Worldwide Dementia Rates More Than Doubled Over 26-Year Span

Megan Brooks

December 18, 2018

Rates of dementia worldwide more than doubled from 1990 to 2016, mainly due to population aging, a new report from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2016 Dementia Collaborators indicates. 

"With limited scope for prevention and the absence of an effective disease-modifying treatment, the burden on caregivers and the parts of health-care systems devoted to care of the elderly will continue to increase rapidly," researchers warn.

The report includes data on dementia between 1990 and 2016 are from 195 countries and regions. It was published online November 26 in Lancet Neurology.

Over the 26-year study period, there was only a minor increase of 1.7% in the global age-adjusted prevalence of dementia, from 701 cases per 100,000 population in 1990 to 712 per 100,000 population in 2016, the authors note.

However, due to population aging and growth, the number of people affected by dementia worldwide has more than doubled, from 20.2 million in 1990 to 43.8 million in 2016 — an increase of 117%.

Among those with dementia in 2016, 27 million were women and 16.8 million were men.

The number of deaths due to dementia jumped by 148% between 1990 and 2016. Dementia was the fifth leading cause of death globally in 2016, accounting for 2.4 million deaths.

Overall, 28.8 million disability-adjusted life-years (DALYs) were attributed to dementia; 6.4 million of these could be attributed to four modifiable risk factors: high body mass index (BMI), high fasting plasma glucose, smoking, and a high intake of sugar-sweetened beverages, the report notes.

A Growing Challenge

It's been estimated that by 2050, the number of people living with dementia could be around 100 million. "Tackling this will require training of health professionals, as well as planning and building facilities to cater to increasing numbers [of] individuals with dementia," the authors write.

"Despite the low return on research investment in dementia in the past, the size of the burden and its increasing trend warrant a continued effort to find effective means of intervening. Until such breakthroughs are made, dementia will constitute an increasing challenge to health-care systems across the globe," they note.

Monitoring trends in dementia is difficult, say the researchers, because there is "substantial heterogeneity" in the global literature on how dementia cases and deaths are recorded, "highlighting the need for more consistency in future research."

In an accompanying editorial, Lenore Launer, PhD, of the neuroepidemiology section at the National Institute on Aging, notes that the definition of dementia is "still evolving in research and clinical communities, and this affects how data are entered into administrative databases. From a public health and disease-prevention perspective, too few quality data are available for dementia that fit the complex reality of this devastating public health problem."

Going forward, Launer notes several areas of data collection and interpretation that need strengthening: improving research methods used in data collection and interpretation; developing a consensus about valid coding of dementia for administrative databases; and developing flexible approaches that take into account the variation in place and over time of health and social conditions that may lead to severe cognitive impairment.

The study was supported by the Bill & Melinda Gates Foundation. A complete list of disclosures for the GBD Dementia Collaborators is listed with the original article.

Lancet Neurol. Published online November 26, 2018. Full text, Editorial

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