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The Brain-Body Connection

Everything old is new again in psychoneuroimmunology


Have you heard the word psychoneuroimmunology? It’s a fascinating branch of research looking at our gut-brain connection and how it keeps us healthy. Pack it up into your personal lexicon; you’ll be a hit at your next fun-filled gathering!

From as far back as we know—and probably farther—our human system has perplexed and intrigued the deepest thinkers. Extraordinary theories abound in historical records about how our bodies and minds work and how other forces influence our behaviour, our health, and our lives.

Hippocrates and his contemporaries believed that four key bodily fluids, including blood, phlegm, and both black and yellow bile (known collectively as “humors”), were the drivers of health and disease.

Centuries later, philosopher and surgeon Galen’s position that good health involved a “balance of the passions” (anger, anxiety, grief) was grounded in those ancient tenets of humorism. It wasn’t until Descartes proposed a separation of mind and body in the 17th century that the biomedical model took hold in research and practice.

Since then, of course, we’ve made incredible strides in our understanding of anatomy, physiology, and pathology. Yet the separation of body and mind intuitively didn’t feel right for many. Now it seems that we’ve come full circle, and researchers are finding evidence that the mind-body connection is a powerful force when it comes to health.

Psycho + neuro + immunology = PNI

Simply speaking, this branch of research and medicine considers the bidirectional relationships between emotions, the activities of the nervous system, and immune function.


Gut feeling

The central nervous system (CNS) comprises the brain and the spinal cord, and it controls thought processes, registers sensations through a complex of nerve tissues, and guides movement.

The CNS sends information to the gut via the vagus nerve and other nerve pathways, as well as the immune system signalling molecules (cytokines) and other chemical messengers including hormones and neurotransmitters. Microbial changes at the gut level, however, can also affect the brain.


Gut bacteria and immune function

People often think of gut bacteria in terms of digestion or digestive problems such as irritable bowel syndrome. In the last several years, researchers have also pointed to the role of gut bacteria in supporting immune function. As much as 80 percent of immune system cells are in the intestinal tract, so it makes sense that an imbalance of bacteria can affect how your immune system functions.

Research has connected dysbiosis, or bacterial imbalance, with non-digestive chronic conditions including allergy, asthma, cardiovascular disease, metabolic syndrome, and obesity. But research is also connecting gut bacteria with emotions.

Jason Tetro, microbiologist and author of The Germ Files (Doubleday, 2016), explains that after eating, gut bacteria create byproducts of metabolism that can be recognized by immune cells in the intestines. The immune system responds based on the signal it receives. If the signal suggests there’s no cause for alarm, the immune system does nothing.

An allergen, on the other hand, causes the immune system to go into the “fight or flight” response. If the immune system is told that a pathogen or infection is present, it will trigger low-level inflammation as your body goes into high alert.


Inflammation effects

Similarly, dysbiosis can trigger low-level inflammation in the body. Low-level inflammation can affect the brain, and the brain, likewise, can influence microbial composition and function through neural and hormonal processes. Significantly, research is starting to connect bacterial dysbiosis with stress-related disorders, anxiety, and depression. In other words, the brain, the immune system, and our moods are inextricably intertwined.


Microbial diversity

Tetro recommends that we support strong diversity in the microbial population to damper negative outcomes and enhance positive ones. In terms of supporting the bacterial population, we can only work on a short-term or daily basis.

Be sure to eat a varied diet including fermented foods, and use probiotics daily. Tetro also suggests that we always take probiotics with the same first name (genus) at the same time. For example, your probiotic supplement should contain only Lactobacillus bacteria or Bifidobacteria, but not both. Bacteria from the Lactobacillus genus, the Bifidobacterium genus, and Bacillus coagulans have been shown to have benefits for humans.


For probiotic supplements, according to Tetro, adults need 5 to 10 billion active bacteria, while children need 1 to 2 billion active bacteria, daily.


Skin connections

Our emotions often show in our skin as we suddenly flush in embarrassment or turn pale when we’re frightened. It shouldn’t be surprising, then, to learn the PNI connection with skin health.

Stress is a factor in 70 percent of atopic dermatitis cases and 39 percent of psoriasis cases. Hives connect with depression, hostility, and rage. Almost one quarter of people with alopecia areata (spot baldness) report stress, as well as anxiety, depression, and paranoia. Stress management is an important component in skin healing.


Mom and baby

During pregnancy, stress and anxiety can be harmful for the mom-to-be, but those stress hormones can also cross the placenta and have an impact on junior. An expanding body during pregnancy also causes immune system changes that can affect sleep, concentration, memory, and emotions.

Stress and anxiety during pregnancy has been associated with high blood pressure, spontaneous terminations, preeclampsia, and premature labour, as well as difficult labour and delivery. Mom’s stress level during pregnancy can also be a factor in baby’s low birth weight, disordered sleeping, irritability, and difficulty acquiring language and social skills.


Turnabout is healthy play

Studies of the mind-body connection also show that positive psychological well-being is associated with improved health and longevity. Research shows that people with a more positive emotional style were less likely to succumb to upper respiratory tract infections and experienced fewer headaches and less chest pain.

Those with emotional vitality are also at reduced risk of cardiovascular disease, even after accounting for age, gender, marital status, and lifestyle habits such as smoking and alcohol consumption.

A laughing matter

Research shows that laughter may be the best medicine. A good giggle helps stimulate the organs, and a deep gasp of oxygen-rich air not only releases feel-good endorphins, but also energizes our lungs and muscles, including our heart. Laughter also helps thicken the inner lining of blood vessels, which improves blood flow. After a bout of chuckles, we also benefit from a lower stress response, which leads to relaxation.


Mind your health

Studies have linked mindfulness activities such as yoga, meditation, and focused breathing with improving a range of outcomes for people experiencing anxiety, depression, stress, chronic pain, psychological symptoms associated with cancer, and memory retrieval. Buy a mindfulness CD, take a class—or simply remember to breathe. Your health will benefit.



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