Long-term patterns of low physical activity and cognitive function in mid-life: the CARDIA Study

Abstract

Few studies have investigated whether physical activity in early to mid-life is associated with cognitive function even though this may be a critical period for establishing life-long activity habits. We investigated the relationship between long-term patterns of low physical activity over 25 years with cognitive function in mid-life. In a biracial cohort of 3,375 adults, (ages 18–30 years) enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) Study (1985–86) and followed for 25 years, physical activity was assessed at repeated visits (≥3 assessments) using a validated physical activity questionnaire and cognitive function was evaluated at the end of follow-up, Year 25. A long-term pattern of low physical activity over 25 years was defined as reporting activity levels within the bottom tertile (<247 exercise units) of baseline physical activity scores for >2/3 rds of completed visits. Cognitive function was assessed using the Digit Symbol Substitution Test (DSST, standard deviation (SD)=16.16), Stroop Interference Score (SD=10.98), and Rey Auditory Verbal Learning Test (RAVLT, SD=3.27). 26% of participants reported a long-term pattern of low physical activity over 25 years. Compared to more active participants, long-term patterns of low physical activity were associated with increased likelihood of significant poor cognitive performance (<1 SD below the mean) on DSST (inactive: 19% vs active: 15%, OR=1.67, 95% CI 1.30–2.13) and Stroop (inactive: 18% vs active: 11%, OR=1.47, 95% CI 1.15–1.88) but not on RAVLT, after adjusting for age, race, sex, education, smoking, body mass index, and hypertension. For those with very-low activity patterns (long-term pattern of physical activity scores <50 exercise units, 2% of participants), effects were even more pronounced (DSST: OR=2.52, 95% CI 1.34–4.75; Stroop: OR=2.24, 95% CI 1.21–4.14). Beginning in early adulthood, long-term patterns of low physical activity over 25 years were associated with worse mid-life executive function and processing speed. Future prevention strategies should focus on increasing physical activity across the life course.