Age‐dependent relationship between body mass index and cognitive impairment: A cross‐sectional study based on the rural population aged 40 years old and above in Xi'an, China

The relationship between BMI and cognitive impairment was affected by age. No significant association was found in the middle-aged population of 40-59 years old; while there may be a nonlinear association in the elderly population over 60 years old. Specifically, with BMI = 25 kg/m2 as the boundary, as BMI decreased, the risk of cognitive impairment gradually increased; and as BMI further increased, the risk of cognitive impairment did not change significantly even if it reached the obesity level.