomenon in which a person feels better due to something that is not actually known to help the person. Originally, the term came from the Latin word, as ancient physicians found that certain treatments aimed more at pleasing the patient, rather than benefiting the patient, were useful.

Recently, Oxford scientists have discovered that a placebo can work better than a drug, when given to patients suffering from pain. Patients had more reduction in pain when told that they were being given a pain reliever, than when actually given an opioid. The response in their subjective experience of pain, was substantiated by reduced activity in brain activity in pain circuits imaged via MRI. More about this research can be read in the popular press article Placebo outperforms drug in Oxford study, on the Psych Central website. Pain can be partly visualized in part in the following image comparing a healthy brain to one with chronic pain, showing areas at rest in blue, and active areas in orange:

In 2007, a new article was published in the Journal of Molecular Imaging and Biology, entitled “Understanding the placebo effect: contributions from neuroimaging.” In this review article, the authours described how the different research to date shows that there is an anatomically identifiable action for the placebo effect. The action takes place mainly in the front of the brain. Another area of the brain, called the ventral striatum, is active when a person anticipates the reward of pain relief. Interestingly, the ventral striatum is connected to limbic stuctures, which are structures related to emotion. The ventral striatum can be seen below, (1) as a drawing, (2) on MRI diffusion tensor images, and (3) on a functional MRI image:

Just last year, Dr. Stoessl and colleagues published an update on the placebo effect. Dopamine activity in the brain was measured using PET, Positron Emission Tomography. Basically, PET shows areas of activity in the brain, based on the brain’s use of a specific chemical. The specific chemical can be seen on imaging, because it has been labelled with a radioactive tracer. The tracer has a very short half-life, or in other words, is eliminated quickly, thus exposing the person to a very small does of radiation.

In the new research, the imaging allowed scientists to see people’s brains react to the suggestion that they were going to receive effective treatment. In this study, the people studied were patients with Parkinson’s Disease. The release of dopamine was seen in the striatum, an internal structure in the brain (the striatum is pictured above, and described at the end of this post). The release of the dopamine corresponded with decreased experience of symptoms of Parkinson’s Disease. Essentially, what the research showed, is that the “strength of belief of improvement” can effectively help people experience a better quality of life due to less symptoms from the illness.

So, what does this mean for the average person? An exciting aspect of this research is to consider how much our belief can affect our reality. In 2009, Scientific American published an article entitled Placebo Effect: A Cure in the Mind. In it, the author tells of a real life story of a man who was dying from cancer, and then, believing he had received a miraculous drug, was remarkably healed. His tumors actually shrunk in half. He continued to improve, and was discharged from hospital in ten days. However, later, reports in the news questioned the efficacy of this drug, and he became ill again. The doctors then re-injected him, but this time with distilled water. He then became well, until the drug was denounced publicly, after which he died in 2 days (story published in 1957, by Bruno Klopfer).

So, science is proving that the power of suggestion can have profound implications on the health of the mind and the body. More recently, researchers are finding that meditation can lead to improved immune function, decreased stress, and decreased negative emotion. The question remains, how does this apply to the average person? Beyond the realm of illness and disease, how can this effect be used to increase quality of life? Also, how can this effect be used to improve the function of your brain?

In the 21st century, it seems that we are integrating both ancient and scientific knowledge, through discoveries assisted by advanced technology. The worlds of the physical and the mind are not as far apart as rational reasoning would have had us believe, historically. Can we use this knowledge, and the power of our belief in science, to change our health, the way we think, and the way we behave and live, more quickly than we have in the past?

An intense curiousity remains, as to how deeply we can change, given an integrated understanding of how to use our minds and our beliefs to change our behavior, our lives, and our connections to each other and the planet. Although this is a tangent from the research above, we are living in a time of noticeable changes to the planet (see Crossroads for Planet Earth). Given the current climate of our existence, I wonder how current research can change the way that humans behave on the planet. Not an easy question to answer, but an important one.




Dopamine: Dopamine is a chemical that is produced in several places in the brain. Dopamine is associated with various brain activities. It is also thought to be connected to whether a person anticipates reward or not. As anticipation of reward influences behaviour choices, dopamine is a brain chemical of high interest.

Healthy brains versus those in chronic pain: The second image above is from an article in Science Daily, which talks about the decrease in activity in the brain in people  who have chronic pain. It is one of the similar images demonstrating how very different the healthy brain is from the brain experiencing pain. The blue areas show areas at rest, and the orange areas are active areas. Basically, the person in pain has an overactive brain, that then tires out. For more information, see the article.

Ventral striatum images: (1) the ventral tegmentum, as seen in your brain, with the front of your brain located to the right of the computer screen, and the back in the deeper pink colour. (2) Diffusion tensor and stereotactic images of the ventral striatum, and its connection to the ventral tegmentum, brainstem, orbitofrontal cortex, insula, cingulate cortex and mesolimbic structures. The image is from Medscape. (3) This image shows the ventral striatum being activated when the person is looking at an attractive face. The image is an fMRI image from an article in Nature.

Striatum: The striatum is a structure deep inside the brain. Primarily, the striatum modulates movement, but it also has an effect on executive function. The image in this post is from the Biotechnology Industry Organization.

More reading:

The Cure Within: A history of mind-body medicine. 2008. Authour: Anne Harrington, Harvard College professor and Professor for the History of Science.

The Biology of Belief: unleashing the power of consciousness, matter and miracles. 2005. Authour: Bruce H. Lipton, former medical school professor and research scientist.