Link between personality and risk of death

Ground-breaking research 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.

What the researchers say: "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 the principal investigator on the study. "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."

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.

The researchers explained: "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," they concluded.

So, what: This is a very interesting study when aligned with the many recent studies into personality. We know that personality traits are about 25% genetically based. However, the genes responsible for personality traits are altered in their expression by experience (especially childhood experience), present relationship environment and context.

A “conscientious” person may be conscientious in one context and one set of relational surroundings and quite the opposite in others (which is why most psychometric tests, such as the infamous MBTI, are scientific nonsense).

For that reason, the morbidity danger seen by this study must relate to the underlying genetic predisposition—the 25 (or so)%. A person is therefore in danger of dying earlier not because their behavior is less than conscientious but because their individual DNA predisposes them to a certain personality trait which may never be actualized.

I think before we use the study’s conclusions for “future interventions” a lot more study needs to be done. At the moment we have no certainty as to which genes predispose particular personality traits.