How many people are living with Alzheimer’s disease or another form of dementia? About 44 million, according to a new analysis that looked at Alzheimer’s in 195 countries around the globe.

That’s more than double the number of cases of Alzheimer’s there were in 1990, according to the report. The increase may largely be a result of a growing population around the world that is living to older ages, the authors say.

The findings, published in Lancet Neurology, relied on data from medical registries, death reports, surveys, medical studies and other sources. The researchers found that there were some 20.2 million cases of dementia in 1990. That number rose to 43.8 million by 2016; 27 million of those cases were in women, and 16. 8 million in men.

Turkey had the highest prevalence of dementia among older men and women, followed by Brazil. Nigeria and Ghana had the lowest prevalence.

The analysis also noted four risk factors that evidence shows have a causal link to Alzheimer’s disease:

*A high body mass index. Numerous studies suggest that being overweight or obese at midlife is tied to an increased risk of Alzheimer’s disease.

* A high level of fasting blood sugars. High blood glucose levels are linked to diabetes, which is also a risk factor for Alzheimer’s disease.

* Smoking. People who are smokers are at increased risk of developing Alzheimer’s disease and other forms of dementia. Smoking harms the circulatory system, including the blood vessels that nourish the brain.

* Drinking lots of sugary beverages. Sugar-sweetened sodas are also tied to obesity, which is a risk factor for Alzheimer’s disease. But even after factoring in body weight, sugary drinks were tied to an increase in the risk of dementia.

Dementia is now the fifth leading cause of death around the world, accounting for an estimated 2.4 million deaths each year. Dementia is the second most common cause of death among people aged 70 and older, after heart disease.

Estimates of the number of people living with Alzheimer’s disease remain estimates, because reporting varies from country to country and it is hard to get exact numbers. But in general, experts say that some 40 million to 50 million people are thought to be living with Alzheimer’s disease worldwide. Over 5 million of those are living in the United States, according to various estimates.

By 2050, the number of people living with dementia could increase to around 100 million worldwide, the authors say.

The rising burden of Alzheimer’s around the world underscores the urgent need to find new and better treatments for the disease, while better defining brain-healthy habits and researching the origin of the disease to avoid it all together. Research remains critical to understanding why the disease arises, in the hopes of one day finding a cure.

By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.

Source: GBD 2016 Dementia Collaborators: “Global, Regional, and National Burden of Alzheimer’s Disease and Other Dementias, 1990 to 2016: A Systematic Analysis for the Global Burden of Disease Study 2016.” The Lancet Neurology Nov. 26, 2018