More Than 7 Million Americans With Mild Cognitive Impairment Don't Realize They Have It

Fact checked by Nick Blackmer

• Millions of Americans don’t know they have Mild Cognitive Impairment (MCI), according to new research.

• The condition causes memory problems that are more severe than those associated with normal aging.

• There's no one cause of MCI, though it may often be an early sign of Alzheimer's disease.

More than seven million Americans may not know they have mild cognitive impairment (MCI), a condition that mostly affects people over the age of 65 and is sometimes an early sign of Alzheimer’s disease, new research suggests.

Two separate studies recently published by researchers at the University of Southern California Dornsife College of Letters, Arts, and Sciences suggest that MCI isn’t discussed nearly enough in clinical settings.

This can be detrimental since, in some cases, early treatment is essential, Soeren Mattke, MD, DSc, director of the Center for Improving Chronic Illness and Care at USC Dornsife and an author on both new studies, told Health. “If you have early-stage cognitive impairment and let it linger and don’t address it, you lose time and the potential for” early interventions, said Mattke.

Among the biggest reasons that MCI may go undiagnosed is that it’s not one single disease—it's an umbrella term for a group of symptoms that can stem from many different causes, Saket Saxena, MD, a geriatrician at Cleveland Clinic, told Health. “Mild cognitive impairment is underdiagnosed because it is not a singular entity, and it is difficult to diagnose to begin with,” said Saxena.

Below, experts explain what MCI looks like, why doctors often miss it, and what potential treatment options look like.

Detection Rates for MCI Are Very Low

The first of the two new studies, published in Alzheimer’s Research & Therapy in July, analyzed data from 40 million people aged 65 or older who had Medicare insurance from 2015 to 2019.

They determined how many people in this category likely had MCI by analyzing data from the Health and Retirement Study (HRS), a longitudinal panel study conducted by the University of Michigan that surveys thousands of Americans about their health and wellness every two years.

The researchers then compared the number of people who likely should have received an MCI diagnosis to the number of Medicare beneficiaries who did.

What they found was that MCI wasn’t diagnosed nearly as often as it should have been. Though MCI detection rates increased slightly from 2015 to 2019, only about 8% of expected cases were diagnosed—leaving the rest, an estimated 7.4 million cases, undiagnosed.

For the second study, published in October in The Journal of Prevention of Alzheimer’s Disease, the researchers relied on data from the offices of 226,756 primary care clinicians and 54,597 doctors’ offices. To be included in the study, the clinicians or practices had to have at least 25 patients who were 65 or older and enrolled in Medicare insurance.

The researchers found that about 99% of clinicians underdiagnosed MCI and that, among both clinicians and practices, only about 8% of expected cases were diagnosed on average.

Mattke said he found this discrepancy particularly surprising. “It was clear the detection rates would be low, but finding that 99% of physicians don’t do a good job diagnosing [MCI]—the magnitude of that gap was wider” than expected, he said.

Related: Most Older Adults Don't Know You Can Test for Alzheimer's Disease

What Is MCI—and Why Is Early Detection So Important?

MCI causes symptoms that overlap with those of Alzheimer’s and dementia, according to Saxena. The distinguishing factor, he said, comes down to how drastically those symptoms affect a person’s day-to-day life.

“Mild cognitive impairment, by definition, is a memory problem which is there but doesn’t affect a person’s ability to function. The difference between MCI and dementia is a person’s ability to function and take care of their basic needs,” he said. “That’s where we draw the line.”

The symptoms of MCI include difficulty remembering words, forgetting to attend important events, and losing things frequently. These symptoms are more advanced than those of normal aging—such as forgetting which words to use and occasionally losing things—but less severe than those of Alzheimer’s—such as getting lost in places that should be familiar, or having hallucinations.

About 10 to 20% of people over the age of 65 likely have MCI and a person’s risk increases with their age.

A number of issues can cause MCI, said Mattke, but the most common cause is Alzheimer’s. Some causes are reversible or treatable. For example, having a bad reaction to a certain medication or drinking too much can cause MCI. Other potential causes include depression, heightened stress, social isolation, or even untreated chronic conditions, such as heart failure or sleep apnea, said Saxena.

Treatment for MCI largely depends on what’s causing the symptoms. For instance, if a person’s MCI symptoms are being caused by depression, seeking treatment for the depression may solve the problem, said Saxena. If they’re experiencing MCI because of a reaction to a new medication, stopping that medication may solve the problem.

But early detection of MCI is important because, in some cases, the underlying causes can be treated better when caught early. “The earlier you treat Alzheimer’s disease, the better,” said Mattke. Most drugs for Alzheimer’s work better in people who aren’t in the advanced stages of the disease.

Related: Alzheimer's Disease Is Most Common in These Areas of the U.S.

Better Doctor-Patient Communication Needed for Increased Detection Rates

The vagueness with which MCI is defined is one of the reasons it goes undiagnosed so often. The fact that the symptoms aren’t as drastic as those of Alzheimer’s also contributes to the low detection rates.

“[MCI] is a pretty broadly defined category of memory problems,” said Mattke. “The symptoms are not severe, and since they occur mostly in elderly people, they often get discounted as just getting older. People think, ‘That’s just the way it is.’”

Older people often simply adapt to memory issues, rather than bringing them up to their provider, he added. “They find a way to adjust to it,” said Mattke. “[For instance,] they may just stop driving at night because orientation is harder when it’s dark.”

People should not wait to see a doctor if they’re experiencing memory trouble, said Saxena, explaining that any symptom of MCI—no matter how small it may seem—is a good reason to get evaluated.

If a doctor brushes off worrisome symptoms as normal signs of aging, it may be helpful to see an expert, such as a geriatrician, neurologist, or neuropsychologist.

Given that the symptoms are often non-specific or aren’t particularly alarming, doctors may be more inclined to watch patients with MCI symptoms rather than diagnose them with something immediately. “Many physicians don’t take early memory problems seriously,” said Mattke. “When patients do bring them up, they’ll say, ‘Come see me again in a year and we’ll see what’s happening’” if your symptoms persist.

But for MCI detection rates to improve, doctors need to be more mindful of what may be causing a person’s memory problems, and understand that they may not be age-related, Mattke added.

Ultimately, doctors need to consider the whole picture when determining what may be causing memory trouble. “Mild cognitive impairment should be approached with a broader lens,” said Saxena. “A person’s overall [well-being]—looking at their mood, mobility, social stress, making sure their blood tests are checked—all of these things need to be looked into so that we can do better by our patients.”

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