Dementia cases may triple globally by 2050: Study

Unless countries act swiftly to address dementia risk factors, global cases of dementia may triple by 2050, according to a new study published Thursday in the Lancet.

"Our study offers improved forecasts for dementia on a global scale as well as the country-level, giving policy makers and public health experts new insights to understand the drivers of these increases, based on the best available data," lead author Emma Nichols, from the Institute for Health Metrics and Evaluation at the University of Washington, said in a statement.

A new mathematical model used for the study estimates that the global prevalence of dementia could nearly triple by 2050 -- from 57 million to 153 million -- with cases in the U.S. increasing from 5.2 million to 10.5 million.

Dementia is currently the seventh-leading cause of death worldwide, according to the World Health Organization. It contributes to significant disability in older people with associated costs globally reaching $1 trillion U.S. in 2019, the WHO reported.

While there are higher rates of dementia in older individuals, it should not be viewed as a normal part of aging. Many risk factors have been linked to dementia, but researchers focused on four predictive risk factors that can be improved: obesity, smoking, high blood sugar and low education.

The study predicts dementia rates will rise at different rates around the world. High-income Asia Pacific countries are expected to have the smallest increase, while eastern sub-Saharan African countries are expected to have the greatest increase.

"Low- and middle-income countries in particular should implement national policies now that can mitigate dementia risk factors for the future, such as prioritising education and healthy lifestyles," co-author Professor Theo Vos from IHME, University of Washington, said in a statement.

This predictive study does have its limitations, as outlined by the authors. For example, there is a lack of high-quality data from several parts of the world.

In addition, they did not distinguish between the different subtypes of dementia, such as vascular dementia and Alzheimer's dementia, which may have different risk factors.

ABC News' Dr. Alexis Carrington contributed to this report.

Dr. Siobhan Deshauer is an internal medicine specialist and rheumatology fellow at McMaster University, Canada, and a member of the ABC News Medical Unit.