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Mild cognitive impairment – an early stage of dementia – is widely underdiagnosed in people 65 and older. That is the key takeaway of two recent studies from our team.

In the first study, we used Medicare data for about 40 million beneficiaries age 65 and older from 2015 to 2019 to estimate the prevalence of mild cognitive impairment in that population and to identify what proportion of them had actually been diagnosed.

Our : A mere 8% of the number of cases with mild cognitive impairment that we expected based on a statistical model had actually been diagnosed. Scaled up to the general population 65 and older, this means that approximately 7.4 million cases across the country remain undiagnosed.

In the second study, we analyzed data for 226,756 primary care clinicians and found that in this population.

Why it matters

Mild cognitive impairment is an early symptom of Alzheimer’s disease in and progresses to dementia . It includes symptoms such as losing the ability to remember recent events and appointments, make sound decisions and master complex tasks. Failure to detect it might deprive patients of an opportunity to get treated and to slow down disease progression.

Mild cognitive impairment can sometimes be caused by easily addressable factors, such as medication side effects, thyroid dysfunction or . Since mild cognitive impairment has , such as high blood pressure and cholesterol, medication management of these risks combined with diet and exercise .

In 2023, the Food and Drug Administration as the , the most common cause of mild cognitive impairment. In contrast to previous drugs, which can temporarily improve symptoms of the disease, such as memory loss and agitation, this new treatment addresses the underlying cause of the disease.

Lecanemab, a monoclonal antibody, in the brain, which are toxic protein clumps that are believed to contribute to the progression of the disease. In a large clinical trial, lecanemab was able to of early-stage Alzheimer’s disease. A similar drug, donanemab, also and is expected to be .

However, these drugs must be used in the early stages of Alzheimer’s disease, ideally when a patient has only mild cognitive impairment, as there is .

What still isn’t known

Many factors contribute to the . But researchers don’t have a good understanding of the relative importance of those individual factors or how to reduce the high rate of underdiagnosis.

While distinct, symptoms are subtle and their slow progression means that they can be overlooked or misinterpreted as normal aging. A neurologist in China told our research team that diagnosis rates spike in China after the New Year’s holiday, when children who haven’t seen their parents for a year notice changes that are harder to pick up when interacting with someone daily.

Doctors also commonly discount memory concerns as normal aging and doubt that much can be done about it. While cognitive tests to distinguish mild cognitive impairment from pathologic decline do exist, they take about 15 minutes, which can be hard to come by during the limited time of a doctor’s visit and may require a follow-up appointment.

What’s next

People, particularly those in their 60s and beyond, as well as their families and friends need to be vigilant about cognitive decline, bring it up during doctor’s appointments and insist on a formal assessment.

The is an opportunity to explore such concerns, but only about half of beneficiaries .

Just as physicians ask patients about unexplained weight loss and take those concerns seriously, we believe questions that explore a patient’s cognitive state need to become the norm.

The is a short take on interesting academic work.

Soeren Mattke receives funding from Alzheon, Biogen, C2N, Eisai, Lilly and Roche/Genentech through the University of Southern California. He consults to Biogen, C2N, Eisai, Novartis, Novo Nordisk and Roche/Genentech.

Ying Liu receives funding from Genentech, a member of the Roche Group, through the University of Southern California.