What do we measure?
The modern study of the mind-body connection is called by many names—psychoneuroimmunology, psychophysiology, neuropsychology…basically they all mean how thoughts and feelings affect the nervous system and then the body.  One way to explore this interaction is by measuring the affects of stress.   Some common measurements include cortisol (stress hormone) levels, immune function, wound healing, and cardiovascular reactivity, meaning how quickly and how high someone’s blood pressure and heart rate respond to stress.  Many studies have shown how stress negatively impacts all of the above and more.  Chronic caregivers have significantly decreased immune function, and widows can take up to a year to restore immunity after the death of a spouse.  Victims of sexual abuse and people with posttraumatic stress disorder show increased cardiovascular reactivity and abnormalities of cortisol function. Dental students took three days longer to heal a 3.5 mm biopsy of their upper palates done just before finals, versus a symmetrical one done during the previous summer vacation.  And if a 3.5 mm lesion takes 3 days longer to heal in the face of exam stress, consider the implications when compared to the healing required for a very anxious patient facing major surgery with the possibility of cancer. 

On the other hand, simply playing bridge with friends for a few hours can measurably improve immune function, and hearty laughter can enhance immunity for twelve hours afterwards.  Exercise decreases cardiovascular reactivity.  Massage and listening to music decrease cortisol levels. In general, stress, bereavement, chronic care giving, loneliness, anger, trauma and difficult marital relationships negatively impact, in a measurable way, how our bodies function.  However, research has verified we can positively affect our health with love, friendship, laughter, spirituality, a positive outlook, meditation, yoga, exercise, massage, music, the creative arts, journaling, being in nature, and having pets.

Neurotransmitters
Neurotransmitters send signals throughout the nervous system.  We used to think these chemicals, such as dopamine and serotonin, resided in the brain at the end of nerve cells.  We now know that they can be found in many other organs--the heart, the gut, the immune system--and that they can diffuse out into the tissues and the blood.  This is why so much of what happens to us shows up in many different parts of the body; why depression, associated with low serotonin levels in the brain, also causes decreased immune function and decreased bowel function, and why anti-depressants can have gastrointestinal side effects.  Why do we have a “gut feeling” about something?  Because the neurotransmitters in our gut can be a mirror reflection of what’s going on in our head.  Every day more neurotransmitters, cytokines, lymphokines, peptides and hormones and their interrelationships are being discovered, as well as how these factors are affected by events in our lives, and how we choose to respond to those events.

Immune system
We used to view the immune system as a passive force, waiting around to ward off enemy bacteria.  We now know it is integral to every function of our bodies.  Natural killer cells, one type of immune cell, are responsible for cleaning up pre-cancerous cells in our bodies.  Inflammatory cells modulate the scarring reactions of surgery and endometriosis, as well as the process of coronary artery disease, and the symptoms of autoimmune disease such as rheumatoid arthritis.  Immune cells even have estrogen receptors, which is one possible explanation for why women have more autoimmune disorders than men. Not only do immune cells have receptors (docking stations for chemical messengers that change the shape and function of a cell) for all of these neurotransmitters, hormones, etc., they actually manufacture their own neurotransmitters, peptides and modulators in a constant biochemical local feedback interaction.    Two of the most important mind-body findings about immune cells are:

1)  cortisol receptors on immune cells are how stress affects the immune system, and
2)  neurotransmitter receptors on immune cells are how mood affects the immune system.

Therefore, what we do or don’t do to positively impact stress and mood can have far reaching effects on our health. 

Can we influence our physiology?
The autonomic nervous system, in charge of constant functions like heart rate and breathing, was named autonomic because it was thought to carry on independently in the background of our lives.  However, ever since Dr. Benson’s discovery of the “relaxation response”, in which quiet breathing was found to be able to lower blood pressure, we have uncovered ever-increasing evidence that we can to some extent impact our own physiology.  Over one hundred studies have verified that relaxation can lower blood pressure.  Biofeedback studies have demonstrated the ability to raise or lower the temperature of one finger, or raise the temperature of one small square of skin on the back by imagining a candle flame at that spot.  Diabetics have been able to increase by several degrees the temperature of their feet, thereby increasing extremity blood flow, so important in counteracting the blood vessel complications of this disorder.

How is this possible?
Looking at brain connections in a basic way, if you are right handed, then the left side of your brain is more involved with linear thinking, math and logic.  The right side is more associated with creativity, pictures and relationships between objects.  This right brain has very dense connections to the limbic system and amygdala, parts of the brain that are involved with emotion and five sense memories.  The smell of wood smoke on a fall day, or of a pie baking; hearing the sounds of the ocean or the wind in the trees; the feel of an old sweater or a baseball glove, all can trigger memories of another time, and the emotions that went with them.  These limbic system memories and emotions are in turn densely connected to the hypothalamus, the main switchboard of brain function.  On one track, the hypothalamus interacts with the autonomic nervous system, where pleasant memories are translated into decreased heart rate, blood pressure, respiration and relaxed muscle tone.  On yet another track, the hypothalamus sends signals to the pituitary gland, which controls many bodily hormones and functions.  These memories are here translated into a decrease in cortisol, the stress hormone, and normalization of sex hormones and blood sugar levels.  In turn all of these hormones and output from the autonomic nervous system feed back into the immune system, making immune cells function at their optimum.  In short, sensory images provide immediate access to the right brain, and begin the psychoneurophysiology cascade, translating that image into feelings and then into bodily changes. 

This happens constantly and spontaneously in our daily lives, but we can also have conscious input.  From pre-operative patients who can imagine decreased pain and improved bowel function and have it happen, to yoga masters who can skewer themselves with metal rods and feel no pain and have no bleeding, we are only at the beginning of our understanding of the magnificence and intricacy of the mind-body connection.

See the next section for how we can utilize these images to improve our health.