How Stress Causes Illness: Psycho Neuro Immunology

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

What is Psycho neuro immunology? 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 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

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 establishes a scientifically accepted linkage between state of mind, emotions and physical health.

This 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.

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.


  • What are some of your recurring mental and emotional patterns, both healthy and unhealthy? When did you first learn them?                                                                 
  • What are your ‘feel-good’ strategies that make you feel better? How well do you balance the stress in your life with calm and tranquility?

Now it’s time to focus on your mental well-being, emotional well-being, relational well-being and spiritual well-being along with your physical well-being. Read our blogs on: Physical, Mental, Emotional, Spiritual and Relational stressors.


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