What do doctors mean by mild cognitive impairment?
The approval of a controversial new drug for Alzheimer’s disease, Aduhelm, is shining a spotlight on mild cognitive impairment — problems with memory, attention, language or other cognitive tasks that exceed changes expected with normal aging.
After initially indicating that Aduhelm could be prescribed to anyone with dementia, the Food and Drug Administration now specifies that the prescription drug be given to individuals with mild cognitive impairment or early-stage Alzheimer’s, the groups in which the medication was studied.
Yet this narrower recommendation raises questions. What does a diagnosis of mild cognitive impairment mean? Here’s what people should know based on a review of research studies and conversations with leading experts.
BASICS OF MILD COGNITIVE IMPAIRMENT
Mild cognitive impairment is often referred to as a borderline state between normal cognition and dementia. But this can be misleading. Although a significant number of people with mild cognitive impairment eventually develop dementia — usually Alzheimer’s disease — many do not.
Cognitive symptoms — difficulties with shortterm memory or planning — are often subtle but they persist and represent a decline from previous functioning. Yet a person with the condition may still be working or driving and appear entirely normal. By definition, mild cognitive impairment leaves intact a person’s ability to perform daily activities independently.
According to an American Academy of Neurology review of dozens of studies, published in 2018, mild cognitive impairment affects nearly 7% of people ages 60 to 64, 10% of those 70 to 74 and 25% of 80- to 84year-olds.
CAUSES
Mild cognitive impairment can be caused by biological processes (the accumulation of amyloid beta and tau proteins and changes in the brain’s structure) linked to Alzheimer’s disease. Between 40% and 60% of people with mild cognitive impairment have evidence of Alzheimer’srelated brain pathology, according to a 2019 review.
But cognitive symptoms can also be caused by other factors, including small strokes; poorly managed conditions such as diabetes, depression and sleep apnea; responses to medications; thyroid disease; and unrecognized hearing loss. When these issues are treated, normal cognition may be restored or further decline forestalled.
SUBTYPES
During the past decade, experts have identified four subtypes of mild cognitive impairment. Each subtype appears to carry a different risk of progressing to Alzheimer’s disease, but precise estimates haven’t been established.
People with memory problems and multiple medical issues who are found to have changes in their brain through imaging tests are thought to be at greatest risk. “If biomarker tests converge and show abnormalities in amyloid, tau and neurodegeneration, you can be pretty certain a person with MCI has the beginnings of Alzheimer’s in their brain and that disease will continue to evolve,” said Dr. Howard Chertkow, chairperson for cognitive neurology and innovation at Baycrest, an academic health sciences center in Toronto that specializes in care for older adults.
DIAGNOSIS
Usually, this process begins when older adults tell their doctors that “something isn’t right with my memory or my thinking” — a so-called subjective cognitive complaint. Short cognitive
Much of the debate centers on the complex method used to pay the health plans.
In original Medicare, medical providers bill for each service they provide. By contrast, Medicare Advantage plans are paid using a coding formula called a “risk score” that pays higher rates for sicker patients and less for those in good health.
That means the more serious medical conditions the plans diagnose the more money they get — sometimes thousands of dollars more per patient over the course of a year with little monitoring by CMS to make sure the higher fees are justified.
Congress recognized the problem in 2005 and directed CMS to set an annual “coding intensity adjustment” to reduce Medicare Advantage risk scores and keep them more in line with original Medicare.
But since 2018, CMS has set the coding adjustment at 5.9%, the minimum amount required by law. Boccuti said that adjustment is “too low,” adding that health plans “are inventing new ways to increase their enrollees’ risk scores, which gain them higher monthly payments from Medicare.”
Some of these coding strategies have been the tests can confirm whether objective evidence of impairment exists. Other tests can determine whether a person is still able to perform daily activities successfully.
More sophisticated neuropsychological tests can be helpful if there is uncertainty about findings or a need to better assess the extent of impairment. But “there is a shortage of physicians with expertise in dementia — neurologists, geriatricians, geriatric psychiatrists” — who can undertake comprehensive evaluations, said Kathryn Phillips, director of health services research and health economics at the University of CaliforniaSan Francisco School of Pharmacy.
The most important step is taking a careful medical history that documents whether a decline in functioning from an individual’s baseline has occurred and investigating possible causes such as sleep patterns, mental health concerns and inadequate management of chronic conditions that need attention.
Mild cognitive impairment “isn’t necessarily straightforward to recognize, because people’s thinking and memory changes over time [with advancing age] and the question becomes ‘Is this something more than that?’” said Dr. Zoe Arvanitakis, a neurologist and director of Rush University’s Rush Memory Clinic in Chicago.
More than one set of tests is needed to rule out the possibility that someone performed poorly because they were nervous or sleep-deprived or had a bad day. “Administering tests to people over time can do a pretty good target of whistleblower lawsuits and government investigations that allege health plans illegally manipulated risk scores by making patients appear sicker than they were, or by billing for medical conditions patients did not have. In one recent case, the Justice Department accused Kaiser Permanente health plans of obtaining about $1 billion by inflating risk scores. In a statement, the insurer disputed the allegations. (KHN is not affiliated with Kaiser Permanente.)
Legal or not, the rise in Medicare Advantage coding means taxpayers pay much more for similar patients who join the health plans than for those in original Medicare, according to Kronick. He said there is “little evidence” that higher payments to Medicare Advantage are justified because their enrollees are sicker than the average senior.
Kronick, who has studied the coding issue for years, both inside government and out, said that risk scores in 2019 were 19% higher across Medicare Advantage plans than in original Medicare. The Medicare Advantage scores rose by 4 percentage points between 2017 job of identifying who’s actually declining and who’s not,” Langa said.
PROGRESSION
Mild cognitive impairment doesn’t always progress to dementia, nor does it usually do so quickly. But this isn’t well understood. And estimates of progression vary, based on whether patients are seen in specialty dementia clinics or in community medical clinics and how long patients are followed.
A review of 41 studies found that 5% of patients treated in community settings each year went on to develop dementia. For those seen in dementia clinics — typically, patients with more serious symptoms— the rate was 10%. The American Academy of Neurology’s review found that after two years 15% of patients were observed to have dementia.
A sizable portion of patients with mild cognitive impairment — from 14% to 38% — are discovered to have normal cognition upon further testing. Another portion remains stable over time. (This may be because underlying risk factors — poor sleep, for instance, or poorly controlled diabetes or thyroid disease — have been addressed.)
Still another group of patients fluctuate, sometimes improving and sometimes declining, with periods of stability in between.
“You really need to follow people over time — for up to 10 years — to have an idea of what is going on with them,” said Dr. Oscar Lopez, director of the Alzheimer’s Disease Research Center at the University of Pittsburgh. and 2019, faster than the average in past years, he said.
Kronick said that if CMS keeps the current coding adjustment in place, spending on Medicare Advantage will increase by $600 billion from 2023 through 2031. While some of that money would provide patients with extra health benefits, Kronick estimates that as much as two-thirds of it could be going toward profits for insurance companies.
AHIP, the industry trade group, did not respond to questions about the coding controversy. But a report prepared for AHIP warned in September that payments tied to risk scores are a “key component” in how health plans calculate benefits they provide and that even a slight increase in the coding adjustment would prompt plans to cut benefits or charge patients more.
That threat sounds alarms for many lawmakers, according to Kronick. “Under pressure from Congress, CMS is not doing the job it should do,” he said. “If they do what the law tells them to do, they will get yelled at loudly, and not too many people will applaud.”