Human Limits

Exploring performance and health with Michael J. Joyner, M.D.

Photo of Michael J. Joyner, M.D.

Exercise, Cognition & Conscientiousness

My last two posts have focused in part on the relationship between physical activity and cognitive function.   Today I want to make two simple points and connect them.   The first is from another Cooper Clinic database study and looks at the association between midlife physical fitness in about 20,000 people and a later diagnosis of dementia.   The subjects were divided into fitness quintiles and followed for about 25 years.  The figure below shows that individuals in the highest fitness quintiles had only about 64% of the risk of a dementia diagnosis compared to the least fit subject.   Importantly, the level of exercise training needed to move up several fitness quintiles is modest and consistent with standard physical activity guidelines for adults, e.g. 150 minutes per week of vigorous walking.




The second point I want to make is that a psychological trait known as conscientiousness is also associated with healthy aging and a modest increase in longevity.   In a longitudinal study of aging conducted in about 2,400 residents of Baltimore, Maryland who were followed for five decades, people who scored high for conscientiousness lived longer.   General activity, a marker of who is extroverted or “outgoing”, and emotional stability were also traits associated with living 2-3 years longer.




There are a couple of ways fitness and conscientiousness might be connected.   The first is pretty straight forward and perhaps conscientious people just plain exercise more and generally follow health and lifestyle related guidelines about exercise, diet, not smoking and things like wearing seat belts.  The second explanation is a bit more subtle and relates to the effects of exercise on something called executive functions.  If exercise and physical activity enhance areas of the brain involved with executive functions — the ability to plan, stay on task, and pay attention — then people might be more likely to engage in healthy activities over time.  If exercise helps maintain executive functions as we age then perhaps it is “easier” or more automatic for people to continue to stay fit as they age.   So perhaps this is not so much about fixed personality traits as it is about exercise and conscientiousness reinforcing or amplifying a positive suite of behaviors over time.

None of this would surprise my grandmother who was born in the early 1900s and ultimately became a pioneer special education teacher in rural Indiana.   She made sure all of her grandchildren and just about every other young person she came in contact with was exposed to books like The Little Engine That Could.  I am sure she would not be surprised by the idea that good habits and a positive attitude generate more good habits and a positive attitude over time.   To her that was a fundamental piece of Midwestern common sense.


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