Ground-breaking research led by University of Limerick has revealed for the first time that the immune system directly links personality to long-term risk of death.
The study sheds new light on why people who are more conscientious tend to live longer.
Results from the new international study published in the journal Brain, Behavior, and Immunity have found that the immune system plays a previously unknown role in the link between personality traits and long-term risk of death.
"Personality is known to be associated with long-term risk of death, it is a well replicated finding observed across numerous research studies internationally," explained Principal Investigator on the study Dr Páraic Ó Súilleabháin, from the Department of Psychology and Health Research Institute at University of Limerick, Ireland.
"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.
For instance, it has been shown that people scoring lower on the personality trait of conscientiousness (a tendency to be responsible, organized, and capable of self-control) can be at a 40% 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," added Dr Ó Súilleabháin.
Led by Dr Ó Súilleabháin, this study was conducted with a team of collaborators from the Department of Psychology at UL, the Department of Psychology at West Virginia University, the Department of Psychology at Humboldt University Berlin, and the College of Medicine at Florida State University.
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 was drawing 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. 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."
Dr Ó Súilleabháin, Department of Psychology, UL
O'Súilleabháin, P.S., et al. (2021) Personality pathways to mortality: Interleukin-6 links conscientiousness to mortality risk. Brain, Behavior, and Immunity. doi.org/10.1016/j.bbi.2021.01.032.