Psychoneuroimmunology (PNI) is the study of the link between emotion, immunity and the brain. Research over the last decade has offered some surprising insights. Positive emotion has in the past been linked with good health, while negative emotions were thought to lead to illness but studies are proving that even though this is sometimes correct, there are often cases where it isn’t.
It has been found that stress can actually boost the immune system, making it stronger while optimism could be draining it. Health seems to improve in individuals where success and self-esteem are in harmony. The link between emotion and immunity is complex yet filled with exciting surprises for doctors, scientists and psychologists.
Healthy Stress and Immunity
The fact that stress has been linked to increased blood pressure, the risk of heart disease, a suppressed immune system and even the flu has been proved over and over again in studies.
Scientists now also have proof that even though chronic stress has a harmful effect on the immune system; short- term stress actually seems to boost it. The human body is actually primed to respond to threatening situations and can deal with them.
To prove this, a study was conducted on rats at the University of Colorado. Scientists exposed all the rats to bacterial infection, while some were also exposed to stress by receiving electric shocks to their tails. The rats, who received the shock at the time of infection, resisted the infection and remained healthier than the rats not given the shock.
The scientists concluded that patients with infections might be better off if they are not given anti-anxiety drugs-often doctors need to calm distressed patients-as these drugs may suppress the immune systems response to helping the patient recover.
How many friends?
Close friendships with a few friends does seems to offer less immunity, whereas individuals who choose to have a wider social circle have increased immunity. A study conducted on freshmen at Carnegie Mellon, proved this when the scientists gave the new students the flu vaccine. Those with a larger social network proved to be more immune to the flu than those who had smaller groups of friends. The loneliest of the students had the least antibodies and therefore, the lowest immunity.
This proved a clear distinction between loneliness and the size of the social network. Lonely students had lowered immune response to one component, whereas those who had a few friends had it on another component. It seems that optimal immunity comes with having a wide circle of friends and the researchers observed that older, better-connected students visited the infirmary less often than the freshmen.
Harmony between self-esteem and success
A lack of confidence or self-esteem, combined with extreme success may threaten immunity in some people. When achievement doesn’t meet expectations there is a marked lowering of the immune system.
The phenomenon of a self-image that differs from what a person can actually achieve, wishes to achieve and actually does achieve is called “self-discrepancy” by psychologists. Blood tests, taken by researchers conducting a study on students at Duke University, showed that those with fewer discrepancies had a greater T cell count. When adequate progress was made by the group with their own self-evaluation their immunity improved, unlike those not making any progress, or those progressing too fast. Those that had both high self-esteem and success had the highest immunity.
The research showed that continual evaluation and modification of behavior in order to reach a goal decreases immunity – a disruption in the phenomenon known as “self-regulation”. If the initial efforts to reach the goal fail, there will be a drop in mood, but motivation may rise. However, if the failure continues, then the motivation ceases altogether. The higher the self-esteem at the outset, the further the mood and motivation will fall.
The Curiosity Boost
Optimism and good health always go together, but according to studies a dose of reality is also needed otherwise it won’t always work. Research conducted on 1,041 patients at Harvard; found that those who were optimistic in a realistic way (hopeful) were less likely to develop diabetes, high blood pressure and flu than those who were complete optimists, believing that they could overcome everything.
The participants who were most curious and skeptical and kept seeking information from their doctors or the Internet also had a better immunity.
By pushing too hard some optimists seem to be stressing their immune systems and are making themselves ill. In a study conducted by researchers at the University of Kentucky, optimists were given a stressful mathematics test and it was found that their levels of immunity dropped. The study suggests that it may be more difficult on the immune system to persist on a problem rather than to give up.
Type A individuals are those who are anxious, impatient and hostile and for years it was believed that they were the most likely to have heart attacks and other health problems. Type B personalities have calmer, happier natures. Psychologists have now identified another type of personality that they have labeled as a Type D. These people are cynical and hostile, but are also unexpressive and keep bad feelings pent up inside them.
Psychologists, cardiologists and immunologists investigated the possible connection between Type D traits in male heart disease patients in Belgium for a number of years. The patients who had Type D personalities were far more likely to have heart attacks, more specifically coronary heart failure. The Type D patients were four times more likely to die of heart disease.
The explanation for this was that all the Type D heart patients had raised tumor necrosis factor (TNF-alpha), an inflammatory molecule produced by immune cells. TNF-alpha causes quite a few destructive actions, and one of those is that it ruptures arterial plaque, which then obstructs the artery or vain. This causes the thrombosis which then results in a heart attack.
This field of research has also found that Type D personalities have killer T cells that are less active, resulting in a diminished ability to fight infection. This is the opposite to what is found in more expressive types of people. Studies have also shown that social inhibition is linked to less action of the immune system toward infectious diseases.
The link between emotion and health is an area that is been thoroughly researched. The role of stress and the double-sided sword of optimism, how emotional states influence the heart, the aging process and how disease is fought are all areas of great interest. The science of psychoneuroimmunology is a relatively new field of study, but is looking hard at providing the answers.
Stress and infection
Animal studies, conducted by a psychologist and immunologist at the Ohio State University, in the early 1980s, had shown a link between stresses and infection. They continued their research on medical students and found that the students had lowered immunity over the three day exam period every year. The students had fewer killer T cells to fight off tumors and viral infections. They also had a lower production of immunity-boosting gamma interferon.
These pioneering early studies and their findings intrigued researchers and opened the floodgates for them to conduct more studies. In 2004, Suzanne Segerstom, PhD, of the University of Kentucky, and Gregory Miller, PhD, Of the University of British Colombia, did a meta-analysis of 300 studies on stress and health. They found some intriguing patterns. People who were stressed out for a few minutes during a lab experiment had a burst of one type of “first responder” activity, mixed with other signs of weakening. If the stress continued for a longer period- anything between a few days to a few years, as we see in real life situations, the immunity tumbled even further. Therefore, chronic stress weakens the immune system.
The meta-analysis also showed that the elderly and those who are already sick are more vulnerable to stress-related immune changes. Older people’s immune systems become more vulnerable when they suffer from chronic, mild depression. The participants who proved to be most vulnerable were those who were over the age of 70 and were caring for someone with Alzheimer’s disease. They had weaker lymphocyte-T cell responses to two mitogens, which assist the body’s response to viruses and bacteria. The immune response had still not returned to normal eighteen months later and immunity continued to decline as the participants aged. The duration of the depression is what was shown to take its toll on the immune system rather than the severity of the depression. Depression together with old age takes an even bigger toll on the immune system.
The researchers also noted that a lack of social support is a risk factor for depression- as was proven by the research team at Carnegie Mellon University mentioned earlier with their research on freshmen. Social isolation and feelings of loneliness weakened their immune system.