The number of adults (aged 40 years and older) living with dementia worldwide is expected to nearly triple, from an estimated 57 million in 2019 to 153 million in 2050, due primarily to population growth and population aging. The Global Burden of Disease Study, published in The Lancet Public Health is the first to provide forecasting estimates for 204 countries worldwide.

The study also looks at four risk factors for dementia - smoking, obesity, high blood sugar and low education - and highlights the impact they will have on future trends. For example, improvements in global education access are projected to reduce dementia prevalence by 6.2 million cases worldwide by 2050. But this will be countered by anticipated trends in obesity, high blood sugar and smoking, which are expected to result in an additional 6.8 million dementia cases.

The study highlights the urgent need to roll out locally tailored interventions that reduce risk factor exposure, alongside research to discover effective disease-modifying treatments and new modifiable risk factors to reduce the future burden of disease.

"Our study offers improved forecasts for dementia on a global scale as well as the country-level, giving policymakers and public health experts new insights to understand the drivers of these increases, based on the best available data", says lead author Emma Nichols from the Institute for Health Metrics and Evaluation at the University of Washington. "These estimates can be used by national governments to make sure resources and support are available for individuals, caregivers, and health systems globally."

She continues, "At the same time, we need to focus more on prevention and control of risk factors before they result in dementia. Even modest advances in preventing dementia or delaying its progression would pay remarkable dividends. To have the greatest impact, we need to reduce exposure to the leading risk factors in each country. For most, this means scaling up locally appropriate, low-cost programs that support healthier diets, more exercise, quitting smoking, and better access to education. And it also means continuing to invest in research to identify effective treatments to stop, slow or prevent dementia."

Dementia is currently the seventh leading cause of death worldwide and one of the major causes of disability and dependency among older people globally - with global costs in 2019 estimated at more than $1 trillion. Although dementia mainly affects older people, it is not an inevitable consequence of aging.

A Lancet Commission published in 2020 suggested that up to 40% of dementia cases could be prevented or delayed if exposure to 12 known risk factors were eliminated - low education, high blood pressure, hearing impairment, smoking, midlife obesity, depression, physical inactivity, diabetes, social isolation, excessive alcohol consumption, head injury and air pollution.

The study was funded by the Bill and Melinda Gates Foundation and Gates Ventures, and conducted by the GBD 2019 Dementia Forecasting Collaborators.