How Does Cardiorespiratory Fitness Affect Cognitive Function in Middle Age?

David R. Jacobs Jr, PhD Divisions of Epidemiology School of Public Health University of Minnesota, Interview with:
David R. Jacobs Jr, PhD
Divisions of Epidemiology
School of Public Health
University of Minnesota, Minneapolis What are the main findings of this study?

Dr. Jacobs: Vigorous activity is what is well understood to improve cardiorespiratory fitness. People with high fitness are likely (based on this study) to

a) Lose fitness more slowly as they age and

b) To maintain sharper “thinking skills” into late middle age.

I think the message of this study is primarily for the people in the low to mid range of fitness in young adulthood.  Thus, of more importance to the general population, if the people with low to moderate fitness simply do things, be engaged in family, job, community, move around, they would  be able to do better on a treadmill test such as we used.  Because those who lost less fitness over average age 25 to average age 45 had higher thinking skills at age 50, people who start moving around are likely to reap the benefit of less loss of thinking skills by average age 50. How does cardiovascular fitness actually help to preserve memory/thinking skills?

 Dr. Jacobs:  How brain function, “thinking skills” work is not well understood.  One point is that the brain requires lots of oxygen which is delivered by blood vessels.  Therefore behaviors and physical aspects that are good for the blood vessels (the vasculature) are also good for the brain.  There are probably many other ways in which fitness and maintaining an active life are beneficial.  One is tuning up mitochondria, which are central in maintaining energy turnaround in the body.  From the perspective of individual and societal decision making, the mechanisms are less important, however; probably people who have poorer thinking skills in middle age have lesser jobs and less income, for example.  The empirical finding is very helpful that thinking skills are higher in people who had better fitness in youth and who maintained for many years. Why is the CARDIA study so important to people (like runners) who try to main high fitness?

Dr. Jacobs:  The CARDIA study is important to everyone because it shows that association of “better thinking skills” in middle age with higher fitness across the range of fitness: from moderate fitness is better than low fitness and high fitness is better than moderate fitness.  People should use their bodies, they should move their bodies.  For those capable of high intensity activity, such as running or jogging, those are good activities.  More generally, people should use their bodies to participate in their families, jobs, and community.  Using your physical capacities keeps you thinner and promotes other activity associated with living.  How might improved cardiorespiratory fitness as a young man benefit verbal memory and other brain functions 25 years down the road?

Dr. Jacobs:  We don’t know how it works, or if changes in fitness actually help (this would be subject of intervention studies, whereas our study is observational).  Much of cognitive loss is mediated by vascular problems, so effects of fitness or on activity that leads to better fitness could operate through the same pathways as any cardiovascular disease risk factor works.  The treadmill test we did involves many aspects of life, from heart and lung fitness to joint health to motivation and usual participation in activity.  Even simple engagement with family and community can improve fitness, for example by not smoking, by maintaining lower body fatness, and by having a positive attitude towards moving your body.  My guess is that better fitness incorporates all of these aspects of engagement and health. What would your advice be to younger men? (How much cardio is optimal? And might certain types–swimming or running–be better than others?)

Dr. Jacobs:  My advice to young men is to be active and engaged in family, community and life in general.  Vigorous activity is well known to influence fitness.  The “use it or lose it” principle applies in young men as in everyone; fitness is harder to recover the older one gets.  I do not have advice about specific activities; any vigorous activity will do, and can be tailored to the life of each young man.  More deeply, though, not smoking and being engaged with family and community will get a young man moving, and likely have a positive influence on fitness, even if no vigorous activities are done. Do you or your colleagues have any plans for future research, given your new findings?

Dr. Jacobs:  CARDIA has several unique features among studies.  It is a life course study, first examining people at age 18-30 and about to enter its 9th detailed examination at age 48-60, 30 years later.  We can link relative youth to late middle age.  The hope is to carry this through old age, which will give a glimpse of how youth affects old age.  We have already published several studies showing relationships of youth lifestyle and physical status with cognitive function in late middle age; more papers are in the pipeline.  Funding permitting (which depends on the funding for the National Institutes of Health), we will continue study of cognitive function.


Cardiorespiratory fitness and cognitive function in middle age The CARDIA Study

Na Zhu, MD, MPH, David R. Jacobs Jr, PhD, Pamela J. Schreiner, PhD, Kristine Yaffe, MD, Nick Bryan, MD, PhD, Lenore J. Launer, PhD, Rachel A. Whitmer, PhD, Stephen Sidney, MD, MPH, Ellen Demerath, PhD, William Thomas, PhD, Claude Bouchard, PhD, Ka He, MD, ScD, Jared Reis, PhD and Barbara Sternfeld, PhD

Published online before print April 2, 2014, doi: 10.1212/WNL.0000000000000310