According to a recent study, a person's personality determines the ability to withstand stress-related inflammatory diseases.
Led by researchers at the University of Rochester Medical Center, the study suggests that, especially in ageing women, low levels of the personality trait extraversion may signal that blood levels of a key inflammatory molecule have crossed over a threshold linked to a doubling of risk of death within five years.
The researchers point out that long-term exposure to hormones released by the brains of people under stress takes a toll on organs, and just like any injury, this brings a reaction from the body's immune system, including the release of immune chemicals that trigger inflammation in an attempt to begin the healing process.
They say that the same process goes too far as part of diseases from rheumatoid arthritis to Alzheimer's disease to atherosclerosis, where inflammation contributes to clogged arteries, heart attacks and strokes.
The current study has shown that extroverts, and in particular those with high "dispositional activity" or engagement in life, have dramatically lower levels of the inflammatory chemical interleukin 6 (IL-6).
The researchers used a 'Five Factor Model' of personality- extraversion vs. introversion, emotional stability vs. neuroticism, openness vs. closed-minded, agreeable vs. hostile, and conscientiousness vs. unreliability-to organise hundreds of specific traits like "activity" for psychologists, similar to the way the Periodic Table organizes elements for physicists.
"Our study took the important first step of finding a strong association between one part of extroversion and a specific, stress-related, inflammatory chemical," said lead author Dr. Benjamin Chapman, assistant professor within the Rochester Center for Mind-Body Research (RCMBR), part of the Department of Psychiatry at the University of Rochester Medical Center.
"The next step is to determine if one causes the other. If we knew the direction and mechanism of causality, and it were low dispositional activity causing inflammation, we could design treatments to help high-risk patients become more engaged in life as a defence against disease," the researcher added.
The current analysis agrees with the past studies that contended that women and minorities have higher levels of IL-6 than white males on average.
The team gauged the magnitude of IL-6 associations for gender, race/ethnicity and personality by examining the degree to which each factor was associated with differences between people in IL-6.
Of the differences in inflammation found in the patient sample in levels of IL-6, about 9 percent of the difference was due to gender, 6 percent was due to dispositional activity levels and another 4 percent to race/ethnicity.
The researchers agree that it may be very difficult for patients to change their nature, but suggest that physical exercise may be used as a therapy because the activity component of extraversion has been linked with exercise by past studies, as has daily physical activity with lower IL-6 levels in the ageing.
However, the team is still not convinced that exercise represents the whole answer.
"Beyond physical activity, some people seem to have this innate energy separate from exercise that makes them intrinsically involved in life. It will be fascinating to investigate how we can increase this disposition toward engagement.
Potentially, you might apply techniques developed to treat depression like 'pleasurable event scheduling' to patients with low dispositional energy, where you get people more involved in life by filling their time with things they enjoy as a therapy," Chapman said.
The study has been published in the journal Brain, Behavior and Immunity.