Beyond vascularization: Aerobic fitness is associated with N-acetylaspartate and working memory

Kirk I. Erickson*, Andrea M. Weinstein, Bradley P. Sutton, Ruchika Shaurya Prakash, Michelle W. Voss, Laura Chaddock, Amanda N. Szabo, Emily L. Mailey, Siobhan M. White, Thomas R. Wojcicki, Edward McAuley, Arthur F. Kramer

*Corresponding author for this work

Research output: Contribution to journalArticle

59 Scopus citations

Abstract

Aerobic exercise is a promising form of prevention for cognitive decline; however, little is known about the molecular mechanisms by which exercise and fitness impacts the human brain. Several studies have postulated that increased regional brain volume and function are associated with aerobic fitness because of increased vascularization rather than increased neural tissue per se. We tested this position by examining the relationship between cardiorespiratory fitness and N-acetylaspartate (NAA) levels in the right frontal cortex using magnetic resonance spectroscopy. NAA is a nervous system specific metabolite found predominantly in cell bodies of neurons. We reasoned that if aerobic fitness was predominantly influencing the vasculature of the brain, then NAA levels should not vary as a function of aerobic fitness. However, if aerobic fitness influences the number or viability of neurons, then higher aerobic fitness levelsmight be associated with greater concentrations of NAA. We examined NAA levels, aerobic fitness, and cognitive performance in 137 older adults without cognitive impairment. Consistent with the latter hypothesis, we found that higher aerobic fitness levels offset an age-related decline inNAA. Furthermore, NAA mediated an association between fitness and backward digit span performance, suggesting that neuronal viability as measured by NAA is important in understanding fitness-related cognitive enhancement. Since NAA is found exclusively in neural tissue, our results indicate that the effect of fitness on the human brain extends beyond vascularization; aerobic fitness is associated with neuronal viability in the frontal cortex of older adults.

Original languageEnglish (US)
Pages (from-to)32-41
Number of pages10
JournalBrain and Behavior
Volume2
Issue number1
DOIs
StatePublished - Jan 1 2012

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Keywords

  • Aging
  • Brain
  • Exercise
  • Fitness
  • Human
  • N-acetylaspartate
  • Working memory

ASJC Scopus subject areas

  • Behavioral Neuroscience

Cite this

Erickson, K. I., Weinstein, A. M., Sutton, B. P., Prakash, R. S., Voss, M. W., Chaddock, L., Szabo, A. N., Mailey, E. L., White, S. M., Wojcicki, T. R., McAuley, E., & Kramer, A. F. (2012). Beyond vascularization: Aerobic fitness is associated with N-acetylaspartate and working memory. Brain and Behavior, 2(1), 32-41. https://doi.org/10.1002/brb3.30