BACKGROUND: Emerging research found air pollution may be associated with incident Alzheimer's disease (AD) and other dementias. However, few studies have examined these associations at the global scale. This study aimed to assess the dynamic associations between ambient air pollution and the burden of AD and other dementias worldwide. METHODS: This study synthesised 149 countries/territories between 1990 and 2019. These data include age-standardised mortality rate (ASMR) and disability-adjusted life-years (DALYs) of AD and other dementias, ambient air pollution (fine particulate matter [PM RESULTS: During 1990-2019, the global ASMR, DALYs and O CONCLUSIONS: The burden of dementia is expected to increase globally, given the continuously expansion of the ageing population. Air pollution was found to be significantly associated with a higher burden of AD and dementia. As a persistent challenge in urban cities, air pollution demands strict regulatory control.