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  • New research finds the prevalence of dementia is dropping for people over age 65 in the U.S.
  • Researchers found in 2000, the age-adjusted prevalence of dementia for those over 65 was a little over 12%. However, by 2016 it had dropped to 8.5%, a drop of nearly one-third.
  • For men as a whole, dementia rates dropped from slightly over 10%, to just 7% of the population.

New research from the RAND Corporation finds the prevalence of dementia in the U.S. is declining in the over-65 age group; dropping from 12% of the population in 2000 to just over 8% in 2016.

This is welcome news as Americans are living longer, raising the risk of developing dementia as they age.

While the prevalence of dementia is expected to drop in older adults, overall cases may still rise as more people live to age 65 and older.

According to the Centers for Disease Control and Prevention (CDC), among people at least 65 years of age, there were an estimated 5 million adults with dementia in 2014. That number is projected to be nearly 14 million by 2060.

The new RAND study employed a unique model that assessed cognitive status based on a broad set of cognitive measures gathered from over 21,000 people who participated in the national Health and Retirement Study (HRS), a large, population-representative survey that has been sent out for more than twenty years.

Researchers found in 2000, the age-adjusted prevalence of dementia for those over 65 was a little over 12% meaning just over 1 in 10 adults had dementia.

However, by 2016 it had dropped to 8.5%, a drop of nearly one-third.

The findings indicate that the rate of decline was particularly rapid between 2000 and 2004.

The gap in dementia rates between Black and white men narrowed over time, with dementia prevalence decreasing 7 percentage points among Black men.

That is compared to a nearly drop of 3 percentage points among white men.

However, researchers found that women continue to experience higher rates of dementia, although it dropped from 13.6% of the female population to just under 10% during the study period.

For men as a whole, dementia rates dropped from slightly over 10% of the male population, to just 7% of this group.

Lead study author Péter Hudomiet, PhD, an economist at RAND, a nonprofit research organization, told Healthline that reducing health disparities is a “high-level national priority.”

“Prior literature identified large differences in dementia prevalence between population subgroups,” he said. “Women, the less educated, and racial minority individuals had higher chances of living with dementia.”

He noted that prior literature has also identified decreasing trends in dementia in several developed countries in North America and Europe.

“Less is known about how inequalities in dementia changed in recent decades, even whether they have increased or decreased,” said Hudomiet. “Yet this knowledge is vital if public policy is to address these disparities.”

The RAND study found educational attainment was an important factor that statistically contributed to the reduction in dementia, explaining about 40% of the reduction among men and 20% of the reduction for women.

Betsy Mills, PhD, Assistant Director of Aging and Alzheimer’s Prevention at the Alzheimer’s Drug Discovery Foundation (ADDF) said the primary hypothesis regarding this association is related to something called cognitive reserve, which refers to the resiliency of the brain.

“A brain that is highly resilient can remain functional even after some of the brain cells have been damaged because there are other cells that can perform similar tasks as the ones that were lost,” she said.

She said this allows for someone to be cognitively normal even though their brains may contain “a lot of pathology.”

“Learning helps the brain cells to form and maintain connections,” she explained. “The more connections there are, the more redundancy there is in the network, and this redundancy helps make the brain more resilient.”

“These favorable findings were somewhat surprising because health inequalities were reported to have increased in recent decades,” said Hudomiet.

“For example, there is robust evidence that mortality inequalities have increased substantially over the last 30 years in the U.S.,” he continued. “While life expectancies stagnated or even decreased among less educated individuals, they substantially increased among more educated individuals.”

Hudomiet pointed out that inequalities in smoking and obesity have also increased.

“Fortunately, unlike with these health outcomes, we see a narrowing gap in dementia,” he said.

“Our research shows that the prevalence of dementia has decreased in recent decades, and inequalities have narrowed,” said Hudomiet. “This suggests that it is possible to reduce the risk of dementia.”

He added that the study didn’t uncover new behavioral factors that may delay the onset of dementia – but there is evidence in the literature that “proper treatment of hypertension, avoiding tobacco, and being physically, cognitively, and socially active may help reduce the risk of dementia.”

Roberta Brinton, PhD, Director, Center for Innovation in Brain Science at the University of Arizona said it’s because women can start the disease earlier, in mid-life.

She explained that Alzheimer’s disease has a 20-year preclinical phase, and the average age of diagnosis of Alzheimer’s is in the mid-70s, which in this case leads to a woman in her 50s.

Alzheimer’s disease is the most common form of dementia.

Brinton said as women enter menopause it may affect glucose levels, which can impact the brain.

“That’s the math side of it, but more convincingly is the biology side of it,” she said. “That women can experience a shift in the availability of glucose and utilization of glucose as its primary fuel for the brain.”

“The brain is literally a one-fuel organ,” she continued. “Yes, it can use auxiliary fuels under stress and under conditions of starvation, but on the whole it’s a glucose-driven organ.”

Brinton said when there’s a decline in glucose uptake into the brain, and glucose metabolism, this can put the brain at “severe risk” of developing Alzheimer’s disease.

Asked why this is the case for women, Brinton said it may be because estrogen promotes glucose uptake into the brain, glucose metabolism, and ultimately conversion of that glucose into ATP energy.

“And the loss of estrogen can induce a utilization of auxiliary fuels as if the brain was starving,” she added. “Over a long period of time, in certain women, that can lead to adverse outcomes like Alzheimer’s disease.”

New research finds that the prevalence of dementia among people over 65 has declined significantly from 2000 to 2016, with women experiencing a much smaller decline.

Experts say the proper treatment of conditions like high blood pressure, healthy lifestyle changes, and quitting smoking may help reduce our risk of dementia.

They also say learning helps the brain to be more resilient and could help delay symptoms of cognitive decline.