Study finds correlation between dementia diagnosis rates and geographic location

New drugs for Alzheimer's disease and other types of dementia are on the market or in development, but a new study suggests that access to the diagnosis needed to receive these new treatments may vary depending on where you live.

Research has shown that the rate at which new cases of dementia are diagnosed each year varies widely across the U.S.

And the regional differences are even wider for younger dementia risk ages, people between 66 and 74, and black and Hispanic people.

In fact, studies have shown that in some parts of the United States, people are twice as likely to be diagnosed with dementia than in other parts of the country, suggesting that the likelihood of being diagnosed may depend more on the health care system than on the individual factors that influence dementia risk.

A formal diagnosis is necessary to access the latest dementia testing and treatments, many of which are aimed at slowing the progression of the earlier stages of dementia, called mild cognitive impairment or mild Alzheimer's disease.

The new study highlights regional differences in the “diagnostic intensity” of dementia — differences that exist even after accounting for all dementia risk factors and regional variations in population and healthcare.

Conducted by a team from the University of Michigan, Alzheimer's and DementiaIn: Alzheimer's Association Journal.

“These findings go beyond differences in demographics and population-level risk and suggest there are health system-level differences that can be targeted and improved,” said Julie Bynum, MD, MPH, a geriatric physician and medical researcher at UM Health who led the study.

The message is clear: the likelihood of being diagnosed with dementia varies from place to place, and can be due to everything from healthcare professionals' standards of practice to individual patients' knowledge and treatment-seeking behaviour. But the good news is that we can take action on these things if we know where to look.”

Julie Bynum, MD, MPH, professor of medicine at the U-M College of Medicine

Bynum and colleagues from the University of Michigan and the Geisel School of Medicine at Dartmouth College conducted the study using record data from 4.8 million people aged 66 or older who were enrolled in traditional Medicare in 2019.

About 7 million Americans have currently been diagnosed with dementia, but researchers note that there are probably millions more who have symptoms but have never been formally diagnosed.

New Insurance Coverage Biomarkers The treatment needed will depend on the diagnosis – tests, brain imaging scans and medication to slow the progression of dementia – but even for people who are not candidates for these treatments, a definitive diagnosis is important so that patients, and their family and friends who care for them, can receive specialised care and support.

Beyond risk factors: research details

Researchers have already found a number of factors associated with a higher risk of developing Alzheimer's disease and other dementias, including years of high blood pressure, high cholesterol, smoking and alcohol consumption, and poor levels of formal education, sleep and social interaction.

However, a new study shows for the first time that regional diagnostic differences cannot be explained by differences in dementia risk levels in different populations.

The study looked at diagnoses within 306 hospital referral regions developed for the Dartmouth Medical Atlas and used in many studies. Each HRR contains at least one hospital with advanced cardiac and brain surgery capabilities. The researchers chose to use these regions because dementia diagnosis and advanced treatment also require specialized services.

Of the total population studied, a total of 143,029 people were newly diagnosed with Alzheimer's disease or other forms of dementia in 2019. The remaining 356,656 people in this population who received the diagnosis had also been diagnosed prior to 2019.

So overall, about 7% of people covered by traditional Medicare are diagnosed with dementia at any one time, 3% of this population is diagnosed each year, and the average age at diagnosis is about 83 years.

The researchers then calculated the region-specific new diagnosis rates and total diagnosed people for each HRR as of 2019. The prevalence of people diagnosed with dementia ranged from 4% to 14% depending on the HRR, and the new dementia diagnosis rates in 2019 ranged from 1.7% to 5.4%.

They then looked at the proportions of people in three age groups — 66-74, 75-84, and 85 and older — and those identifying as white, black, and Hispanic. They also included data on the percentage of the population in each HRR who had less than a high school education, who smoked, and who were obese or had diabetes — all risk factors for dementia.

Each HRR also incorporated information on the general intensity of all types of chronic disease diagnoses.

Taking all these factors into account, the researchers were able to calculate predicted diagnostic rates of new and total cases of Alzheimer's disease and dementia for each HRR and for individuals within each HRR, which the researchers call diagnostic intensity.

Compared to the national average, 28% of people live in areas with the lowest intensity. few People living in the most affected areas are 36% more likely to be diagnosed. more likely to be diagnosed.

The overall concentration of diagnosed dementia cases was highest in the southern United States, which resembles a “stroke belt” with a higher risk of stroke and cardiovascular disease.

But once the researchers controlled for other factors, the South was no longer a hotbed of dementia diagnoses.

Impact on local change

Bynum explains that the findings could reflect variations in clinical practice — for example, how often primary care physicians test patients for early symptoms of dementia, or whether they have specialists available to make a definitive diagnosis.

Cultural and individual differences may also make a difference in the likelihood of seeking any care, scheduling a medical appointment specifically for memory concerns, or proactively communicating memory or thinking problems to a health care provider without being prompted during an existing appointment.

While the researchers cannot say for sure whether this difference is due to underdiagnosis or overdiagnosis, they say their new findings could be used to explore what barriers may prevent dementia diagnosis in areas where dementia diagnosis rates are lower than expected.

“The goal these days should be to identify people with cognitive impairment early, but our data shows that younger age groups have the most variability in Medicare enrollment,” Bynum said. “For communities and health systems, this should be a call to action to spread knowledge and try to get services available to people. And for individuals, it's a message that they may need to advocate for themselves to get what they need, like cognitive testing.”

She added that Medicare covers cognitive function testing during enrollees' annual physical exams.

She also points to Medicare's recently launched GUIDE model for dementia care, which encourages clinical offices to better coordinate dementia care and provide 24-hour access to trained providers, which may offer a path to improved care.

In addition to Bynum, the study authors are Slim Benruciv and Jonathan Martindale of the University of Michigan Department of Internal Medicine, A. James O'Malley of Dartmouth College, and Matthew A. Davis, PhD, of the University of Michigan School of Nursing and the University of Michigan Medicine School of Learning and Health Sciences.

Bynum and Davis are members of the University of Michigan Institute for Health Policy and Innovation and leaders of the Center for Advancing Population Research on Alzheimer's Disease (CAPRA).

This research was funded by the National Institute on Aging at the National Institutes of Health (P01AG019783).