Mild Cognitive Impairment Undiagnosed In Over 7 Million Americans

undiagnosed mild cognitive impairment

For many people, forgetting your keys or having difficulty planning tasks may appear to be a typical part of aging. However, those gaps may be signs of something more serious: mild cognitive impairment, or MCI, which could be an early sign of Alzheimer’s disease.

Unfortunately, because most people with MCI are unaware of it, they are unable to benefit from preventive measures or novel treatments, such as a recently approved medicine for Alzheimer’s disease, that could halt its progression. These are the conclusions of two recent studies published concurrently by USC Dornsife College of Letters, Arts, and Sciences academics.

In one study, published in Alzheimer’s Research & Therapy, researchers examined data from 40 million Medicare users aged 65 and older and compared the proportion diagnosed to the expected rate for this age group. They discovered that only around 8% of the predicted 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.

Raising Awareness

Raising awareness of the issue is the study’s main intention, Soeren Mattke, director of the Brain Health Observatory at USC Dornsife’s Center for Economic and Social Research, who led the investigations, said.

Pathologic cognitive decline is measurably different from normal aging, and early detection of the latter may help identify patients who could benefit from newly approved treatments for Alzheimer’s disease.

Clinical and socioeconomic factors have an impact on the prevalence of MCI. People with cardiovascular disease, diabetes, hypertension and other health issues are at higher risk of cognitive decline, including dementia.

Black and Hispanic Americans, as well as those from historically underprivileged backgrounds, are more likely to experience these health problems. The researchers found that detection of MCI was even poorer in those groups.

This is concerning because those populations have a higher overall disease burden.

“So, they’re hit twice: They have higher risk and yet lower detection rates,”

Mattke said.

Tiny Fraction of Physicians

A second study that examined 200,000 primary care physicians revealed that 99% of them misdiagnosed MCI. It was published in the Journal of Prevention of Alzheimer’s Disease.

“There’s really just a tiny fraction of physicians in a position to diagnose MCI who would find these cases early enough for maximum therapeutic potential,”

Mattke explained.

Mild cognitive impairment, by definition, doesn’t cause disability, whereas dementia is itself a disabling condition reflecting more serious cognitive impairment. According to Soo Borson, clinical professor of family medicine at the USC Keck School of Medicine and co-director of the BOLD Center on Early Detection of Dementia, who was not involved in the studies, challenges to daily functioning are more sporadic in MCI.

MCI can manifest itself in a variety of forms, with forgetfulness being the most common, according to Borson. Another type is an executive form, which mostly affects productivity and difficulties with chores that used to be simple, such as balancing a checkbook or paying bills online.

There is even a behavioural form — in which mild changes in personality may predominate. These various forms often coexist.

Reasons for Undiagnosed MCI

It is important to understand that mild cognitive impairment refers to a level of cognitive functioning and not a specific disease state. Recent advances in the treatment of the most common cause of MCI — Alzheimer’s disease — lend new urgency to improving detection of MCI.

There are various reasons why MCI might be so commonly misdiagnosed in the United States. A person may be unaware of or fail to express their worry; a physician may miss subtle signals of trouble; or a clinician may observe but fail to appropriately enter the diagnostic code 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.

According to Mattke, risk-based MCI detection — focusing attention on persons who are most at risk — would help uncover more instances since time and resources might be concentrated on those at high risk. Digital assessments that might be given prior to a medical visit could also assist more people in learning about their cognitive risk and present functioning.

Early treatment is vital, pointed out 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. This means even though the disease may be slowly progressing, every day counts,”

he said.

  1. Mattke, S., Jun, H., Chen, E. et al. Expected and diagnosed rates of mild cognitive impairment and dementia in the U.S. Medicare population: observational analysis. Alz Res Therapy 15, 128 (2023). DOI: 10.1186/s13195-023-0127
  2. Mattke, S., et al. Detection Rates of Mild Cognitive Impairment in Primary Care for the United States Medicare Population, The Journal of Prevention of Alzheimer s Disease (2023). DOI: 10.14283/jpad.2023.131