Yuma County has Arizona's highest level of Alzheimer's disease. What about your county?

Yuma County has the highest prevalence of Alzheimer's disease among Arizonans over the age of 65 and Coconino County has the lowest, new county-level estimates say.

The estimates of Alzheimer's disease prevalence in all 3,142 U.S. counties were shared Monday at the Alzheimer’s Association International Conference in Amsterdam . The data analysis, conducted by researchers at Rush University Medical Center in Chicago, was released in the Alzheimer's Association's journal on the same day.

Officials with the nonprofit Alzheimer's Association say the data is the first to narrow Alzheimer's prevalence down to specific counties, offering a more accurate look at areas that need the most services for people with dementia such as home health aides, neurologists and geriatricians. The researchers estimate that about 151,500 Arizonans ages 65 and older have Alzheimer's disease, which works out to one in nine older Arizonans.

The highest prevalence of Alzheimer's disease among older Arizonans is in Yuma County, where 13.3% of seniors have Alzheimer's, closely followed by Santa Cruz and Greenlee counties, where 13.2% of older county residents have Alzheimer's disease, the researchers estimated.

"We've been needing this data for a very long time. I mean, think about our public health response. If you don't really know the numbers of people being impacted, it's very hard to figure out what you need to build and where you need to build it," said Kinsey McManus, program director for the Desert Southwest chapter of the Alzheimer's Association. "When we look at counties like Yuma, we are woefully understaffed compared to the realities of the situation."

In Maricopa County, which is Arizona's most populated county, about 81,000 seniors or 11.1% of the population of those 65 and older has Alzheimer's disease, according to the researchers, who say they based their estimates on cognitive and demographic characteristics using the Chicago Health and Aging Project and the National Center for Health Statistics 2020 population estimates.

Older Blacks, Hispanics more likely to be affected than others

The county-specific information is particularly important as the local Alzheimer's Association is working with the Arizona Department of Health Services on establishing a strategic statewide Alzheimer's and dementia plan, McManus said. Previously, the association had been using a "rough back-of-the envelope" estimate of where people with Alzheimer's in Arizona were concentrated, and the added level of precision is crucial when it comes to thinking about where to set up and emphasize services, she said.

In general, researchers found that senior citizens in southern Arizona counties had a higher prevalence of Alzheimer's disease than older residents of the state's northern counties. The lowest percentage of Alzheimer's disease among those 65 and older in Arizona was in Coconino County. Seniors in Apache, Navajo and Yavapai counties also had a prevalence that was lower than the state average.

"Some of our southern counties have higher percentages of Hispanic/Latino populations and we know that Hispanic whites have a one and a half times greater rate of Alzheimer's and dementia compared to non-Hispanic whites," McManus said. "I think that's a critical piece in part of this. ... There are counties with much higher percentages over 65 that are not seeing as high a percentage of people with Alzheimer's."

In Yavapai County, for example 35% of the population is over 65, while in Yuma County it's 20%, McManus said.

"So you are talking a big difference in numbers but at the same time, there is not the degree of diversity in Yavapai County as Yuma as a border county," she said. "We're talking about populations that have much higher risks of disease."

The researchers said older Black people are about twice as likely to have Alzheimer’s or other forms of dementia as older white people, and older Hispanics are about one and one-half times as likely to have Alzheimer’s or other dementias as older people.

At least part of the explanation for the racial disparities is the generally poorer health outcomes for people of color who have a history of marginalization from the health care system as well as generally higher rates of poverty than the white population. While the biggest risk factor for Alzheimer's disease is age, some studies have found other factors put people at higher risk, including high blood pressure, obesity and a lack of exercise.

"We talk about heart health being important for brain health, so in a community that struggles more with heart health, it's not surprising to see some higher rates of (Alzheimer's) disease," McManus said.

Overall, the study found that the east and southeastern areas of the U.S. had the highest prevalence of Alzheimer's disease in older residents, with the highest percentages in Maryland, New York and Mississippi. Higher percentages of older people and Black and Hispanic residents in those regions could be part of the reason, the authors wrote.

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Data on Indigenous people with Alzheimer's has limitations

McManus said she was surprised by the lower prevalence of Alzheimer's disease in Navajo and Apache counties, which have a high concentration of Indigenous residents. She said the Alzheimer's Association plans to look at that population more closely to make sure that the county-level estimates accurately reflects what is happening with Alzheimer's disease and dementia in those northern Arizona counties.

Indeed, one limitation to the county-specific data is for estimates of prevalence among Native Americans and Alaska Natives, the Chicago researchers wrote, explaining that their estimates focused on the Black, Hispanic and white populations. The authors noted a 2016 study by researchers at the University of California, San Francisco and Kaiser Permanente that looked at six racial/ethic groups over 14 years and found that indigenous Americans had a higher rate of dementia than the white population.

While Arizona was not one of the states with the highest prevalence of Alzheimer's disease, Maricopa County has the third-largest county population of people with Alzheimer's, behind Los Angeles County in California and Cook County in Illinois, the researchers found.

Also, the data in the county-level estimates was from 2020 and based on previous projections, Arizona is expected to see a huge increase in the number of residents living with Alzheimer's disease between 2020 and 2025. The west and southwest regions of the U.S. are expected to experience the largest percentage increase in people living with Alzheimer’s during those five years, according to the Alzheimer's Association.

“This information, in addition to raising awareness of the Alzheimer’s crisis in specific communities, may help public health programs better allocate funding, staffing and other resources for caring for people with Alzheimer’s and all other dementia," Rush Medical College professor Kumar Rajan, one of the study's authors, said in a written statement. "Alzheimer’s dementia is a multifactorial disease involving several risk characteristics that interact with demographic risk factors and ultimately contribute to the prevalence.”

Arizona does not have enough supports for people with Alzheimer's disease, which is a problem nationwide, McManus said.

"As a state there's a lot of growth that needs to happen with specialists, with home health and personal care aides," she said. "The reality is that without a cure, this disease is progressive and it becomes increasingly more difficult to care for someone who has it. It does require 24/7 care at a certain point and we just do not have the staffing in the field to really serve the needs of the community."

Reach health care reporter Stephanie Innes at Stephanie.Innes@gannett.com or at 602-444-8369. Follow her on Twitter @stephanieinnes.

This article originally appeared on Arizona Republic: Yuma County seniors may have the highest percent of Alzheimer's in AZ