Abstract
OBJECTIVE: To investigate the relationship between obesity and cognitive impairment among older adults using body mass index (BMI) and weight-adjusted waist circumference index (WWI). METHODS: Drawing on the data from the Chinese Longitudinal Healthy Longevity Survey database spanning from 2011 to 2018, the study employed Cox regression analysis and the restricted cubic spline method to examine the relationship between BMI, WWI, and cognitive impairment. RESULTS: A total of 2546 subjects were included in this study. According to BMI, lean was a risk factor for cognitive impairment in older adults (HR = 1.347, 95%CI:1.011 ~ 1.795), overweight (HR = 0.446, 95%CI:0.35 ~ 0.568) and obesity (HR = 0.225, 95%CI:0.161 ~ 0.314) was a protective factor for cognitive impairment in the older adults. According to the classification of WWI, high WWI was a risk factor for cognitive impairment in older adults (HR = 2.064, 95%CI:1.731 ~ 2.461). The restricted cubic spline showed that when WWI > 11 cm/[Formula: see text], the risk of cognitive impairment increased with the increase of WWI. The comprehensive body weight phenotype constructed by BMI and WWI showed that the older adults with lean combined with high WWI were found to have the highest risk of cognitive impairment (HR = 1.542, 95%CI:1.087–2.187), and obesity combined with low WWI had the largest protective effect on cognitive function in the older adults by(HR = 0.108, 95%CI: 0.062 ~ 0.186). CONCLUSION: Maintaining an appropriate level of overweight or even a state of obesity can contribute to the preservation of cognitive health in older adults. This factor holds significant importance as it is a preventive measure against the onset of cognitive impairment.