The Cooper Institute

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH


Cardiorespiratory Fitness and Cognitive Function: What’s the Connection?

Posted in
Live well

Thursday, May 31, 2018

As the median age of U.S. adults continues to increase, the issue of maintaining a healthy brain later in life becomes of paramount importance. There are data to suggest that regular physical activity (PA) may be helpful in this regard. PA is typically estimated via self-report questionnaires, which can be imprecise either due to the questionnaire itself or due to the respondent. While related to physical activity, cardiorespiratory fitness (CRF) is actually a different variable because it can be measured objectively by a maximal treadmill exercise test. Of the two, CRF has been shown to be a stronger predictor of future health outcomes than PA.

An important goal for healthy aging is 
maintenance of cognitive function, and there are a number of different tests to evaluate it. One of these is the Montreal Cognitive Assessment (MoCA), a paper and pencil screening tool that takes about 10 minutes for a trained technician to administer. The test, scored on a scale of 0-30 points, is designed to identify cognitive impairment by assessing multiple cognitive domains including attention, concentration, memory, language, calculation, and other important factors. MoCA scores between 26 and 30 are considered normal while scores <26 indicate cognitive impairment.

Because studies in this area are rather sparse, we examined the relationship between CRF and cognitive impairment in a sample of 4,931 older Cooper Clinic men and women. Subjects were 61 years old on average and were examined between 2008 and 2017. All underwent a maximal treadmill exercise test to measure CRF, as well as the MoCA screening to evaluate cognitive function. About 92% of the sample were white, while 72% were male. Of the 4,931 subjects, 23.4% had some degree of cognitive impairment (MoCA score <26). We placed the subjects into 5 categories of CRF based on their age, sex, and treadmill test performance to determine if there was any relationship between CRF and cognitive impairment.

The results, as shown in the Figure below, are clear. The more fit the subject, the less chance that subject displayed cognitive impairment.

To examine it more closely, the figure shows that the percentage of individuals with cognitive impairment decreased as the CRF category increased. For example, while 33% of those who were the least fit had cognitive impairment, only 19.3% of those who were the
 most fit had cognitive impairment. We also found that for every 2-minute improvement in treadmill test performance, there was a 7% reduction in the risk of having cognitive impairment.   

Because this was a cross-sectional study (best thought of as a single snapshot at one point in time), we can say that there is a significant association between CRF and cognitive function. In other words, heart health is tied to brain health. However, we cannot say that having a higher level of CRF causes an individual to have a lower risk of cognitive impairment - the limitation of cross-sectional studies is that cause and effect cannot be determined. Additional studies should be done in order to determine if improvements in CRF over time are associated with
improved cognitive function.

This paper compliments a 2013 paper by DeFina et al. which showed that having at least a moderate level of CRF at midlife was associated with a significantly reduced risk of developing all-cause dementia later in life.

Farrell, S., Abramowitz, A., Willis, B., Barlow, C., Weiner, M., Falkowski, J., Leonard, D., Pavlovic, A., DeFina, L. (2018). The Relationship between Cardiorespiratory Fitness and Montreal Cognitive Assessment Scores in Older Adults. Gerontology, e-pub ahead of print. DOI:10. 1159/000489336