New research finds links between personality traits and the expression of genes that control the activity of our immune systems.
The results of the new study don’t support a common theory that tendencies toward negative emotions such as depression or anxiety can lead to poor health—so-called “disease-prone personality.”
The researchers did find that differences in immune cell gene expression are related to a person’s degree of extraversion and conscientiousness, however.
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.
The researchers recruited a group of 121 ethnically diverse and healthy adults, 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 that measures five major dimensions of personality—extraversion, neuroticism, openness, agreeableness, and conscientiousness. Blood samples were collected from each volunteer for gene expression analysis and their typical smoking, drinking, and exercise behaviors were also recorded for control purposes. Gene expression analysis was carried out at the Social Genomics Core Laboratory at University of California, Los Angeles.
Extraverts and infection risk
“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,” says study leader Professor Kavita Vedhara of the University of Nottingham’s School of Medicine.
“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?”
Other personality traits
These two clear associations were independent of the recorded health behaviors 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 among personality, physical health, and human longevity.
The study is now available online in Psychoneuroendocrinology.
Source: University of Nottingham