With new medications on the market or in the works for Alzheimer’s disease and other kinds of dementia, a new study suggests that getting the diagnosis needed to access these new treatments may depend on where you live.
The percentage of people who get a new dementia diagnosis each year varies a lot across regions of the U.S., the study finds.
And the differences between regions of the country are even larger for people on the young end of the dementia-risk age range, ages 66 to 74, and for those who are Black or Hispanic.
In fact, the same person would have as much as twice the chance of getting a dementia diagnosis in some areas of the U.S. as in others, the study shows. The findings suggest that the chance of being diagnosed may be more about the health system than about individual factors that affect dementia risk.
The new study focuses on regional differences in “diagnostic intensity” of dementia – the kind of difference that exists even after all kinds of dementia risk factors and regional differences in population and health care are taken into account.
Performed by a team based at the University of Michigan, it’s published in Alzheimer's & Dementia: The Journal of the Alzheimer's Association.
Julie Bynum, M.D., M.P.H. and her colleagues at U-M and the Dartmouth College Geisel School of Medicine did the study using data from the records of 4.8 million people who were covered by traditional Medicare and over the age of 66 in 2019.
They note that while nearly 7 million Americans currently have a diagnosis of dementia, millions more likely have symptoms but no formal diagnosis.
The study looked at diagnoses within each of 306 hospital referral regions developed for the Dartmouth Atlas of Health Care and used in many studies. Each HRR includes at least one hospital capable of doing advanced heart surgery and brain surgery; the researchers chose to use these regions because dementia diagnosis and advanced treatment also requires specialized services.
In all, 143,029 of the people in the total population used in the study were newly diagnosed with Alzheimer’s or another form of dementia in 2019. The rest of the 356,656 people who had that diagnosis in this population had been diagnosed before 2019.
That means that overall, about 7% of people covered by traditional Medicare have a dementia diagnosis at any given time, and 3% of this population is diagnosed each year, with an average age at diagnosis of about 83 years.
The researchers then calculated the regional rates of new diagnoses and total diagnosed individuals as of 2019 for each HRR. The prevalence of diagnosed dementia ranged from as low as 4% to as high as 14% depending on HRR, and the rate of new dementia diagnoses in 2019 ranged from 1.7% to 5.4%.
They then looked at rates for three age groups – 66 to 74, 75 to 84 and 85 and over – and for people identified as white, Black or Hispanic. They also included data about the percentage of the population in each HRR that had less than a high school education, that smoked, and that had obesity or diabetes – all risk factors for dementia.
They also incorporated information about the general intensity of all kinds of chronic disease diagnosis in each HRR.
By taking all these factors into account, the researchers were able to calculate a predicted rate of diagnosis for new and total Alzheimer’s and dementia cases for each HRR, and for individuals in each HRR. This is what they called diagnostic intensity.
Compared to the national average, people residing areas of the lowest-intensity are 28% less likely to be diagnosed, whereas those residing in areas of the highest-intensity are 36% more likely to be diagnosed.
The general concentration of diagnosed dementia cases was highest in the southern U.S., similar to the “stroke belt” of high risk for stroke and cardiovascular disease.
But the South was no longer a uniform hotbed of dementia diagnosis once the researchers adjusted for the other factors.
