Socioeconomic inequalities in dementia burden related to high body mass index, 2005–2018: findings from 1.25 million Chinese adults

Background: Dementia has become a major public health concern worldwide, but comprehensive assessments of dementia burden attributable to high body mass index (BMI) in China have not been done. Methods: We used a temporal-spatial Bayesian hierarchical model to estimated BMI levels based on 1.25 million Chinese. We estimated dementia burden attributable to high BMI by age, sex, year, and socioeconomic development in terms of deaths and years of life lost (YLLs) and assessed the effect of population ageing. Findings: The average age-standardised BMI was 24.58 kg/m2 and 24.15 kg/m2 for men and women in 2018, respectively. 12,901 (95% UI, 10,617–15,420) dementia deaths were attributable to high BMI in China in 2018, with 5417 deaths from man and 7421 deaths from woman. The attributable age-standardised YLL rates for dementia increased 27% from 2005 to 2018. The attributable age-standardised mortality rates increased with human development index. People aged 80 years and older had the highest attributable mortality rate, and the rate decreased with decreasing age. Population ageing was an important component of the increase in dementia death. Interpretation: The rapid increase and large inequality highlighted the urgent need for evidence-based policies and interventions. We therefore call for establishing stronger anti-dementia strategies to promote the healthy ageing. Funding: China National Key Research and Development Program, China National Science & Technology Pillar Program, and National Health Commission of the People's Republic of China.