The Association Between Sedentary Behavior and Cognitive Function Among Older Adults May Be Attenuated With Adequate Physical Activity

OBJECTIVE: Examine the independent association of sedentary behavior and cognitive function in older adults, as well as whether physical activity attenuates this potential association. METHODS: Data from the 1999-2002 National Health and Nutrition Examination Survey were used (N = 2472 adults 60 to 85 yrs). Sedentary behavior was subjectively assessed and the Digit Symbol Substitution Test (DSST) was employed to assess cognitive function. RESULTS: Among an unadjusted and an adjusted model not accounting for physical activity, only 5+ hrs/day (vs. < 1 hr) of sedentary time was independently associated with lower DSST scores (β = -3.1; 95% CI: -5.8 to -0.4; P= .02). However, a fully adjusted model (adding in moderate-to-vigorous physical activity as a covariate) did not yield a statistically significant association between 5+ hrs/day of sedentary time and DSST scores (β = -2.5; 95% CI: -5.1 to 0.2; P = .07). CONCLUSION: Accumulated daily sedentary behavior of 5+ hrs is associated with lower cognitive function in an older adult population when physical activity is not taken into account. However, physical activity may account for 19% of the total association between sedentary behavior and cognitive function, thus attenuating the sedentary-cognitive function association. Efforts should be made to promote physical activity in the aging population.