Critical Values of Daily Sedentary Time and Its Longitudinal Association with Mild Cognitive Impairment Considering APOE ε4: A Prospective Cohort Study

Background

Long sedentary time and physical inactivity are negatively related to cognition, but the cut-off value remains unclear, and apolipoprotein E polymorphism ε4 (APOE ε4) is a known genetic risk factor of mild cognitive impairment (MCI).

Objectives

To explore longitudinal association of sedentary time and MCI, and to identify a cutoff value that increases the risk of developing MCI, taking into account APOE ε4 stratification and its interactions.

Design

A prospective cohort study.

Setting

Population-based study

Participants

We included 4932 older adults from Tianjin Elderly Nutrition and Cognition (TENC) cohort study recruited from March 2018 to June 2021 with 3.11 years of median follow-up time.

Measurements

The primary outcome was newly diagnosed MCI, which was diagnosed by a modified version of the Petersen’s criteria. The information of sedentary time (hours/day) and physical activity (MET-h/week) were obtained by questionnaire. Cox proportional hazard regression models and restricted spline curve were conducted.

Results

A total of 4932 participants were included (mean [SD] age, 67.85 [4.96] years; 2627 female [53.3%] and 2305 male [46.7%]), 740 newly onset MCI patients were identified. Longer sedentary time was associated with higher risk of MCI for all participants (HR:1.069, 95%CI: 1.034, 1.105), especially in APOE ε4 non-carriers (HR:1.083, 95%CI: 1.045, 1.123) whether adjusted potential confounders. Sedentary time had synergistic interactions with APOE ε4 (β:1.503, 95%CI: 1.163, 1.942) and physical activities (β: 1.495, 95%CI: 1.210, 1.846). Restricted spline curve showed a cut-off value of 3.03 hours/day.

Conclusions

Long sedentary time (≥3.03 hours/day) could increase MCI risk, especially in APOE ε4 non-carriers, people with higher PA, aged 65 and above.