What is Psychoneuroimmunology? - Definition & Impact

Lesson Transcript
Instructor: Victoria Leo

Victoria teaches college, authors books, has a therapy practice and masters degrees in anthropology and psychology.

Psychoneuroimmunology (PNI) is the study of how the brain, nervous system, and the immune system impact each other. Applications include how stress leads to illness and how chronic inflammation can lead to cardiovascular problems and cancer.

What Is Psychoneuroimmunology?

Did your mother ever tell you to be sure to bundle up properly in the winter so you would not get sick? Well, mine did, but I never listened because I thought only germs, not being cold, could make me sick. Yet every time I shivered with an inadequate coat, I got sick. A new science is proving all those moms right.

Psychoneuroimmunology (PNI) - and its newer name psychoneuroendoimmunology (PNEI) - is an exciting subject in health today but that jaw-breaker of a name is daunting. Let's break it down, and you'll see how simple it is:

  • 'psycho-' means thoughts and emotions
  • '-neuro-' means that the physical brain is involved
  • '-endo-' brings in the endocrine system
  • '-immunology' explains how your immune system protects you from illness

PNI researchers study how your emotions and thoughts impact your brain, hormones, and nervous system and also your immune system's ability to protect you. It can also work the other way - changes in the immune and endocrine systems create changes in your nervous system which lead to changes in your emotions. Let's see how this interaction works.

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  • 0:00 What Is Psychoneuroimmunology?
  • 1:12 Why Are Researchers…
  • 2:55 How Is PNI Research…
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Why Are Researchers Excited About Studying PNI?

For a long time, the idea that your emotions could impact your physical health was considered a myth believed by people who supported holistic health in place of traditional medicine. Over the past 25 years, solid research has proven that prolonged stress and specific traumatic experiences change the biochemistry of your brain and your hormones.

Stressful emotions also reduce the numbers and effectiveness of immune system cells, including

  • The inflammation response which is part of your non-specific protection
  • The t cells that directly attack invaders and the Natural Killer (NK) t-cells that rid you of cancers
  • The macrophages that also attack directly
  • The cells and processes, including cytokines, that fuel chronic inflammation - a risk factor for cardiovascular disease and cancer

People who were abused or neglected as children can have permanent changes in their brain chemistry and immune response as a result. Trauma survivors, like military veterans, natural disaster and assault victims, and those who work in first responder roles, have higher than expected incidences of both infectious illnesses (because their immune response to viruses is reduced) and cancer.

Even loneliness can be the cause of immune system suppression that can lead to illness. PNI also studies how positive emotions can bolster both immune and endocrine system responses. The interactions work in the other direction as well, with many disease sufferers prone to developing clinical depression in response to lowered hormone levels and chronic inflammation. Studies of cancer victims and other disease-sufferers who receive psychotherapy and group support show that these interventions in emotional health can have an impact on physical health.

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