Image by Gerd Altmann from Pixabay
In a new study, Yale researchers discovered that most older Americans who have a dementia diagnosis in their medical records don’t report having one.
September 22, 2026 - By Meg Dalton - Most research on the diagnosis of dementia focuses on people who are never diagnosed. But in a new study, Yale researchers look at the other side: people who have been diagnosed but do not know it, or do not acknowledge it.
In an analysis of U.S. survey data of older Americans with probable dementia, the researchers found that about two-thirds (67%) of respondents who’d answered questions for themselves reported that no doctor had ever told them they had dementia, even though Medicare claims indicated such a diagnosis. That is far higher than for other conditions among the very same people, such as high blood pressure (23%) or arthritis (17%).
Such levels of underreporting suggest that many of these patients are also likely not pursuing critical medical services related to their diagnosis, the researchers say.
“A diagnosis that sits in a chart but never registers with the patient delivers almost none of the benefits that early detection is supposed to bring,” said Xi Chen, corresponding author of the study and an associate professor of public health and economics at Yale University.
The study appears in the journal JAMA Network Open.
Many people with dementia go undiagnosed. While a few small, cross-sectional studies had previously suggested that even diagnosed patients are often unaware, nobody had tracked it over the course of the disease, compared it to other conditions in the same patients, identified who is most affected, or asked whether it matters for the care people actually receive.
For the new study, researchers wanted to fill in those gaps. They used the Health and Retirement Study, a nationally representative survey of older Americans that has followed the same people every two years since the 1990s, and which is linked to their Medicare claims. Using that data, they identified people aged 65 and older with probable dementia based on validated cognitive testing, then found the specific survey wave in which their Medicare records contained a dementia diagnosis.
The researchers checked whether the individuals reported, in that same period, that a doctor had told them they had dementia or a memory-related disease. They investigated the same information for four other conditions (arthritis, hypertension, diabetes, and depression) for comparison, examined which patient and health-system factors predicted underreporting, and looked at whether underreporting was linked to doctor visits, flu shots, and having a will or trust in the year after diagnosis. In all, they analyzed thousands of observations from about 3,300 people.
Reducing stigma
Through their methods, the researchers found that two-thirds of self-reporting patients with a documented dementia diagnosis did not report it, compared with an average of about 31% for the other conditions. Underreporting was highest (82%) in the earliest years after diagnosis, before measurable cognitive decline, and was more common among people living alone, with less education, or with lower incomes, and among Black older adults. It was less common among patients who saw a dementia specialist, were diagnosed in an outpatient clinic rather than a hospital, or were enrolled in Medicare Advantage, a comprehensive plan offered by some private companies as an alternative to the traditional fee-for-service Medicare plans.
Patients who underreported were also about 30% less likely to visit a doctor for a health problem, 37% less likely to receive a flu shot, and 30% less likely of having a will or trust in the following year. Importantly, the same patients still reported their other conditions at normal rates, the researchers found, indicating that a lack of reporting is not related to memory loss.
Taken together, the findings suggest a mix of stigma, difficulty accepting the diagnosis, and, above all, inadequate communication by the health system, the researchers said.
“Diagnosing dementia is only the first step,” Chen said. “A diagnosis is only useful if the patient and family understand it and can act on it. Clinicians need the time, training, and support to deliver this news clearly and compassionately, and patients and families should feel empowered to ask.”
Chen added: “Reducing the stigma around dementia is a shared responsibility: the more openly we talk about it, the easier it becomes to accept a diagnosis and get the help that is available.”
Other Yale authors include the lead author Yuting Qian, a recent Ph.D. graduate who is now a postdoctoral associate at Yale School of Public Health, and Kyle Gavulic, a medical and doctoral student at Yale School of Medicine and the Yale School of Public Health.
The study was supported by the National Institute on Aging.
What you need to know
How many Americans with dementia report not having a diagnosis?
Yale researchers analyzed thousands of observations from about 3,300 people. Among those who answered survey questions for themselves, two-thirds (67%) said no doctor had ever told them they had dementia, even though Medicare claims showed a documented diagnosis. That is far higher than for other conditions in the very same people, such as high blood pressure (23%) or arthritis (17%).
Why is important for patients to be aware of their dementia diagnosis?
If a dementia diagnosis never registers with a patient who has been diagnosed, they are unlikely to pursue and receive the health benefits that early detection is supposed to bring. With new disease-modifying treatments and Medicare’s growing investment in early detection, the gap between a documented diagnosis and a patient’s awareness is becoming a critical, and largely invisible, barrier to care.
How important is a dementia diagnosis?
Diagnosing dementia is only the first step. A diagnosis is only useful if the patient and family understand it and can act on it. Clinicians need the time, training, and support to deliver this news clearly and compassionately, and patients and families should feel empowered to ask.
Source: Yale School of Medicine
