How Stress Causes Illness: PsychoNeuroImmunology

how stress causes immunity

Do you know how stress causes illness? The immune system serves two critical functions, viz. protection and repair. And there is clinching proof to that stress, immunity and illness are closely and directly linked. This premise is scientifically supported by the emerging and exciting field of psychoneuroimmunology (PNI).

More than 70% of all routine hospital visits can be attributed to ‘stress’. I came across these statistics during my medical education. None of my text books taught me how. But it made common sense. Having had psoriasis for almost 20 years, I know that my symptoms flare up when I am unhappy. In my work in the post-operative wards, I made the observation that cheerful patients seemed to recover sooner, and with fewer complications.

In my mind, stress and illness are undoubtedly inter-related.The emerging science of Psychoneuroimmunology explains how. Finally, I just wonder if they couldn’t have come up with a shorter name!

What is Psychoneuroimmunology? How stress causes illness exactly

explore how stress causes illness
Stress is a ticking time bomb

Dr. Kenneth Pelletier defines PNI as “the study of the intricate interaction of consciousness (psycho), brain and central nervous system (neuro), and the body’s defense against external infection and internal aberrant cell division (immunology).”

Simply put, this emerging science states that mind (where we experience stress) and body (where we have most illnesses) are interlinked. So when we are under stress, our immunity drops. That’s how stress stress causes illness.


“The body isn’t there simply to carry the head.” – Dr. Candace Pert

Dr. Candace Pert, her sense of humour aside, is better known for her book Molecules of Emotion. Through her work she shows how the bio-chemicals in our bodies form a dynamic information network, linking mind and body. She establishes a biomolecular basis for our emotions and empowers us to understand ourselves, our feelings, and the connection between our minds and our bodies – or bodyminds.

Why Psycho-neuro-immunology is exciting for cancer

Conventional medicine treats illnesses like cancer as uncontrolled growth of cells and deals with it only as a disease of the body. People who have survived cancer know that ‘mental strength’ is key.

PNI [why didn’t I shorten it before?] establishes a scientifically accepted linkage between state of mind / emotions and physical health. This means that medical professionals will begin to pay more attention to the mental well-being of cancer patients.

This also means that we will begin to include more holistic and integrated therapies not only for understanding how stress causes illness but also creating a recovery plan.

Especially in India where the government recognises multiple healing systems under the AYUSH initiativeAyurveda, Yoga, Unani, Siddha and Homeopathy – we will begin to see an increasing usage of alternate systems to complement or replace mainstream treatments. All these systems already teach the mind-body connection, and have done so for centuries.

Hmmm…new science, or old?

Ancient wellness traditions have understood the mind-body interaction for centuries and have incorporated it into their approach and therapies. In India for example, the Yogic philosophy teaches that the body, breath, emotion and mind are inextricably linked. The Chinese system of Tai Chi has also taught this principle for centuries. I guess it was just a matter of time that science caught up!

I know about PNI. Now what?

Now it’s time to focus on your mental well-being as well as your physical. When you take your next round of medication, remember that a dose of de-stress is just as important. If you need support, try to find a local support group in your city. Support groups have been proven to improve cancer survival.

And, of course, stay tuned to Cancer Awakens. We will keep bringing you more information and tips that may make your cancer journey easier.


  • What are some of your recurring mental and emotional patterns, both healthy and unhealthy? When did you first learn them?
  • While mainstream treatments deal with the physical aspects of cancer, how do you deal with your thoughts and feelings?                                                                    
  • What are your ‘feel-good’ strategies that make you feel better? How well do you balance the stress in your life with calm and tranquillity?

If you have observed (or intuitively felt) the connection between your emotional state and your physical health, please share your experiences below. While the science is undoubtedly important, the personal anecdotes are equally so!


  1. My mother-in-law was diagnosed with uterine cancer in May 2008 and since it was at an early stage, they just removed her uterus. The doctor suggested radiation therapy for some 28 sessions and after her last session (which was internal raditiation – don’t know the medical term), she developed a condition (Deep Vein Thrombosis) due to which she now has to live with swollen legs and numb toes. She used to be a very active person – Iyenger trained yoga student, artist, avid reader and a very spiritual person.

    She is not able to pursue a lot of yoga, art or reading anymore ’cause of fatigue and ongoing health issues. However, she is determined to continue living her life and wakes up with a smile on her face only because of her mental strength and positive attitude in life. I will be sure to recommend this site to her. Thanks for such great work.

  2. Interesting initiative, and to be commended. I am a clinical psychologist with a mind-body specialization…and yes, psychoneuroimmunology has established the “science” behind the mind body connection. It will take much longer for medical schools to integrate this into curriculum, training, and practice of physicians.

    For the person out there, it’s important to take some control of your healing, and preemptively, on your stress. Stress is a response! We can change this response, and that is where the gold lies right now: helping people understand how to change their responses to stress. Regular meditation, breath work and or yoga are invaluable for balancing out the impact of daily life.

    Additionally, look at the WHY of stress. One way to do this is to look at the situations that lead to a stressful response, and evaluate your response. What aspect of the situation caused you to respond with stress?

    Breaking your stress response down into chunks….and then looking at each…and managing each…can help you devise newer ways of responding.
    This is equally applicable to huge overwhelming life situations (loss of job, death of spouse, ) as it is to daily life situations…

    For example…if a person who matters to you (spouse, boss, in-law) speaks to you in a way that elicits a stress response…take three deep breaths…this kicks in the parasympathetic nervous system, to balance out the immediate arousal of the body…increased heartbeat, body tension, worrisome thoughts (oh no, now what.. and worse!:)),

    and after taking in these deep breaths, stop to question the conclusions you have reached automatically about this situation. We jump to conclusions that are usually based on anxiety and worry, rather than rational thinking. What if the person is just like that every morning? What if they have something that is worrying them? What if they are indeed upset with you over something, but it can be resolved?

    The important thing is to “disrupt” your usual stress response…weaken it…and build up alternative coping responses.

    Managing overwhelming illness is also hugely helped with these mind-body techniques. More on those in another post:).

    Hope this post is helpful to someone out there:).

    • Dear Kumkum, thank you for dropping by and taking the time to respond with, what I believe to be, a great addition to our article. After reading your comment I was inspired to visit your website and I see that there are many parallels in our work.

      I would like to extend an invitation to you contribute to Cancer Awakens as a guest author, to share your experience and insight to help those touched by cancer. Does this interest you?

      Dr. Santhan


Please enter your comment!
Please enter your name here