Lifespan Physical Activity Profile, Cognitive Function And Brain Metabolism In Old Age

Abstract

PURPOSE: Physical activity during adulthood is discussed as a major preventive factor against loss of cognitive function in old age. The present study aims at analyzing the effects of lifetime physical activity (PA) on cognitive function and brain metabolism. METHODS: Data were obtained from 50 cognitively unimpaired elderly subjects (72±5yrs, 27♀). Lifetime leisure PA was assessed by a validated questionnaire investigating five epochs across the lifespan (age in years: 14-21, 22-34, 35-50, 51-65, 66-80). Data were analyzed as average energy consumption (MET-h/wk) per epoch. Participants individual lifespan activity profile was defined as the behavior they engaged in for at least 60% of their lifetime (≥3 epochs). Referring to current activity guidelines (7.5 MET-h/wk ≈ 75’ vigorous or 150’ moderate PA-min/wk) and based on the individual activity profiles, subjects were stratified in 3 groups of lifetime activity behavior (MET-h/wk: <7.5/7.5-15/>15). Cognitive assessment included testing of executive function (stroop interference test), verbal and non-verbal declarative memory and crystallized intelligence (MWT-B). Brain metabolism was recorded from a transversal slice just above the corpus callosum via magnetic resonance spectroscopic imaging (MRSI), and analyzed as the ratio of N-Acetylaspartate to choline (NAA/tCho). RESULTS: Compared to individuals reporting less than the recommended minimum of 7.5 MET-h/wk (460ms), ANCOVA revealed significantly (p<.05) higher NAA/Cho values and shorter mean response times for stroop word test among those performing the recommended minimum (-50ms) and those performing ≥2 times the minimum (-60ms). Stroop interference scores were solely higher in participants performing ≥2 times the minimum recommendation. Correlation analysis showed significant associations of overall and vigorous mean lifetime PA with stroop performance (r=.408; r=.410; p<.05) and NAA/Cho (r=.303; r=.310; p<.05). CONCLUSIONS: The findings suggest that lifelong adherence to the minimum recommended amount of health enhancing PA results in positive effects on executive function and neuronal metabolism in old age. Exceeding minimum guideline recommendations in terms of intensity and duration might lead to additional benefits.