Did you know that your mental state can affect your immune system? The wave of research that points to a circuit linking the immune system and brain connects illness, stress, mood and thought in a whole new way. It’s known as Psychoneuroimmunology (PNI). As Mental Health Wellness Week draws to a close, we look at this new science that examines the cross-talk between body and mind.class="intro">
To understand the connection between thoughts and physiology, we first need to understand the important role played by the immune system. We know already that the immune system is key to fighting infectious diseases and inflammatory or autoimmune diseases, like rheumatoid arthritis, cancerous tumors and so on. But how is the immune system affected by the brain?
Medicine shows us that when we’re stressed or experience certain emotions we register this in the brain. Scans reveal that the brain is activated by stress and certain emotions, such as anger or fear. In fact, the scans even show that the patterns of activation differ when you’re, say, angry to when you’re afraid. “The brain is our conduit for affecting the body in response to different emotional triggers and to different thoughts,” says Dr Margaret Kemeny, professor of psychiatry at the University of California, San Francisco (UCSF).
Dr Kemeny explains how the brain releases substances into the body, including stress hormones (cortisole) when we are stressed. “These hormones can affect the immune system in two ways. First, they affect the distribution of immune or white blood cells, which is important as immune cells needs to be in the right place at the right time if they are to protect the body from disease. Secondly, stress hormones can also influence the functioning of the immune cells – in other words, they can alter the way these cells are able to act when, for example, they need to kill bacteria. Stress hormones are therefore very powerful and can even function as an immunosuppressant.”
Medicine teaches us that the body is built to respond to stress and we were built for our brains, through nerve fibres, to be able to communicate to our immune systems. The neural pathways between our brains and immune organs are part of our biological hardwiring. But what does this have to do with stress?
In the 1950s, János Hugo Bruno “Hans” Selye, a pioneering Austrian-Canadian endocrinologist, demonstrated that stress triggers the release of hormones or cortisoles and this causes an alteration in the immune system in that it suppresses the immunity. In the mid 80s, there was a resurgence in interest in the effects of stress on the immune system. In studies conducted on medical students at exam time, Professor Janice Kiecolt-Glaser, the Director of the Ohio State Institute for Behavioral Medicine Research, concluded that stress suppresses, among other things, the function of the body’s natural killer cells (those responsible, for instance, in fighting tumors) and also reactivates latent viruses, like, for example, the herpes simplex virus, causing them to replicate themselves. It has also been proven that chronic stress can reduce the effectiveness of vaccines and can also delay wound healing time and tissue repair.
But what about thoughts? One need only consider the so-called “placebo effect” – where one’s belief that one is getting health-improving drugs actually makes one physically better – to see the effect of the mind on the body. But studies also show that our social worlds affect our health. Research has shown that a positive social support system predicts better health, better functioning of the hormonal and immune systems and even a longer life. Conversely, negative experiences such as loss or bereavement have negative consequences for hormones, the immune system and health. Even loss of social status and its concurrent feelings of subordination, mistreatment and defeat, has been shown to significantly affect the immune system. New research also indicates that stress hormones can influence cancer-cell growth.
So what do we know? We know, then, that the hardware linking the brain to the immune system is there. We know that stress can affect the immune system and that thoughts and feelings seem to be key. So what about interventions? If we reduce our stress levels, will our immune system be healthier and will we have reduced disease? Can interventions that change the way we think and feel improve our immune functioning?
“Yes,” says Dr Kemeny. “There is suggestive evidence that therapeutic interventions such as social support groups, problem solving groups, diary writing, cognitive therapy, mindfulness based reflection, hypnosis and so on, can boost the immune system.”
Kemeny refers to research done by Dr David Spiegel of the Department of Psychiatry and Behavioral Sciences at Stanford University Medical Center that showed that support group intervention was associated with reduced mortality in women with metastatic breast cancer. She says, “While we’re still a long way from being able to write prescriptions for interventions to support immune health, it is clear that understanding the connection between the immune system and our minds is essential for living a life of wellness.”