Scientists say dementia cases in the U.S. will rise rapidly in the coming decades

The number of people in the United States who develop dementia each year will double over the next 35 years and will reach approximately one million annually by 2060. new study estimates, and the number of up-to-date cases annually among black Americans will triple.

This raise will be driven primarily by an increasingly aging population, as many Americans are living longer than previous generations. By 2060, some of the youngest baby boomers will be in their 90s, and many millennials will be in their 70s. Older age is the greatest risk factor for dementia. The study found that the enormous majority of dementia risk occurred after age 75, and the risk of dementia became even greater as people reached age 95.

test, published Monday in Nature Medicinefound that adults over the age of 55 have a 42% lifetime risk of developing dementia. That’s significantly higher than previous lifetime risk estimates, which the authors attributed to updated information about Americans’ health and longevity and the fact that the study population was more diverse than the population in previous studies that included mostly white participants.

Some experts said the up-to-date estimates of lifetime risk and the projected raise in annual cases may be too high, but they agreed that dementia cases will rise rapidly in the coming decades.

“Even if the rate is much lower, we will still face a huge raise in the number of people and the family and community burden of dementia due to the sheer raise in the number of older people, both in the United States and around the world,” said Dr. Kenneth Lang, a professor of medicine at the University of Michigan who has studied the risk of dementia and was not involved in the up-to-date study.

Dementia is already causing enormous toll on American families and the country’s health care system. Currently, more than six million Americans suffer from dementia, almost 10 percent of people aged 65 and olderresearch has shown. Experts say dementia causes more than 100,000 deaths in the United States each year and generates more than $600 billion in care and other costs.

If the up-to-date projections are true, about 12 million Americans will have dementia in 2060, said Dr. Josef Coresh, director of the Optimal Aging Institute at Novel York University’s Grossman School of Medicine and leader of the study, which involved about 100 scientists in 10 universities.

The authors and other experts say the study highlights the urgent need to prevent or tardy dementia. Their main recommendations are to improve people’s cardiovascular health through medication and lifestyle changes; raise efforts to prevent and treat strokes, which can lead to dementia; and encourage people to wear hearing aids, which appear to prevent dementia by enabling people to be more socially and cognitively engaged.

“You have to recognize the enormous scale of the problem,” said Alexa Beiser, a professor of biostatistics at the Boston University School of Public Health, who was not involved in the up-to-date study but reviewed it as an independent reviewer for the journal. “It’s huge and it’s not evenly distributed among people,” Dr. Beiser added, noting that the study found a disproportionate risk for Black Americans.

Researchers evaluated data from more than three decades of long-term studies of people’s health in four communities – Maryland, Mississippi, Minnesota and North Carolina. According to Dr. Coresh, about 27 percent of the 15,000 participants were black, mostly from Jackson, Missouri. The authors say the analysis, funded by the National Institutes of Health, focused on black and white participants because there were not many participants from other racial and ethnic groups.

The study estimated that the number of up-to-date cases per year among Black people will raise to about 180,000 in 2060 from about 60,000 in 2020. The main reason for the tripling of up-to-date cases in this population is that the percentage of Black Americans living to the oldest age is growing faster than among white people, Dr. Coresh said.

In the study, black participants also developed dementia at an average age younger than white participants and had a higher lifetime risk of developing the disease.

“I don’t know if we fully understand it, but at least some of the contributing factors are a higher prevalence of vascular risk factors,” Dr. Coresh said, noting that hypertension, diabetes and high cholesterol levels raise the risk of dementia. He said the lower socioeconomic status and education levels of study participants, as well as structural racism that impacted health, may also have played a role.

Predicting dementia risk is complicated for several reasons. The causes of dementia vary and are often not fully understood. Types of dementia also vary and may overlap. The up-to-date analysis, like several other studies, did not attempt to estimate how many people would develop Alzheimer’s disease, the most common type of dementia. This is because many experts believe that the symptoms of Alzheimer’s disease may overlap with vascular dementia and that cardiovascular problems may be the cause of both conditions, Dr. Coresh said.

Several studies conducted in America and around the world have reported the rate of dementia among older adults has declined in recent yearsmost likely due to better treatment of cardiovascular problems and a better educated population, as education can improve brain immunity and overall health.

Experts and authors say the decline doesn’t contradict the up-to-date study because the study estimated the current level of cumulative dementia risk over people’s lives and projected it into the future. It’s possible that positive changes – such as healthier behaviors and better treatments for conditions such as diabetes and stroke – could lower the risk rate at any age in future decades, but the number of up-to-date cases each year will continue to rise from the current figure of 514,000, with due to the growing elderly population, experts say.

“Whether it’s a million or 750,000 people a year, there will be a lot of them, and the longer people live, the more cases of dementia there will be,” said Dr. Beiser, who worked on previous studies different patients for which lower estimates were obtained.

The study also found that women had a higher lifetime risk of dementia than men – 48% compared with 35%. Dr. Coresh said this was primarily because the women in the study lived longer. “The risk of developing dementia before their 95th birthday is higher because more will be closer to their 95th birthday,” he said.

Dr. Langa said other researchers were trying to find out whether there might also be biological differences that raise women’s risk, perhaps “the hormonal environment in the body or even potential genetic differences that might affect women’s brains differently than men’s.” .

Another high-risk group included people with two copies of the APOE4 gene variant, which significantly increases the risk of Alzheimer’s disease and its development at a younger age than people without this variant. In the study, the lifetime risk of dementia for people with two copies of APOE4 was 59%, compared with a lifetime risk of 48% for people with one copy and 39% for people without the variant.

The analysis used health data from the Atherosclerosis Risk in Communities study (known as ARIC), which included people aged 55 and older from 1987 to 2020.

The researchers used several methods to determine if and when participants developed dementia. About a quarter of the cases were diagnosed through in-person neuropsychological testing, while others were identified through hospital records, death certificates or telephone interviews. According to experts, each method has limitations that may lead to overestimation or underestimation of the true number of dementia patients.

The study found that by age 75, the risk of dementia was about 4 percent; at age 85 it was 20 percent; and at 95 it was 42 percent. The researchers applied the risk percentage to census population projections to estimate future annual dementia diagnoses.

To reduce the risk of developing dementia, experts and study authors emphasized taking steps to eliminate known risk factors such as diabetes, high blood pressure and hearing loss. A recent report by Lancet Commission on Dementia listed 14 risk factors that can be improved and concluded that “half of the risk of dementia is preventable and it is never too early or too delayed to address the risk of dementia,” Dr. Coresh said.

Experts recommended such steps instead of searching for up-to-date Alzheimer’s drugs, which appear to be able to only moderately tardy cognitive decline in the early stages of the disease and which carry safety risks.

“Because of their relatively restricted effectiveness, I don’t think we’ll be very successful in reducing lifetime risk this way,” Dr. Langa said of the up-to-date drugs. “I really think that some of these public health and lifestyle interventions that seem to improve overall health and reduce the risk of dementia will allow us to get more bang for our buck.”