Is Mild Cognitive Impairment Severely Underdiagnosed?

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Mild cognitive impairment—lapses such as missing appointments, losing things, and having trouble finding the words to describe something—affects millions of older adults across the United States. Yet because it’s so common in later life, many people ignore or brush aside the condition.

A 2023 study sought to quantify exactly how many older adults have mild cognitive impairment, and how often the condition is diagnosed by a doctor. The study, published by UCLA researchers in the journal Alzheimer's Research & Therapy, used Medicare data collected between 2015 and 2019 for more than 40 million Americans aged 65 and older. Using statistical algorithms, they calculated that approximately 8 million older adults are affected by mild cognitive impairment.

The researchers then conducted a second analysis to determine how many of these cases of mild cognitive impairment received formal diagnoses. The answer: less than 8 percent.

Why Underdiagnosis of Minor Cognitive Impairment Matters

The lack of diagnoses is important, the researchers explain, for several reasons.

Sometimes, mild cognitive impairment symptoms can improve significantly by adjusting medications or addressing thyroid dysfunction or a vitamin deficiency. Managing some of the risk factors for mild cognitive impairment, such as high blood pressure and cholesterol, can also improve symptoms.

Even more importantly, mild cognitive impairment is often a precursor to Alzheimer’s disease; each year, 10 to 15 percent of people with mild cognitive impairment will develop more serious dementia.

Last year, the U.S. Food and Drug Administration approved a new medicine called lecanemab that addresses the underlying causes of Alzheimer’s disease instead of simply improving symptoms. (It works by reducing plaque build-up in the brain.) Another similar drug is awaiting approval this year.

But there’s a catch: These medicines must be administered in the early stages of the disease. A diagnosis of mild cognitive impairment is therefore critical because it provides the opportunity for doctors to prescribe these new medicines, and potentially delay the onset of Alzheimer’s disease.

What Can Be Done About Underdiagnosis

What’s the best way to address this problem of underdiagnosis? One strategy is for relatives and medical professionals to pay more attention to early symptoms of cognitive impairment. There are screening tests, which take about 15 minutes, which can help to distinguish mild cognitive impairment from normal aging. Performing these screenings anytime there is a question about whether an older adult is experiencing mild cognitive impairment is a first step.

The take-home message: Mild cognitive impairment is ubiquitous and underdiagnosed throughout the U.S. But identifying mild cognitive impairment early can help doctors address its symptoms and create the opportunity to prescribe medicines that could slow the progression of dementia or Alzheimer’s disease in the long run.