Adding screening for cognitive difficulties could help millions, say USC Dornsife researchers. (Composite: Letty Avila. Image source: iStock.)

Missed diagnosis: The hidden crisis of mild cognitive impairment in America

Two new USC Dornsife studies suggest that of the 8 million Americans who have MCI, more than 90% don’t know it — an especially worrisome finding since early diagnosis is key to delaying onset of dementia and Alzheimer’s disease.
ByKatharine Gammon

After moving back to Oceanside, Calif., Jean Bland looked forward to reconnecting with the familiar streets of her youth. But not long after settling in, her husband Mike noticed that Jean, with whom he’d shared 41 years of marriage, would occasionally find herself lost in the very places she once knew so well. Initially concerned, he dismissed it as a common sign of aging.

Jean, 79, a former nurse known for her meticulous nature and attention to detail, always came prepared to her doctor’s appointments, armed with a litany of questions and notes. So, when she walked into the exam room two years ago without any list and displayed signs of forgetfulness, it raised eyebrows. Her physician, sensing something wasn’t right, recommended a series of tests, including an extensive verbal examination.

The diagnosis revealed that Jean had mild cognitive impairment (MCI), a condition often linked to Alzheimer’s disease. While the news was daunting, it also presented her with a silver lining: the opportunity to take proactive measures, including a new drug — which is only effective when cognitive impairment is mild — to potentially slow the disease’s progression. More than 7 million other Americans, unaware of their condition, aren’t as fortunate.

Two studies from the USC Dornsife College of Letters, Arts and Sciences reveal that MCI is alarmingly under-diagnosed, with approximately 7.4 million unknowingly living with the condition. Even more startling, half of these individuals are silently battling Alzheimer’s disease.

‘Pay attention to early changes in cognition, and tell your doctor about them.’

Jean was immediately afraid of the diagnosis, she says. She also resisted the news; she didn’t have a memory issue, she insisted. But she had noticed little changes in her life — strangely, she couldn’t smell roses anymore.

She asked for a referral to a neurologist, who performed an MRI, but it didn’t show anything abnormal. After seeing another doctor, she eventually got the official diagnosis of mild Alzheimer’s disease, and it hit her like an asteroid.

“It was a horror,” Jean says. “It scared me to death. I really didn’t know how to handle it at the moment, so I had to think about it and read about it and eventually admit that something was wrong.”

Widespread underdiagnosis of MCI

In one study, the researchers analyzed data from 40 million Medicare beneficiaries age 65 and older and compared the proportion diagnosed with the rate expected in this age group. They found that fewer than 8% of expected cases were actually diagnosed. In other words, of the 8 million individuals predicted to have MCI based on their demographic profile, which includes age and gender, about 7.4 million were undiagnosed.

“This study is meant to raise awareness of the problem,” says Soeren Mattke, director of the Brain Health Observatory at USC Dornsife’s Center for Economic and Social Research, who led the investigations. “We want to say, ‘Pay attention to early changes in cognition, and tell your doctor about them. Ask for an evaluation.’”

The prevalence of MCI is influenced by socioeconomic and clinical factors. People with cardiovascular disease, diabetes, hypertension and other health issues are at higher risk of cognitive decline including dementia. These health issues are more prevalent among members of historically disadvantaged groups, including those with less education and Black and Hispanic Americans.

The researchers found that detection of MCI was even poorer in those groups. Mattke says that’s concerning because the overall disease burden in those populations is higher. “So, they’re hit twice: They have higher risk and yet lower detection rates.”

The second study looked at 200,000 individual primary care clinicians and found that 99% of them underdiagnosed MCI.

I don’t want to lose her. Not just physically, but mentally, too.

“There’s really just a tiny fraction of physicians … who would find these cases early enough for maximum therapeutic potential,” Mattke explains.

MCI by definition doesn’t cause disability whereas dementia is a disabling condition marked by more serious cognitive difficulties. In MCI, challenges to everyday functioning tend to be more sporadic, says Soo Borson, clinical professor of family medicine at Keck School of Medicine of USC, who was not involved in the studies.

MCI can come in various forms: Forgetfulness is the most familiar form, Borson says. Another is an executive form, which mainly affects efficiency in getting things done and difficulty with tasks that used to be easier, such as balancing a checkbook or paying bills online. There is even a behavioral form in which mild changes in personality may predominate. These various forms often coexist.

MCI might be underdiagnosed for various reasons. An individual may not be aware of or bring up a concern; a physician might not notice subtle signs of difficulty; or a clinician might mistakenly enter a diagnostic code incorrectly in a patient’s medical record.

Another important reason: Time during a clinical visit may not be set aside to discuss or assess brain health unless the visit was planned expressly to include it. Detection of cognitive impairment is not difficult, but it does not occur without planning.

Early detection key to better outcomes for MCI

But early treatment is vital, says Mattke, because the brain is limited in its ability to recover — brain cells, once lost, do not grow back, and any damage can no longer be repaired.

“For MCI caused by Alzheimer’s disease, the earlier you treat, the better your outcomes,” he says. “This means even though the disease may be slowly progressing, every day counts.”

Time is of the essence, and Mike and Jean are now coming up with a game plan for their lives. Jean is taking medication to slow the process of MCI, but she struggles with minor functions. She sometimes repeats questions, and Mike finds himself making up little stories. He knows there’s no cure, and even the newest medications can only slow the process, so it leads to anxiety about the future.

Mike’s voice wavers as he admits, “I don’t want to lose her. Not just physically, but mentally, too.” He’s now an advocate for early testing but wonders at what point someone can realize they need help. “How do you as an individual determine what’s happening when you can’t find your keys or remember where the milk in the refrigerator is? Is that old age or is that really a memory issue?”

Jean is grateful to have more information. Early on in her memory loss, she started to see strangers and even her deceased father in the family room of the house, and it would frighten her. Now she knows that hallucinations are part of cognitive impairment, and it gives her some comfort. “I don’t have that pressing against me anymore,” she says. “It’s easier to go through life now.”

They are learning to go out to lunch more, take walks and do errands together. Mike says they hug and kiss more now than ever before in their relationship.

“I am very lucky,” Jean says, as she tenderly takes Mike’s hand in hers.

He responds, “I am too.”

DISCLOSURE: Genentech was a funder for both papers but had no role in the design and conduct of the studies.