How Your Mind Can Impact Your Immune System

image: iStock photo

PCDR stands for Placebo Controlled Dose Reduction. It is where a drug is gradually replaced by a placebo by making incremental reductions in the drug while making incremental increases in the placebo.

One of the most successful demonstrations was by Fabrizio Benedetti at the University of Turin School of Medicine. Over the period of 5 days, he was able to swap the anti-Parkinson’s drug, apomorphine, for a saltwater placebo. On the first day, the placebo had no effect, as measured by tremors, changes in muscle stiffness and activation of individual neurons in the brain. But by day 5 of giving people a dose of apomorphine and then swapping for a placebo, the placebo generated a clinical and neurological effect equivalent to a full dose of the drug.

What happened in those 5 days?

Each day that a patient receives their injection, they gain experience that, “When I receive this injection, the following things happen.” That is, a reduction in tremors and muscle stiffness, plus the neuroscientists observe corresponding activation of neurons in the brain. Each day strengthens their experience and thus strengthens their belief.

One of the most important advances in the neuroscience of the placebo effect is that in studies so far, belief, or expectation, shifts biochemistry, causing the brain to produce what it needs to produce to deliver the result the person believes is supposed to happen. Experience strengthens beliefs, so with PCDR, the weight of their experience is enough to allow the complete replacement of the drug with the placebo.

The same kind of thing has been done with the immune system. With the goal in mind of supressing the immune system for the potential treatment of organ transplant patients or people with autoimmune conditions, scientists have been able to completely replace an immunosuppressant drug with a placebo over about 4 or 5 days.

This shows us that the mind can impact the immune system. In this case, supressing it. Can the mind also boost the immune system?

The Mother Theresa Effect is the name given to the observation where over 100 volunteers watched a video of Mother Theresa on the streets of Calcutta carrying out acts of compassion and kindness. Our state when we observe compassion and kindness is often referred to as elevation, in that compassion and kindness induce an elevated state.

Scientists measured levels of an important immune system antibody known as secretory immunoglobulin A (s-IgA) before and after. At the end of the video, levels of s-IgA had increased by around 50% and stayed high for a time afterwards as the volunteers continued to feel elevation as they discussed what they had witnessed in the video. Feeling elevated seemed to elevate the immune system.

Research by the HeartMath Institute in Boulder, Colorado, showed something similar. Asking volunteers to generate and hold feelings of care and compassion for about 5 minutes, they found that s-IgA levels also increased significantly and stayed elevated for about 5 hours, before they gradually returned to baseline levels.

Some of the effect is due to the fact that feelings induced by compassion and kindness are opposite to those of stress, insofar as they generate many opposite psychological and physiological effects. I describe this more fully in my books, The Five Side Effects of Kindness and The Little Book of Kindness.

As we replace stress with kindness, we take some of the pressure off of the immune system, allowing it to operate more efficiently. But these positive feelings themselves may be having direct physical effects.

In a study of over 700 patients attending their doctor for symptoms of the common cold, those given an ‘empathy enhanced visit’, where the doctor spent more time listening to the patient, such that the patient scored the doctor 10/10 on a CARE questionnaire afterwards (Compassion and Relational Empathy), recovered almost 50% faster than those who received a ‘normal’ consultation, and their immune response to the cold was also significantly higher. This has been interpreted as the positive feelings the doctor induced in the patients then impacting their immune systems.

But scientists have been exploring the link between the mind and the immune system in more direct ways. People visualising increasing levels of s-IgA were found to be able to increase them quite substantially.

The visualisation involved spending 5 minutes relaxing before spending 5 minutes imagining s-IgA levels increasing, before doing another 5 minutes of relaxation. Critics suggested that the increased levels of s-IgA were not due to visualisation, but due to relaxation simply taking pressure off the immune system, as I described above. 

A repeat of the experiment then compared people relaxing for the full 15 minutes with people doing the 5 minute section of visualisation embedded within the relaxation session. Levels of s-IgA increased in both groups over the first week, but then those who did the immune system visualisation started to increase their s-IgA levels at a faster rate than those only doing relaxation. At the end of 3 weeks, those who visualised their immune systems had increased their s-IgA levels significantly more than those only doing relaxation, demonstrating that while relaxation can improve s-IgA levels, visualisation is doing something differently and impacting the immune system in a different way.

There is a growing body of evidence that shows that in many different ways, the brain (and body) doesn’t distinguish real from imaginary. When comparing making simple finger movements with imagined movements, scans show brain changes in the same regions and to the same extent in those who do the real movements and those who do the imagined movements. As far as the brain was concerned, real and imagined movements were the same thing.

This has now been extensively tested in mechanics and sports, where similar gains in strength have been shown when people lift real objects compared with imagining lifting them. Studies even show athletes can recover faster from injury when they visualise attending the gym while they are in recovery. When returning to training after the injury period, they have lost less muscle strength than those not visualising and so are better able to ‘hit the ground running’, so to speak.

Studies with stroke patients show something similar. In several studies, patients received physiotherapy for several weeks, but half were taught to imagine making repetitive movements that they are familiar with after the physio sessions, while the other half did relaxation sessions for the same duration. Those who did visualisations recovered more and faster than those who didn’t visualise.

Studies on eating have even suggested that imagining eating activates part of the brain that senses when a person has eaten enough and so supresses appetite for more.

Studies have extended the idea of imagining the immune system to patients with cancer. In a randomised controlled trial (RCT) published in the journal, Breast, scientists invited women receiving treatment for newly diagnosed large or locally advanced breast cancer (chemotherapy, surgery, radiotherapy, and hormone treatment), to use visualisation as well.

Half of the women visualised their immune systems destroying cancer cells while the other half didn’t. The women were shown cartoons depicting the process but were also encouraged to make up their own images. They rated the clarity of their visualisations on a 1-10 scale. Blood samples were taken 10 times over 37 weeks and several immune substances were analysed.

In the women who visualised, immune activity was elevated compared with the women who didn’t visualise. Specifically, T-cells, activated T-cells, and LAK cells (lymphokine activated killer cells) were higher in the blood of those who visualised. In addition, the women who reported the highest visualisation clarity had much higher levels of NK (natural killer cells) activity during, after treatment, and again at follow up. The researchers noted that, “Guided imagery beneficially altered putative anticancer host defences during and after multimodality therapy.”

This pattern of observing elevated immune system activity when visualisation has been used in addition to cancer treatment has been shown in three other studies. 

To be clear, visualisation was not used instead of medical treatment, but in addition to it. Visualisation is something that we practice in addition to treatment, not instead of it, just like we don’t meditate instead of sleeping, but in addition to sleeping, and the meditation tends to enhance our sleep. Similarly, in these cancer studies, visualisation seemed to be enhancing the effect of the treatment by supporting the activity of the immune system.

It may well be that visualisation can be used to positively impact a larger number of conditions, especially if we target the immune system with our visualisations. But visualisation can target other systems too. In a study of total knee replacement, visualisation of healing speeded up the healing for some patients. Similarly, asthmatics have gained benefit from imagining reduced bronchospasm and inflammation, and women with interstitial cystitis experienced reduced pain when they visualised healing the bladder, relaxing the pelvic floor muscles, and quietening the nerves.

There is no question that the mind impacts the body. Research now clearly shows that the mind can impact the immune system, in ways that increase activity and in ways that decrease activity. With more research and practice, it may be that we can learn techniques that can help us to maintain our health much better by optimising our immune systems, or develop techniques for selectively targeting different systems of the body for speeding recovery from injury, illness and disease.


All references can be found in ‘How Your Mind Can Heal Your Body’, by David R Hamilton PhD (Available on Amazon in all countries)

Posted in


  1. Lesley Saunders on July 28, 2020 at 11:26 am

    Very interesting study. It is a real shame that more people do not take this up and believe in it. more. It can seem like its too good to be true but it is not

  2. Jenny on July 30, 2020 at 7:19 pm

    Hi David, I have an autoimmune disease (psoriasis) indicating that my immune system overreacts in some way and causes red and flaky patches to appear all over my body. In this era of Covid, being prone to having an inflammatory response like this is associated with worse outcomes in the case of Covid 19 infection. So I would like to use visualisation to REDUCE my body’s immune response and make it more balanced. I’m not quite sure how to visualise that, other than to think of my immune system as responding in a healthy way, neither too much or too little. Any suggestions?

    • David R. Hamilton PhD on August 4, 2020 at 12:19 pm

      Hi Jenny, with autoimmune visualisations, the idea is to imagine changing the behaviour of the immune system. Typically it is overreactive, so we then visualise it becoming calm and making friends with the skin cells (in your case). You might imagine your immune cells as animated characters, for example, and see them making friends – shaking hands, hugging, enjoying friendly conversation – with your skin cells, and all becoming calm and enjoying the new kind of interaction. I hope that helps. 🙂

      • Jenny Perkins on August 4, 2020 at 7:40 pm

        Thanks David. That’s helpful. I’ll give it a go! Best wishes, Jenny

  3. Natasja on July 31, 2020 at 7:28 am

    Thank you for this thought-provoking article. I find the placebo effect especially interesting and wondered if any studies have been performed, or noted in the two placebo studies you mentioned in the article, as to what happened when the patients were told that they had in fact not been taking apomorphine or the immunosuppressant drug? Did they understand the power of belief and chose to stop taking the drugs because they could see that they, in fact, don’t need it? Or did they feel “cheated” and had to continue taking the drugs?

    • David R. Hamilton PhD on August 4, 2020 at 12:15 pm

      Hi Natasja, The studies didn’t report on what happened afterwards. I find that, if communicated in the right way, people can feel empowered that their own mind was able to generate such powerful effects. 🙂

  4. Sue Creaton on July 31, 2020 at 8:41 am

    Thank you for posting this. I really like your video of the visualisation . I have sent it to two of my friends.

    • David R. Hamilton PhD on August 4, 2020 at 12:14 pm

      That’s nice to hear, Sue, thanks. I hope your friends find the video helpful. 🙂

Leave a Comment