Seniors in These South Dakota Counties Have the Highest Alzheimer's Rates

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Seniors in these South Dakota counties have the highest Alzheimer's rates

An estimated 16,500 people in South Dakota over age 65 have Alzheimer's, according to estimates released by the Alzheimer's Association in 2023.

Alzheimer's disease afflicts an estimated 6.7 million Americans, and that number is only growing. Medical professionals believe the volume of diagnoses could double by 2060 if there isn't a breakthrough in prevention—or a cure.

For the first time, the Alzheimer's Association released estimates on Alzheimer's prevalence in each state and county. Researchers hope these figures will help regional public health officials better treat Alzheimer's patients, develop localized care plans, and budget for care—particularly as new treatments come at a cost.

Alzheimer's is the most common form of dementia and is among the top 10 causes of death in the U.S. These deaths are increasing as fatality rates from other health-related causes, including heart disease and stroke, are on the decline. With Alzheimer's, the brain shrinks, brain cells die, and peoples' memory and language centers fail. As the disease advances, the loss of brain function leads to dehydration, malnutrition, infection, and ultimately death.

Developing a cure or effective treatment has been slow, as medical professionals still don't know what causes Alzheimer's. But earlier this year, the Food and Drug Administration fully greenlit the first drug proven to effectively treat the disease: lecanemab (sold under the brand name Leqembi), created by Eisai Inc. and Biogen. Earlier treatments only addressed symptoms of Alzheimer's, while lecanemab treats the early stages of the disease itself and slows its progression.

The drug costs $26,500 annually and is partially covered by Medicare if a patient's medical team participates in a registry to track the drug's outcomes. Those high costs could keep the treatment out of reach for low-income Americans, who already have higher odds of developing Alzheimer's, studies have shown.

Nearly all Alzheimer's patients are on government insurance, and estimates show that Medicare could spend $2 billion to $5 billion annually on lecanemab and related care. That pales in comparison to the $345 billion that Alzheimer's and other dementias cost in 2023, including nursing home stays, symptom management medications, and other care for those with the disease. Without medical advancements, the Alzheimer's Association expects those costs could rise to nearly $1 trillion by 2050.

If lecanemab and similar drugs can slow progression in even half of mild Alzheimer's patients, one study from the University of Chicago estimates Americans would save $212 billion to over $1 trillion in care-related costs over the next decade.

Having a treatment to slow the progression of Alzheimer's also creates more urgency to diagnose the disease sooner to retain more brain function. Warning signs for the disease include disruptive memory loss, difficulty with familiar tasks, worsening judgment, and changes in mood and personality.

The U.S. has a shortage of specialists in elder and memory-related medicine and nurses providing care at nursing homes and assisted-living facilities. In regions with high rates of Alzheimer's, these shortages could be catastrophic within the current models of care.

Stacker mapped states by the share of the population over age 65 that is estimated to have Alzheimer's disease, using data released by the Alzheimer's Association in July 2023. As a part of the national analysis, Stacker also took a closer look at South Dakota and ranked the counties within it by their estimated Alzheimer's prevalence.

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Alzheimer's rates by state

State and detailed county-level estimates show vast disparities in the prevalence of Alzheimer's disease based on racial and socioeconomic factors. Older Americans, women, Black and Hispanic Americans, and those with lower education levels are at higher risk for developing Alzheimer's dementia, according to data from the Chicago Health and Aging Project, on which these estimates were based.

The East and Southeast regions of the U.S. were estimated to have the highest prevalence of Alzheimer's, particularly Maryland, New York, Florida, Mississippi, and Louisiana. In Maryland, nearly 30% of residents are Black, and a slightly higher share of the population is 85 and older compared to national numbers—substantial risk factors that earn it the #1 spot.

In addition to a high prevalence of the disease, Mississippi has the highest Alzheimer's mortality rate, largely due to having the worst-quality health care system in the country, Time reported.

Some of the most afflicted counties are home to Black and Hispanic populations in the South, low-income populations in Appalachia, and older adults in Florida, according to Time. Other studies have found that people in rural areas tend to be underdiagnosed or diagnosed in later stages of dementia, delaying or preventing potential treatments.

Read on to see where in South Dakota has the highest prevalence of Alzheimer's, ranked by the share of the 65 and over population estimated to have the disease. Initial ties were broken by the number of people estimated to have Alzheimer's, but some ties may remain.

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#50. Butte County

- Share of 65+ population with Alzheimer's: 10.0%
- Number of 65+ population with Alzheimer's: 200 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#49. Union County

- Share of 65+ population with Alzheimer's: 10.0%
- Number of 65+ population with Alzheimer's: 300 people
*These are estimates; actual values have a 95% likelihood of being within 0.5 percentage points of the estimate.

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#48. Ziebach County

- Share of 65+ population with Alzheimer's: 10.1%
- Number of 65+ population with Alzheimer's: Not available
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#47. Stanley County

- Share of 65+ population with Alzheimer's: 10.1%
- Number of 65+ population with Alzheimer's: 100 people
*These are estimates; actual values have a 95% likelihood of being within 0.5 percentage points of the estimate.

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#46. Sanborn County

- Share of 65+ population with Alzheimer's: 10.2%
- Number of 65+ population with Alzheimer's: Not available
*These are estimates; actual values have a 95% likelihood of being within 0.5 percentage points—or 50 people—of the estimate.

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#45. Brookings County

- Share of 65+ population with Alzheimer's: 10.2%
- Number of 65+ population with Alzheimer's: 500 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points—or 50 people—of the estimate.

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#44. Clay County

- Share of 65+ population with Alzheimer's: 10.3%
- Number of 65+ population with Alzheimer's: 200 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#43. Moody County

- Share of 65+ population with Alzheimer's: 10.5%
- Number of 65+ population with Alzheimer's: 100 people
*These are estimates; actual values have a 95% likelihood of being within 0.5 percentage points of the estimate.

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#42. Hughes County

- Share of 65+ population with Alzheimer's: 10.5%
- Number of 65+ population with Alzheimer's: 300 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#41. Harding County

- Share of 65+ population with Alzheimer's: 10.6%
- Number of 65+ population with Alzheimer's: Not available
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#40. Grant County

- Share of 65+ population with Alzheimer's: 10.7%
- Number of 65+ population with Alzheimer's: 200 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#38. Jones County (tie)

- Share of 65+ population with Alzheimer's: 10.8%
- Number of 65+ population with Alzheimer's: Not available
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#38. Sully County (tie)

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#37. Marshall County

- Share of 65+ population with Alzheimer's: 10.8%
- Number of 65+ population with Alzheimer's: 100 people
*These are estimates; actual values have a 95% likelihood of being within 0.5 percentage points of the estimate.

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#36. Clark County

- Share of 65+ population with Alzheimer's: 11.0%
- Number of 65+ population with Alzheimer's: 100 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#34. Deuel County (tie)

- Share of 65+ population with Alzheimer's: 11.1%
- Number of 65+ population with Alzheimer's: 100 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#34. McCook County (tie)

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#33. Roberts County

- Share of 65+ population with Alzheimer's: 11.1%
- Number of 65+ population with Alzheimer's: 200 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#32. Jackson County

- Share of 65+ population with Alzheimer's: 11.2%
- Number of 65+ population with Alzheimer's: 100 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points—or 50 people—of the estimate.

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#31. Yankton County

- Share of 65+ population with Alzheimer's: 11.2%
- Number of 65+ population with Alzheimer's: 500 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#30. Codington County

- Share of 65+ population with Alzheimer's: 11.2%
- Number of 65+ population with Alzheimer's: 600 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#29. Bennett County

- Share of 65+ population with Alzheimer's: 11.4%
- Number of 65+ population with Alzheimer's: 100 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#28. Aurora County

- Share of 65+ population with Alzheimer's: 11.5%
- Number of 65+ population with Alzheimer's: 100 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#27. Beadle County

- Share of 65+ population with Alzheimer's: 11.5%
- Number of 65+ population with Alzheimer's: 400 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#26. Brule County

- Share of 65+ population with Alzheimer's: 11.6%
- Number of 65+ population with Alzheimer's: 100 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#25. Turner County

- Share of 65+ population with Alzheimer's: 11.6%
- Number of 65+ population with Alzheimer's: 200 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#24. Brown County

- Share of 65+ population with Alzheimer's: 11.6%
- Number of 65+ population with Alzheimer's: 800 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points—or 50 people—of the estimate.

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#21. Haakon County (tie)

- Share of 65+ population with Alzheimer's: 11.7%
- Number of 65+ population with Alzheimer's: 100 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#21. Hamlin County (tie)

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#21. Kingsbury County (tie)

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#20. Day County

- Share of 65+ population with Alzheimer's: 11.7%
- Number of 65+ population with Alzheimer's: 200 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#19. Edmunds County

- Share of 65+ population with Alzheimer's: 11.8%
- Number of 65+ population with Alzheimer's: 100 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#18. Potter County

- Share of 65+ population with Alzheimer's: 11.9%
- Number of 65+ population with Alzheimer's: 100 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#15. Charles Mix County (tie)

- Share of 65+ population with Alzheimer's: 11.9%
- Number of 65+ population with Alzheimer's: 200 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#15. Spink County (tie)

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#15. Walworth County (tie)

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#12. Gregory County (tie)

- Share of 65+ population with Alzheimer's: 12.0%
- Number of 65+ population with Alzheimer's: 100 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#12. Jerauld County (tie)

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#12. Miner County (tie)

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#11. Tripp County

- Share of 65+ population with Alzheimer's: 12.1%
- Number of 65+ population with Alzheimer's: 200 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points—or 50 people—of the estimate.

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#10. Davison County

- Share of 65+ population with Alzheimer's: 12.1%
- Number of 65+ population with Alzheimer's: 500 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#9. Perkins County

- Share of 65+ population with Alzheimer's: 12.2%
- Number of 65+ population with Alzheimer's: 100 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#8. Hyde County

- Share of 65+ population with Alzheimer's: 12.3%
- Number of 65+ population with Alzheimer's: Not available
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#6. Douglas County (tie)

- Share of 65+ population with Alzheimer's: 12.3%
- Number of 65+ population with Alzheimer's: 100 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#6. Faulk County (tie)

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#5. Bon Homme County

- Share of 65+ population with Alzheimer's: 12.6%
- Number of 65+ population with Alzheimer's: 200 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#4. Campbell County

- Share of 65+ population with Alzheimer's: 12.9%
- Number of 65+ population with Alzheimer's: 100 people
*These are estimates; actual values have a 95% likelihood of being within 0.7 percentage points of the estimate.

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#3. Hutchinson County

- Share of 65+ population with Alzheimer's: 13.2%
- Number of 65+ population with Alzheimer's: 200 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.

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#1. Hand County (tie)

- Share of 65+ population with Alzheimer's: 13.5%
- Number of 65+ population with Alzheimer's: 100 people
*These are estimates; actual values have a 95% likelihood of being within 0.6 percentage points of the estimate.