Examine the independent association of sedentary behavior and cognitive function in older adults, as well as whether physical activity attenuates this potential association.
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.
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).
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.