By William C. Haas III, MD, MBA
Integrative Medicine Fellow, Department of Family and Community Medicine, University of Arizona, Tucson
SYNOPSIS: Peak levels of cardiorespiratory fitness are positively correlated with enhanced cognitive function among older adults.
Cognitive function may be enhanced by high levels of cardiorespiratory fitness in older adults.
SOURCE: Freudenberger P, Petrovic K, Sen A, et al. Fitness and cognition in the elderly: The Austrian Stroke Prevention Study. Neurology 2016;86:418-424.
In spite of a wealth of evidence that almost universally indicates that regular physical activity has tremendous benefits, only a small percentage of older adults actually exercise for the minimum recommended amount of time per week. The trend among the elderly toward physical inactivity is seriously concerning, especially as recent research indicates that physically active adults have significantly lower risk of cognitive decline and dementia. Any and all efforts to slow rates of cognitive decline and dementia are certainly important, as cognitive decline carries with it severe social and economic problems for patients. Breakthroughs in this field are doubly valuable given that there is a lack of effective treatment options for cognitive decline.
While the exact mechanisms by which physical activity can serve as a neuroprotective measure are unclear, one potential answer is that improved cardiovascular (CV) fitness reduces the risk for cerebrovascular disease. CV fitness is often quantified—albeit imperfectly—by the body’s maximum capacity to consume oxygen (VO2max). CV health may well play a serious role in aging’s increased risk for cerebrovascular disease, as CV fitness tends to decline with age. This decline can be remedied, and perhaps even reversed, however, by regular physical activity.
Freudenberger et al, seeking to clarify the implications of the conclusions in the original Austrian Stroke Prevention study, conducted a follow-up cohort study to delve further into the role CV fitness plays in the participants’ cognitive abilities. The authors enacted their follow-up by sampling 877 patients recruited from the first study. The initial Austrian prevention study was community-based and evaluated the roles that various CV risk factors played in shaping brain structure and affecting cognitive function in elderly patients without prior history of dementia or stroke. The primary purpose was to determine the effect of VO2max on cognitive ability and rates of dementia. The follow-up study put patients through even more testing than its predecessor, ensuring that participants took cognitive tests, exercise ECGs, and MRIs. The cognitive tests comprised a series of validated exams testing patients’ memory, executive function and motor skills. The exercise ECG results were used to estimate VO2max, while MRI testing revealed any potential lacunar infarct burden, white matter lesions, or atrophy. Accounting for secondary variables, Freudenberger et al assessed a multitude of CV risk factors like cigarette smoking, hypertension, cholesterol, diabetes, and body mass index.
Regarding the primary outcome marker, VO2max demonstrated positive, linear trends for enhanced memory, global cognition, and executive function. The difference in the effect size between highest and lowest quartiles of VO2max for memory, global cognition, and executive function were 0.298, .260, and 0.117, respectively. There was another intriguing trend, in that the differences between individuals in the highest and lowest quartiles also corresponded to significant age differences. The mean age differences between the quartiles were six years for memory, four years for global cognition, and seven years for executive function. Lastly, in analysis of secondary outcomes, it was determined that the effect VO2max had on cognitive was not affected by the presence of white matter lesions, atrophy or lacunar infarcts.