Summary: New research shows the immune system provides a biological link between personality and long-term mortality risk. People who score higher in conscientiousness tend to live longer in part because they have lower levels of the inflammatory marker interleukin‑6 (IL‑6).
Source: University of Limerick
Groundbreaking research led by the University of Limerick reveals for the first time that an immune marker directly connects personality traits with long-term risk of death.
The study clarifies one biological pathway that helps explain why people who are more conscientious—those who tend to be responsible, organized, and self-disciplined—generally live longer than less conscientious individuals.
Published in the journal Brain, Behavior, and Immunity, the international study identifies the immune system, and specifically interleukin‑6, as a mediator in the relationship between personality and mortality over time.
“Personality has long been associated with mortality risk in many studies around the world,” said Principal Investigator Dr Páraic Ó Súilleabháin from the Department of Psychology and the Health Research Institute at the University of Limerick. “The central question we sought to answer was how this happens. We investigated whether a biological pathway such as immune function might explain the link.”
Dr Ó Súilleabháin noted that personality shapes behavior, choices, and health across the lifespan—from early development to the years before death—and that understanding the biological mechanisms involved can clarify how personality affects long-term health and longevity.
For example, previous evidence indicates that people with lower conscientiousness can face roughly a 40% higher risk of future death compared with those who score higher on conscientiousness. What was uncertain until now was which biological processes underlie that association.
This study was led by Dr Ó Súilleabháin with collaborators from the University of Limerick, West Virginia University, Humboldt University Berlin, and Florida State University College of Medicine.
The researchers examined two immune-related biomarkers that are central to inflammation and age-related disease: interleukin‑6 (IL‑6) and C‑reactive protein (CRP). Both markers have been linked to age-related morbidity, but their roles in connecting personality traits to mortality had not been tested in a large, long-term sample.
Using data from the Midlife in the United States (MIDUS) longitudinal study, the team analyzed 957 adults who were followed over 14 years. The sample included a broad age range and allowed the researchers to model how personality traits, biomarker levels, and mortality risk were related across time.
The study found that higher conscientiousness was associated with substantially lower mortality risk: each one standard deviation increase in conscientiousness corresponded to an approximately 35% reduction in mortality hazard. Importantly, IL‑6—but not CRP—partially mediated this relationship. In the fully adjusted models, IL‑6 accounted for about 18% of the association between conscientiousness and mortality.
Dr Ó Súilleabháin commented, “Our results suggest that part of why more conscientious people live longer is that they tend to have lower IL‑6, an inflammatory marker implicated in aging and disease. There are likely additional biological and behavioral pathways that contribute, and future research should continue to map these mechanisms.”
The authors emphasize that these findings are an important step in identifying measurable biological processes that link personality with long-term health outcomes. With replication, this pathway could inform interventions aimed at reducing inflammation and improving longevity across different personality profiles.
About this mortality and personality research news
Source: University of Limerick
Contact: Alan Owens – University of Limerick
Image: The image is in the public domain
Original Research: Open access. “Personality pathways to mortality: Interleukin‑6 links conscientiousness to mortality risk” by Páraic S O’Súilleabháin, Nicholas A Turiano, Martina Luchetti, Denis Gerstorf, Stephen Gallagher, Amanda Sesker, Antonio Terracciano, Angelina R Sutin. Brain, Behavior, and Immunity. DOI: 10.1016/j.bbi.2021.01.032
Abstract
Personality pathways to mortality: Interleukin‑6 links conscientiousness to mortality risk
Personality traits consistently predict mortality risk, but the physiological pathways that explain this pattern are not fully understood. One plausible mechanism is immune system dysregulation, since chronic inflammation contributes to many age‑related diseases and increased mortality.
In this preregistered analysis, the authors tested whether IL‑6 and CRP mediated the association between major personality traits and mortality hazards. The sample included 957 participants (mean age 58.65 ± 11.51 years; range 35–86) from the MIDUS study, with 14 years of follow-up data.
Higher conscientiousness predicted lower mortality hazard: one standard deviation higher conscientiousness was associated with a 35% lower mortality risk. IL‑6, but not CRP, partially mediated this association; IL‑6 explained approximately 18% of the conscientiousness–mortality link in fully adjusted models. Initial indications that biomarkers mediated the effects of neuroticism and agreeableness on mortality were attenuated after accounting for sociodemographic covariates.
Overall, the findings suggest that greater conscientiousness may contribute to longer life in part through lower IL‑6 levels, highlighting the role of biological pathways that connect personality to future mortality risk.