Interview with Dr. Dan Mroczek on neuroticism, happiness and longevity

Most people want to live happy and live long. Can you have it all?

The good news: happiness and longevity seem to be positively correlated -- in other words, longer-lived people tend to be happier, and happier people tend to be long-lived.

There is a great deal of research going on in this area. Previous studies have indicated that high neuroticism is associated with earlier mortality. Then a Purdue University researcher found that the relative change in the level of neuroticism also had to be factored in. Neurotic men whose levels dropped over time had a better chance at living longer and seem to recover from any damage high levels of the trait may have caused, while neurotic men whose neuroticism increased over time died much sooner than their peers. (For the purposes of this discussion, a neurotic personality is defined as a "person with the tendency to worry, feel excessive amounts of anxiety or depression and to react to stressful life events more negatively than people with low levels of the trait.")

The originator of this important work is Dr. Dan Mroczek, an associate professor of child development and family studies at Purdue University. Given our interest in happiness, health and longevity, we tracked down Dr. Mroczek and asked him to shed more light on his findings.

LifeTwo: Why are some people generally become happier as they age while others seem to become generally less happy? Is the same true with overall life “satisfaction”?

No one has really been able to answer this definitively, although personality is certainly a major factor that explains why some people grow less satisfied over time. Some people possess high levels of certain personality traits (such as extraversion) that predispose them to feeling more satisfied with life.

LifeTwo: What is the relationship between positive/negative personality traits and physical health?

There are no positive or negative personality traits. Everybody has a value (or amount of) on a given trait, in the same way that everybody has a value on weight, or on height. You have a value on height, and similarly you have a value on extraversion. The better way to think about traits and health is that certain levels of certain traits are associated with better health. People who are high in the trait conscientiousness tend to have better health. And as I found, people with lower levels of neuroticism tend to have better health, although this modified by how much you changed on neuroticism over the long-term.

LifeTwo: Can you tell us about your 12-year neuroticism study that tracked more than 1600 men, why it was important, and what you learned? Why were just men studied?

I only had men available in that data set. The participants were recruited in 1968, when I was only 3 years old! You work with the data you have. I would have preferred if women were part of the sample, but women were not recruited when the study began in 1968. In that 2003 study where I modeled growth-curves of personality, I found that there was a wide range of change on personality traits over 12 years. Some people are stable—they don’t change. But others go up and others go down. That variability in rate of change was associated with mortality, which is what the new publication is about.

LifeTwo: Can you elaborate a little on this? Does science know anything about what is causing these changes?

Here's a way of thinking about your question. Imagine anything else that changes over time. Children's height, adult's blood pressure, BMI, etc. Do we all change at the exact same rate? That is, do all children grow at the exact same rate? Ot learn how to read at the same rate? Or do all of us experience increases in blood pressure at the exact same rate as we grow older?

The answer is no. People vary in rate of change in any variable (height, weight, BP, cholesterol, math ability, personality traits, etc.). No one changes at the same rate. This is what I scientifically documented, before anybody else did, in my 2003 paper on change in personality traits.

As to your question about what causes such variability across people in personality change, think of what might cause variability across people in cholesterol change. Why does Tanya stay stable on LDL lipids, while Wesley goes up? The answer is very complex and requires consideration of both environmental (diet, exercise) and genetic factors. The same is true of personality change.

LifeTwo: Is there a “secret” to happiness?

I don't think so. I think it's complicated. Genetic factors play a big role, but environmental factors can't be ignored either. If you are feeling very unhappy, you may be depressed or have a clinically-diagnosable disorder. I'd get professional help right away if you think that.

+++

The key takeaway from Dr. Mroczek for LifeTwo is that while people with lower levels of neuroticism tend to have better health the change in one's neuroticism must also be factored in. Improving (that is lowering) your level of neuroticism will improve your chances living longer (and a presumably more fulfilling life). More detail on Dr. Mroczek's work can be found at Purdue University's Child Development and Family Studies.

neuroticism