Differential Associations of 6 Adiposity Indices With Dementia in Older Adults: The MIND-China Study

Objectives The cross-sectional association between late-life obesity and dementia is often explained by the obesity paradox. We assessed the potential differential associations of various adiposity indices with dementia and subtypes of dementia in rural Chinese older adults. Design A population-based cross-sectional study. Setting and Participants A total of 5277 participants (age ≥60 years; 57.23% female) who were living in rural communities and were examined in March–September 2018 for MIND-China. Methods We used weight, height, and waist circumference (WC) to calculate 6 adiposity indices: body mass index (BMI), waist-to-height ratio (WHtR), weight-adjusted-waist index (WWI), A Body Shape Index (ABSI), body roundness index (BRI), and Conicity Index (ConI). Dementia, Alzheimer's disease (AD), and vascular dementia (VaD) were clinically diagnosed following the international criteria. Data were analyzed with logistic regression models. Results Of the 5277 participants, 303 were diagnosed with dementia, including 193 with AD and 99 with VaD. The multivariable-adjusted odds ratio (95% CI) of dementia associated with the highest (vs lowest) quintile of adiposity index was 2.32 (1.40–3.85) for WWI, 1.56 (1.03–2.36) for ABSI, and 1.40 (0.92–2.11) for ConI. Similarly, higher levels of these 3 adiposity indices were significantly associated with an increased likelihood of AD, whereas a higher BMI was associated with a decreased likelihood of AD. None of the 6 examined adiposity indices was significantly associated with VaD when adjusting for multiple confounders. Conclusions and Implications The adiposity index WWI is linearly associated with the likelihood of dementia and AD. An increased WWI may be a clinical marker for the dementia syndrome and Alzheimer's dementia.