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An outgoing personality — especially in senior women — may increase the human ability to withstand stress

Our ability to withstand stress-related, inflammatory diseases may be associated, not just with our race and sex, but with our personality as well, according to a study published in the July issue of the journal Brain, Behavior and Immunity. Especially in aging 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.

An emerging area of medical science examines the mind-body connection, and how personality and stress contribute to disease in the aging body. Long-term exposure to hormones released by the brains of people under stress, for instance, takes a toll on organs. 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. 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 found that that extroverts, and in particular those high “dispositional activity” or engagement in life, have dramatically lower levels of the inflammatory chemical interleukin 6 (IL-6). Swiss psychiatrist Carl Jung defined extroverts as focused on the world around them and most happy when active and surrounded by people. Introverts looked inward and were shy.

The definitions of extraversion and other personality traits were refined by American psychologist Gordon Allport beginning in the 1930s. He reviewed all adjectives in the dictionary used to describe personality, and attempted to group them into clusters. Over the next several decades, researchers statistically analyzed these dictionary terms and discovered that they tended to cluster into five general dimensions: extraversion vs. introversion, emotional stability vs. neuroticism, openness vs. closed-minded, agreeable vs. hostile, and conscientiousness vs. unreliability. These dimensions, known as the “Five Factor Model” of personality, served to organize 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 Benjamin Chapman, Ph.D., assistant professor within the Rochester Center for Mind-Body Research (RCMBR), part of the Department of Psychiatry at the University of Rochester Medical Center, and lead author of the study. “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 defense against disease.”

Some past studies had contended, and the current analysis agreed, that women and minorities have higher levels of IL-6 than white males on average. Women may be more vulnerable to stress because of hormonal differences and minorities because of factors like perceived racism, but those questions have yet to be fully answered. While these trends exist, variations within these large groups are so great that further risk markers are needed to better determine any given patient’s actual risk. The current study looked whether particular personality traits, including low extraversion, were associated with IL-6 levels in a sample of 103 urban primary care patients aged 40 and older.

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