Personality traits are linked to expression of genes which control immune system activity, new research from University of Nottingham has found.

The results run counter to a common theory that tendencies toward negative emotions such as depression or anxiety can lead to poor health, the so-called Disease-prone Personality. However, researchers did observe that differences in immune cell gene expression are related to a person’s level of extraversion and conscientiousness.

In the study, highly sensitive DNA microarray technology was used to look at relationships between the five major human personality traits.

Inflammation and Personality Traits

They also examined two groups of genes active in human leukocytes (white blood cells). One group involved inflammation, and another involved antiviral responses and antibodies.

The group studied was of 121 ethnically diverse and healthy adults. There were 86 females and 35 males with an average age of 24, out of an age range of 18-59, and an average body mass index of 23.

A personality test was given that measures five major dimensions of personality:

  • Extraversion

  • Neuroticism

  • Openness

  • Agreeableness

  • Conscientiousness

From each participant, blood samples were collected for gene expression analysis. Typical smoking, drinking, and exercise behaviors were also recorded for control purposes.

Extraversion and Conscientiousness

“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,” said Professor Kavita Vedhara, study leader.

“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 obvious links were independent of the health behaviors of the participants and subsets of white blood cells which are the cells of the body’s immune system. They were also not dependent on the level of negative emotions people experienced.

Openness Genes

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 conclusion the researchers came to is that although the biological mechanisms of these associations need to be explored in future research, the new data may shed new light on the long-observed epidemiological associations among personality, physical health, and human longevity.

What is the Function of the Immune System

The immune system protects organisms from infection with layered defenses.

Physical barriers prevent pathogens such as bacteria and viruses from entering the organism. If a pathogen breaches these barriers, the innate immune system provides an immediate, but non-specific response. Innate immune systems are found in all plants and animals.

If pathogens successfully evade the innate response, vertebrates possess a second layer of protection, the adaptive immune system, which is activated by the innate response. Here, the immune system adapts its response during an infection to improve its recognition of the pathogen.

This improved response is then retained after the pathogen has been eliminated, in the form of an immunological memory, and allows the adaptive immune system to mount faster and stronger attacks each time this pathogen is encountered.

Personality and gene expression: Do individual differences exist in the leukocyte transcriptome? Psychoneuroendocrinology, Volume 52, Issue null, Pages 72-82 DOI: Kavita Vedhara, Sana Gill, Lameese Eldesouky, Bruce K. Campbell, Jesusa M.G. Arevalo, Jeffrey Ma, Steven W. Cole

Litman GW, Cannon JP, Dishaw LJ (November 2005). “Reconstructing immune phylogeny: new perspectivesNature Reviews Immunology 5 (11): 866–79

Photo credits, top to bottom: Atikh Bana, Aimanness Photography

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