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Researchers say the incidence rate of dementia has decreased by 13 percent since 1988, most likely due to better health education and changes in lifestyle. Getty Images
  • A recent study shows the incidence rate of dementia in the United States and Europe from 1988 to 2015 declined by 13 percent per decade.
  • If trends continue, this means there could be 15 million fewer people living with dementia in high-income countries by 2040.
  • Experts say the change is likely linked to increased health literacy along with better understanding of modifiable risk factors, such as exercise and diet.
  • Experts stress the need for doctors and patients alike to lower one’s risk for developing dementia by following healthy habits.

A new study shows that the chances of developing dementia have declined over time.

The study, published last week in the journal Neurology, looked at trends in the United States and Europe between 1988 and 2015.

Researchers observed that the incidence rate of dementia has dropped by 13 percent per decade over the past quarter-century.

If these trends continue, they note, there could be as many as 15 million fewer people in high-income countries as well as up to 60 million fewer people worldwide living with dementia by 2040.

The researchers also examined those with an Alzheimer’s disease diagnosis, the most common type of dementia. The likelihood of developing that condition has dropped by 16 percent per decade.

Experts say the findings are a positive sign for the future of dementia research, and may suggest that modern medicine is doing a better job of controlling risk factors that lead to dementia.

“The data are particularly encouraging because the study looked at an extraordinarily large number of people from longitudinal studies conducted in different regions of the world, so the data are especially applicable and trustworthy,” Dr. Jason Krellman, an assistant professor of neuropsychology at Columbia University Medical Center in New York, told Healthline.

It’s important to note that the study’s findings don’t imply that dementia will ever be eradicated.

Dr. Marc Gordon, chief of neurology at Zucker Hillside Hospital in Glen Oaks, New York, told Healthline that the study examined incidence (one’s chance of developing dementia) and not prevalence (the overall percentage of people who have dementia).

“Just because age-related incidence is going down does not mean that there’s not going to be a problem,” he explained.

“The population is getting older, and there are still going to be a lot of people with disease, whether it’s 15 million fewer in 20 years that they projected, or not. It’s still a lot of people with Alzheimer’s disease and other causes of dementia. It’s not to say that this isn’t good news, but it’s not like there’s no problem either,” Gordon said.

While the study’s numbers speak for themselves, the authors didn’t speculate on a specific cause for the decline, noting that “there have been many concurrent changes over time in possible key risk factors.”

Krellman points out that modifiable lifestyle factors, such as exercise, diet, intellectual stimulation, and social interaction, are all known to reduce the risk of developing dementia.

“Patients today are living longer but also healthier lives because of this awareness, and this study is probably reflecting that positive fact,” he said. “In general, the patients we see today are undoubtedly more health conscious and compliant with medical advice than their counterparts from a generation or two ago.”

Krellman also points to a number of developments in the field of dementia research over the past few decades that have aided understanding, although treatment options for someone who already has dementia remain limited.

“We have come to understand much more about the biological mechanisms that underlie the development of Alzheimer’s disease and other conditions that lead to dementia, and we have learned in recent years about the important link between cardiovascular disease and dementia.

“Unfortunately, treatments to delay or slow the progression of dementia are still early in development. Although promising, these treatments are not available yet, which makes staying aware of, and reducing modifiable risk factors, for dementia quite important,” Krellman said.

Another factor to keep in mind is that systemic factors will likely influence who develops dementia.

Krellman notes that poor cardiovascular health and dementia will likely continue to be more common in those with lower levels of education and socioeconomic status due to limited access to quality healthcare.

Twenty years from now, there will still be people living with dementia, but if the study’s projections are accurate, there will still be a significant reduction.

If this happens, Krellman says, the healthcare field could turn its efforts toward continual education about how people can use lifestyle modifications to minimize their risk.

“Maintaining those modifiable risk factors at an optimal level is a different challenge for a 60-year-old than an 85-year-old, so the field would need to learn how to educate and address these factors in older individuals who might have a more difficult time staying active, engaged, and practicing healthy habits because of advancing age,” he said.

It’s also important to recognize that these projections may not be borne out, despite the recent trend.

“I think the study authors do make the point that you can’t necessarily assume that these trends will continue,” Gordon said.

“One other thing to bear in mind is that what we’re seeing in terms of analyzing the rates of dementia is that they’re reflecting things that actually changed 20 years ago — so the changes may have happened 20 years ago, and we’re seeing results now here.

“The good news is it does suggest that there may be things we can do, and raises questions as to what we can do that could affect the incidence of dementia,” Gordon said.

Krellman stresses that dementia isn’t an inevitable side effect of getting older, and that reducing the risk is a job for both doctors and patients.

“The study emphasizes the need for us to work diligently to reduce healthcare disparities so that all people can access quality healthcare and understand the lifestyle habits that reduce dementia risk,” he said.