The immune system plays a role in the link between personality traits and long-term risk of death, new research led by the University of Limerick (UL) has found.
The study sheds new light on why people who are more conscientious tend to live longer.
The results from the study, which was conducted by a team of collaborators from the departments of psychology at UL, West Virginia University, Humboldt University Berlin and the College of Medicine at Florida State University, were published in the journal Brain, Behaviour and Immunity.
Principal investigator on the study, Dr Páraic Ó Súilleabháin, from the Departent of Psychology and Health Research Institute at UL said personality is known to be associated with long-term risk of death.
“It is a well replicated finding observed across numerous research studies internationally,” he said. “The critical question is ‘how’. We wanted to find out if a biological pathway such as our immune system may explain why this happens.
“Our personality is critically important throughout our lives, from early stages in our development, to the accumulation of the impact of how we think, feel and behave across our lives, and in the years preceding our death. It is also becoming increasingly apparent how important personality actually is for our long-term health and resulting longevity.”
Dr Ó Súilleabháin said it has been shown that people scoring lower on the personality trait of conscientiousness, a tendency to be responsible, organised, and capable of self-control, can be at a 40 per cent increased risk of future death compared to their higher scoring counterparts.
“What is not clear is how this could happen, and importantly, what biological pathway might be responsible for this link,” he added.
The researchers wanted to investigate if two biological markers which are central to the immune system may explain why personality traits are associated with long-term mortality risk.
Specifically, they wanted to test if interleukin-6 and c-reactive protein which are known to play an important role in age-related morbidity may explain how our personality traits are related to how long we live.
The study drew on data from the Midlife in the United States Longitudinal Study carried out on 957 adults who were examined over a 14-year period.
“We found that part of the reason why people who score higher on the personality trait of conscientiousness live longer is as a result of their immune system, specifically due to lower levels of a biological marker called interleukin-6,” Dr Ó Súilleabháin explained. “There are likely further biological mechanisms that are yet to be discovered which will give a clearer picture of all the different ways that our personalities are so critical to our long-term health.
“These findings are very important and identify for the first time that an underlying biological marker directly links personality to long-term mortality risk. With replication, these findings provide an opportunity for future interventions to increase our longevity and health across the lifespan.”