Most people who have mild cognitive impairment (MCI) don’t know it, so they’re unable to take advantage of preventive measures or new treatments, such as a recently approved drug for Alzheimer’s disease, that could slow its progression. Those are the findings of two new studies published in parallel by researchers at the USC Dornsife College of Letters, Arts and Sciences.
In one study, published in Alzheimer’s Research & Therapy, 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.
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.
The second study, published in Journal of Prevention of Alzheimer's Disease looked at 200,000 individual primary care clinicians and found that 99% of them underdiagnosed MCI.
There are several reasons MCI might be so widely underdiagnosed in the United States. An individual may not be aware of or bring up their concern; a physician might not notice subtle signs of difficulty; or a clinician might notice but not correctly 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.