Extraversion and Conscientiousness Personality Traits Linked to Pro-Inflammatory Genes Expression

Extraversion and Conscientiousness – Pro-Inflammatory

A study published in the journal Psychoneuroendocrinology demonstrates that leukocyte gene expression correlates with two major dimensions of human personality, extraversion and conscientiousness.

Personality is commonly defined as a cluster of individual psychological attributes, which are typically stable across time and situations and give rise to enduring individual differences.

Multivariate analyses have generally identified 5 major dimensions of human personality – Neuroticism, marked by a tendency toward negative affect; Extraversion characterized by high levels of sociability and appetitive motivation; Openness to Experience, which reflects general curiosity, creativity, and an orientation toward intellectual and aesthetic pursuits; Agreeableness, reflecting general likability and even temperament; and Conscientiousness, reflecting planfulness, caution, and harm avoidance.

A recent study in nonhuman primates provides new insights into the neuroanatomical basis of personality, showing that personality traits are linked to the anatomy of specific brain structures such as the anterior cingulate cortex and the brain prefrontal cortex.

The temporal and situational stability of personality has led generations of researchers to hypothesise that personality may have enduring effects on health. And some large epidemiological studies have found associations between personality characteristics and measures of disease or longevity.

Several causal models have been invoked to explain associations between personality and health, including common causation by underlying individual differences in genetics or early life experience; effects of personality on health behaviour, etc.

One body of theoretical analysis suggests that individual differences in the vigour of biological immune responses may come to be associated with individual differences in personality traits that serve as a sort of ‘behavioural immune response’. According to this theoretical approach, individuals who have relatively weak biological immune responses are hypothesized to show stronger behavioural immune responses such as avoidance of strangers (i.e., Introversion), reduced exploratory behaviour (i.e., low Openness to experience), and greater harm-avoidant behaviour (i.e., Conscientiousness).

Conversely, allostatic physiology suggests that biological immune defences may be up-regulated in individuals who experience extended exposure to threat or stress and might thus experience an elevated risk of injury or infection, or in highly sociable individuals who face increased exposure to communicable diseases.

Research in the neuroscience of personality has also provided connections between dopaminergic neurotransmission, and the reward-processing functions of the dopamine system and various aspects of personality and individual differences.

For centuries, personality traits have been linked to health status and outcome. New research indicates that the frontal cortex of the brain and asymmetries in this region may constitute the neurobiological foundation of broad personality traits.

In the Psychoneuroendocrinology study the research teams from the University of Nottingham, UK; the Washington University, St. Louis, and the University of California, Los Angeles, USA utilized a functional genomics approach to identify relationships between the 5 major dimensions of human individual differences in personality and broad patterns of gene expression in human leukocytes.

The authors dentified systematic differences in leukocyte gene expression that correlate with individual differences on two major dimensions of human personality: Extraversion and Conscientiousness.

Consistent with predictions from behavioural immune response theory the investigators provide evidence that extraversion is associated with up-regulated expression of pro-inflammatory genes, whereas conscientiousness is associated with down-regulated expression of pro-inflammatory genes.

The pattern of associations between leukocyte CTRA gene expression and specific dimensions of human personality are largely as would be predicted by the behavioural immune response hypothesis i.e., that stable individual differences in behaviour arise in response to stable individual differences in biological vulnerability to infection.

Interestingly, as personality may be associated with inflammation, recent research also indicates that personality traits such as conscientiousness and neuroticism are associated with levels of the pro-inflammatory cytokine interleukin (IL)-6 [A.R. Sutin et al., 2010; N.A. Turiano et al., 2013].

Despite the fact that causality and the biological mechanisms behind these associations remain poorly understood, further research along these lines may provide new insights into the well-known epidemiological associations between personality and physical health.

Source: Psychoneuroendocrinology
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