Leisure-time physical activity, cardiorespiratory fitness, and cognitive decline in middle-aged and older adults - The ELSA-Brasil study

Objectives: Dementia is a fast-growing public health problem. This study examined the association of physical activity and estimated cardiorespiratory fitness (eCRF) with the risk of cognitive impairment. Study design: Multicentric, prospective cohort study. Methods: We analyzed 10,121 participants of the ELSA-Brasil study. We assessed leisure-time physical activity using the long version of the IPAQ questionnaire and defined moderate-to-vigorous physical activity (MVPA) per week. We applied a non-exercise prediction equation to estimate eCRF and classified participants as unfit (lowest tertile) and fit. Leisure-time MVPA and eCRF were measured at baseline and follow-up. Incident cognitive impairment was based on memory, language, and executive function assessed at baseline and follow-up. Results: During a median of 8.1 (7.8-8.5) years of follow-up, we identified 396 (3.9 %) incident cases of cognitive impairment. There was an inverse, non-linear association between the incidence of cognitive impairment and both leisure time MVPA and eCRF. Low eCRF (IRR: 1.29; 95%CI: 1.02, 1.64) and low MVPA (IRR: 1.40; 1.09, 1.82) were independently associated with an increased incidence. Increasing 1 MET in eCRF from baseline to follow-up visit was associated with a lower incidence of cognitive impairment (IRR: 0.80; 95%CI: 0.71, 0.91), while a decrease of 13.7 min per day in leisure time MVPA is associated with an increased incidence (IRR: 1.16; 95%CI: 1.01, 1.33) of cognitive impairment. These associations remained statistically significant in adults under 65 but not in older adults. Conclusion: Low eCRF and leisure time MVPA are strong and independent predictors of incident cognitive impairment especially in middle-aged adults.