The Association Between the Weight-Adjusted Waist Index and Dementia Risk in Older Adults: A Prospective Cohort Study

<b>Background/Objectives:</b> The weight-adjusted waist index (WWI), a novel measure of abdominal obesity independent of overall weight, has shown promise in assessing health risks. However, its relationship with dementia remains unclear. This study investigates the association between the WWI and dementia risk in British older adults. <b>Methods</b>: Employing data from the United Kingdom Biobank, we conducted a prospective cohort study focusing on 155,683 elderly participants. Multivariable logistic regression models were employed to investigate the linear association between the WWI and all-cause dementia. Restricted cubic spline analysis was used to evaluate non-linear relationships, while subgroup analyses and interaction tests were performed to examine the stability of findings across different populations. <b>Results</b>: Among participants (mean age: 63.2 years; 52.2% male), 3211 dementia cases were identified during 13.1 years of follow-up (2.06% prevalence). The analysis revealed a significant inverse relationship between the WWI and dementia risk. In fully adjusted models, higher WWI was associated with a reduced risk of dementia (β = -0.274, <i>p</i> < 0.001). When the WWI was categorized into quartiles, participants in the highest quartile exhibited a 47% lower risk of dementia compared to those in the lowest quartile. This inverse association was particularly pronounced among non-current smokers (<i>p</i> < 0.05 for interaction). Restricted cubic spline analysis confirmed a non-linear relationship, with the protective effect of the WWI becoming more evident at higher values. <b>Conclusions</b>: The WWI is inversely associated with dementia risk in British older adults. These findings reveal that the WWI may serve as a potential predictor for dementia risk, highlighting its potential in risk stratification and prevention strategies.