It’s long been thought that some aspects of personality may be linked to health and wellbeing – from how much we sleep, to how we cope with illness and even how long we live.

Now researchers believe extroverts may have a healthy edge – by being better at fighting off infections.

Health psychologists at The University of Nottingham and the University of California in Los Angeles (UCLA) asked a group of 121 ethnically diverse and healthy adults to completed a personality test and found that outgoing people may have stronger immune systems.

The study did not find any results to support theories that negative emotions such as depression or anxiety can lead to poor health. But it suggested differences in immune cell gene expression were related to a person’s degree of extroversion and conscientiousness.

Gene expression analysis was carried out at the Social Genomics Core Laboratory at UCLA and microarray technology examined relationships between the five major human personality traits – extroversion, neuroticism, openness, agreeableness and conscientiousness – and two groups of genes active in human white blood cells (leukocytes): one involving inflammation, and another involving antiviral responses and antibodies.

Leading the research, Professor Kavita Vedhara, from Nottingham’s School of Medicine, said: “Our results indicated that ‘extroversion’ 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 (ie, extroverts) 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?”

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 biological mechanisms of these associations need to be explored in future research but the data may shed new light on the long-observed associations between personality, physical health, and human longevity.

Personality and gene expression: Do individual differences exist in the leukocyte transcriptome? by Kavita Vedhara, Sana Gill, Lameese Eldesouky, Bruce Campbell, Jesusa Arevalo, Jeffrey Ma and Steven Cole, is available online  here  in Psychoneuroendocrinology, an Elsevier journal.