Can physical activity mitigate the effect of systemic inflammation on cognitive performance? Results from a large older community dwelling population in the Netherlands

Abstract

Background Elevated systemic inflammation has been linked to poorer cognitive outcomes. Vigorous physical activity is associated with improved cognitive performance. This study investigates whether physical activity moderates the relationship between systemic inflammation and cognition. Methods Using the first wo waves from the Dutch Lifelines cohort study (N = 24,661, 50+), cognitive performance was assessed using a composite score from the Cogstate Brief Battery, with higher scores indicating lower cognitive performance. As a biomarker of systemic inflammation (SI), we used leukocyte count within the normal range of 3 to 11x10⁹ cells per liter in EDTA blood samples in waves 1 and 2. We differentiated between low SI (< 6.5x10⁹ cells per liter) and increased SI ( > = 6.5x10⁹ cells per liter) and distinguished between 4 groups: (1) Persons, who had low SI in both waves; (2) Persons, who had increased SI in wave 1, but low SI in wave 2; (3) Persons, who had low SI in wave 1, but increased SI in wave 2; and (4) Persons, who had increased SI in both waves. We performed linear regression models to examine the effect of inflammation and vigorous physical activity on cognition, adjusting for cognitive task accuracy, age, sex, physical activity, education, medical conditions, and smoking status associated with cognitive impairment. An interaction effect was used to analyze the potential moderation of physical activity. Results Individuals with high systemic inflammation (SI) levels in both waves exhibited significantly longer reaction times (b = 0.061 [0.001;0.121]) compared to those with low SI levels in both waves. Individuals who engage in vigorous physical activity had significantly faster reaction times (-0.152 [-0.198;-0.107]) compared to those who do not. The interaction term was insignificant meaning that all individuals benefit from vigorous physical activity in terms of their cognitive performance, regardless of their SI group. Conclusions Our findings suggest that elevated systemic inflammation is a risk factor for cognitive impairment in older adults, and that physical activity may mitigate this risk. Therefore, promoting physical activity among the aging population may be an effective strategy to prevent or delay cognitive decline and dementia by potentially preventing systemic inflammation.