What Is Mild Cognitive Impairment, and How is it Diagnosed?

Mike Davis’s mother died from Alzheimer’s disease in 2008. So when Mr. Davis started noticing that he was having an increasing number of “senior moments” at age 76 — such as forgetting to water his plants, something he was normally regimented about — he decided to have his cognition tested.

After administering an evaluation, Mr. Davis’s doctor told him he had mild cognitive impairment.

Millions of Americans are thought to have M.C.I., though exact numbers are hard to pin down because experts say the condition is underdiagnosed. There are likely several reasons for that: M.C.I. can be tricky to identify during a primary care visit, when physicians typically only have 15 minutes or so with a patient. People may also be scared to disclose their concerns to a doctor, or might not even realize that they have a problem.

Here’s what to know about what M.C.I. is and how it’s diagnosed.

What is M.C.I.?

M.C.I. most often stems from a neurodegenerative disorder, such as Alzheimer’s disease, but cognitive impairments could also be caused by a reversible issue, like a vitamin deficiency, sleep disorder or medication side effect. If M.C.I. is due to a neurodegenerative condition, it can progress to dementia, though how long that takes varies widely. According to the Alzheimer’s Association, about 10 to 15 percent of people with M.C.I. develop dementia each year.

“Mild cognitive impairment is the stage before dementia where there are more thinking problems than we would expect for your age,” explained Andrew Kiselica, a neuropsychologist at the University of Missouri who specializes in diagnosing dementia. “But there’s still a level of independence there, where you’re not relying on other people for day-to-day functioning.”

It can be hard to know what’s normal forgetfulness with age and what’s a sign that something may be wrong. Dr. Kiselica said that one indication of possible M.C.I. is if a person has to start implementing strategies to help them keep up with basic activities. “They’re remembering their medications or what to pick up with shopping, but they have to use a lot more to-do lists to make sure they’re getting those things done,” he said.

Or there might be “telling events” of forgetfulness, said Dr. Halima Amjad, an assistant professor of medicine specializing in geriatrics at the Johns Hopkins University School of Medicine. Not just, “‘Oh, I forgot my phone. I forgot what I came to this room for,’” which everyone experiences from time to time, she said, but, “‘Gosh, I had to call someone because I couldn’t find my car in the parking lot.’”

How is it diagnosed?

Most people are first screened for M.C.I. and dementia in their primary care doctor’s office. Medicare requires physicians to assess cognitive health at the annual wellness visit, which people are eligible for starting at 65, though those screens can be as basic as asking the patient whether they’ve noticed any issues with their memory. Typically, a physician only initiates a longer dementia test if the patient or a family member has expressed concern, Dr. Amjad said.

If you’re worried that a loved one may be experiencing memory loss and think they should be evaluated, try to broach the topic with them in a way that’s empathetic and nonconfrontational. Dr. Kiselica recommends emphasizing that if they get tested, you could be proven wrong. For example: “I’ve noticed you seem to be having some memory problems, repeating yourself and forgetting things I’ve said. I could be mistaken, and if we go to the doctor, they can tell us one way or another.”

If the person is resistant, you can also try calling their physician ahead of an upcoming appointment to relay your concerns. That puts cognition “on the doctor’s radar so the doctor can ask, think about doing some tests,” Dr. Amjad said.

Two commonly used cognitive tests to diagnose M.C.I. and dementia are the Mini-Mental State Exam and the Montreal Cognitive Assessment. Both take about 10 minutes and involve questions evaluating memory, attention, verbal ability and general awareness. For example, the doctor might ask the patient to remember a few words and recount them several minutes later, name as many animals as they can or count backward by groups of seven.

Scores below a certain threshold are classified as M.C.I., followed by mild, moderate and severe dementia. However, the cutoff scores may not be accurate for the entire population. For example, Black and Hispanic older adults score worse, on average, than white older adults, which researchers say is likely in part because of systemic differences in educational opportunities. As a result, some experts recommend different cutoffs based on race and ethnicity.

To Dr. Amjad, the tests are one piece of information in a bigger picture. The patient’s impression of their own abilities, plus a family member’s account, are just as important if not more so, she said.

What comes next?

If a person is diagnosed with M.C.I., they may be referred for more extensive cognitive testing with a neuropsychologist, and they should receive other assessments, like brain scans and blood tests, to determine what the underlying cause of their issue might be.

A diagnosis alone can’t explain what’s behind a person’s symptoms, said Dr. Carolyn Fredericks, an assistant professor of neurology at Yale School of Medicine. “And that, of course, is the most important piece and the one that has the most meaning for the patient in terms of, ‘How worried should we be, and what does this mean for the future?’”

But the first step is to get your cognitive health evaluated. If you’re concerned about your memory, “Go see a doctor,” encouraged Mr. Davis, who has managed his M.C.I. for five years by staying physically and mentally active.

“Start thinking about this as part of the physical exam,” added Dr. Amjad. Just like physicians check your heart and your lungs, “this is a way for us to test the brain.”