A team of health psychologists at The University of Nottingham and the University of California in Los Angeles carried out a study to examine the relationship between certain personality traits and the expression of genes that can affect our health by controlling the activity of our immune systems.
The study did not find any results to support a common theory that tendencies toward negative emotions such as depression or anxiety can lead to poor health (disease-prone personality). What was related to differences in immune cell gene expression were a person's degree of extraversion and conscientiousness.
The study used highly sensitive microarray technology to examine relationships between the five major human personality traits and two groups of genes active in human white blood cells (leukocytes): one involving inflammation, and another involving antiviral responses and antibodies.
A group of 121 ethnically diverse and healthy adults were recruited. These were comprised of 86 females and 35 males with an average age of 24 (range 18-59) and an average body mass index of 23. The participants completed a personality test which measures five major dimensions of personality -- extraversion, neuroticism, openness, agreeableness and conscientiousness -- (NEO-FFI McCrae and Costa, 2004). Blood samples were collected from each volunteer for gene expression analysis and their typical smoking, drinking and exercise behaviours were also recorded for control purposes. Gene expression analysis was carried out at the Social Genomics Core Laboratory at UCLA.
Type D personality, first defined in the '90s, is characterized by feelings of negativity, depression, anxiety, stress, anger, and loneliness. The link between Type D personality and poor health outcomes is most likely driven by its hallmark high stress levels.
Conscientious people are hardworking, reliable, dutiful and able to control their impulses. They like things to be planned and like to achieve their goals.
The researchers found that being a conscientious person can protect against the onset of disease.
Researchers found a one unit increase on the 1 - 4 scale for conscientiousness decreases the odds of a stroke diagnosis by 37 percent.
It also decreases the odds of a high blood pressure diagnosis by 27 percent, arthritis by 23 percent and diabetes by 20 percent.
One of the researchers, Professor Joshua Jackson, told MailOnline they did not differentiate between type 1 and type 2 diabetes, but added: 'Because it was a new diagnosis of diabetes, and everyone is an older adult, I would guess that most were type 2.'
Type 1 diabetes is caused when the body's immune system incorrectly targets and kill the cells in the pancreas that are responsible for producing insulin.
Type 2 diabetes is when the body becomes less able to respond to insulin. It is usually diagnosed in over 30 year-olds and is often associated with excess body weight.
The link between conscientiousness and health could be because people who are conscientious are likely to carry out healthy behaviours like healthy eating and exercise, which are important for preventing diseases like stroke, high blood pressure and diabetes, researchers said.
Open people are curious, imaginative, like playing with new ideas, and have a broad range of interests.
A one unit increase on the 1 - 4 scale for openness decreased the odds of a stroke diagnosis by 31 percent, heart conditions by 17 percent, high blood pressure by 29 percent, and arthritis by 21 percent.
Being more open might help a person be more creative in relieving stress and may improve their health through better communication with physicians.
Extroverted people are positive, assertive, talkative, social and like to be the life and soul of a party.
Researchers found a one unit increase in extroversion decreased only the odds of a high blood pressure diagnosis by 26 percent.
Agreeable individuals value getting along with other people. They tend to be considerate, kind, generous, helpful, trusting and trustworthy, and willing to compromise.
A one unit increase in agreeableness decreased the odds of an arthritis diagnosis by 21 percent.
Professor Joshua Jackson, told MailOnline previous studies have not linked the trait of agreeableness to health, so he would want to replicate these findings in future studies to be sure of the link.
One theory, however, is that the social connections well-fostered by agreeable people protect them against disease.
He said: 'Agreeable individuals are warm, caring. They make deeper connections. Social connections are associated with good health, there's lots of research on that. That could be the reason why agreeableness is protective.
Neurotic people are sensitive and nervous, and often experience anger, anxiety, or depression.
Neurotic people who are constantly worrying are more likely to develop a disease to worry about in later life, the study found.
A one unit increase in neuroticism increased the odds of being diagnosed with a heart condition by 24 percent, lung disease by 29 percent, high blood pressure by 37 percent, and arthritis by 25 percent.
According to Traditional Chinese Medicine (TCM), when certain organs are weak, deficient or diseased, a certain type of emotion may come to the surface. Here are the five main organs and their associated emotions in TCM theory:
Anger: The liver is associated with anger and symptoms displayed in the eyes (darkness around the eyes) and blood vessel pathologies (ex. varicose veins) are common.
Worry: The spleen is associated with worry. In TCM, the spleen governs digestion along with the stomach. When the spleen is weak, symptoms of indigestion, bloating, diarrhea, undigested food, and irritable bowel syndrome occur.
Sadness/Grief: The lungs are associated with sadness and grief. In TCM, the lungs control the immune system, skin, and of course, breathing. Many chronic diseases stem from unresolved grief. We could even hypothesize, according to TCM theory, that given that cancer is a failure of the body’s immune system to detect and eliminate a tumor, perhaps there is a connection to grief.
Fear: The kidneys are associated with fear. In TCM, the kidneys govern bones, the nervous system, the lower back and the genitourinary system (kidney, bladder).
Joy: According to TCM, the heart is associated with joy. Though this is normally a good thing and most of us would like to have more joy in our life, the concept is best described as “excessive joy” or overexcitement. For example, when your heart is overactive in TCM, you may suffer from insomnia.
Leading research, Professor Kavita Vedhara, from The University of Nottingham's School of Medicine, said: “Our results indicated that 'extraversion' was significantly associated with an increased expression of pro-inflammatory genes and that 'conscientiousness' was linked to a reduced expression of pro-inflammatory genes. In other words, individuals who we would expect to be exposed to more infections as a result of their socially orientated nature (i.e., extraverts) appear to have immune systems that we would expect can deal effectively with infection. While individuals who may be less exposed to infections because of their cautious/conscientious dispositions have immune systems that may respond less well. We can't, however, say which came first. Is this our biology determining our psychology or our psychology determining our biology?"
These two clear associations were independent of the recorded health behaviours of the participants and subsets of white blood cells which are the cells of the body's immune system. They were also independent of the amount of negative emotions people experienced. The study also found that expression of antiviral/antibody-related genes was not significantly associated with any personality dimension.
In the remaining three categories of personality, 'openness' also trended towards a reduced expression of pro-inflammatory genes and 'neuroticism' and 'agreeableness' remained unassociated with gene expression.
The research concludes that although the biological mechanisms of these associations need to be explored in future research, these new data may shed new light on the long-observed epidemiological associations between personality, physical health, and human longevity.
April McCarthy is a community journalist playing an active role reporting and analyzing world events to advance our health and eco-friendly initiatives.