The global cost of dementia in 2015 was estimated at $818 billion, a 35% increase from $604 billion in 2010. This represents 1.09% of global GDP, with 86% of costs occurring in high-income countries (HICs). Direct medical costs account for a small proportion, while direct social care and informal care contribute similarly. The global cost is expected to reach $1 trillion by 2018. The increase in costs is due to both an increase in the number of people with dementia and higher per capita costs. The study used a societal, prevalence-based approach to estimate costs, with data aggregated by country income level, region, and other factors. The 2015 estimates are based on updated prevalence data and include new studies from various countries. The study also performed sensitivity analyses, showing that the method of quantifying informal care significantly affects total costs. The cost of dementia per person varies widely by country income level, with higher costs in HICs. The report highlights the uneven distribution of dementia costs, with most costs occurring in HICs despite the majority of people with dementia living in lower-middle-income countries (LMICs). The study also forecasts that global dementia costs will reach $2 trillion by 2030. The findings underscore the need for continued research and monitoring of dementia costs and prevalence to improve understanding and management of the disease.The global cost of dementia in 2015 was estimated at $818 billion, a 35% increase from $604 billion in 2010. This represents 1.09% of global GDP, with 86% of costs occurring in high-income countries (HICs). Direct medical costs account for a small proportion, while direct social care and informal care contribute similarly. The global cost is expected to reach $1 trillion by 2018. The increase in costs is due to both an increase in the number of people with dementia and higher per capita costs. The study used a societal, prevalence-based approach to estimate costs, with data aggregated by country income level, region, and other factors. The 2015 estimates are based on updated prevalence data and include new studies from various countries. The study also performed sensitivity analyses, showing that the method of quantifying informal care significantly affects total costs. The cost of dementia per person varies widely by country income level, with higher costs in HICs. The report highlights the uneven distribution of dementia costs, with most costs occurring in HICs despite the majority of people with dementia living in lower-middle-income countries (LMICs). The study also forecasts that global dementia costs will reach $2 trillion by 2030. The findings underscore the need for continued research and monitoring of dementia costs and prevalence to improve understanding and management of the disease.