Impact of physical activity intensity on longitudinal trajectories of cognitive function and depressive symptoms in middle-aged and older Chinese adults: Eight-year prospective study

Background: Little is known about how longitudinal trajectories of cognitive function and depressive symptoms are impacted by varying levels of physical activity (PA) intensity. Method: The data were from the China Health and Retirement Longitudinal Study, a nationally representative household study of the Chinese population aged 45 years and older. The sample included 5025 middle-aged and older adults (mean age = 57) who self-reported their cognitive function, depressive symptoms, and PA intensity (vigorous PA, moderate PA, and light PA) every two years from 2011 to 2018. Result: On average, every 2 years, cognitive function decreased by 0.17 points (95 % CI: [−0.22, −0.12], P < 0.05), while depressive symptoms increased by 0.23 points (95 % CI: [0.19,0.27], P < 0.001). Middle-aged and older adults who reported a minimum of 6 days/week frequency of moderate PA (β = 0.14, 95 % CI:[0.01,0.27]) had lower reduction of cognitive function compared to people with none moderate PA but not vigorous PA (β = 0.04, 95 % CI:[−0.11,0.19]) and light PA (β = 0.06, 95 % CI:[−0.09,0.22]). The increase in depressive symptoms was significantly slower among middle-aged and older adults with a minimum of 6 days/week light PA (β = −0.02, 95 % CI:[−0.03,-0.002]). Conclusion: A minimum of 6 days of moderate PA a week was associated with a slower reduction in cognitive function and a minimum of 6 days of light PA a week was linked to a delayed increase in depressive symptoms. In middle-aged and older adults, a tailored PA intensity may be more beneficial in achieving the maximum improvement in cognitive function and mental health.