Affordable, Less Invasive Testing for Alzheimer's with Blood-Based Biomarker Tests

This piece previously appeared on the Medical Care Blog.

The Alzheimer’s Association’s 2021 Alzheimer's Disease Facts and Figures report shares that currently, six million Americans are living with Alzheimer’s disease, a number that has increased 145% since the turn of the century. Around the world, there are 50 million people living with Alzheimer's disease or related dementia. Only a quarter of would-be patients are diagnosed. Access to Alzheimer’s disease testing is especially critical for racial and ethnic minorities who are at higher risk of dementia and face discrimination in seeking dementia health care. Moreover, the Administration for Community Living expects the rate of Americans aged 65 and older to exponentially grow, reaching 94.7 million in 2060.

Current State of Alzheimer's Disease Care

Care for Alzheimer's disease faces present and future challenges for both patients and providers. Barriers such as believing cognitive impairment is a normal symptom of aging, stigma related to an Alzheimer's disease diagnosis, and misconceptions related to dementia can impede a patient's access to proper care. Some providers reported confusion of dementia with similar conditions, such as delirium and depression.

Other provider-level factors impacting dementia care include a lack of specialized training programs in geriatric care, and, until recently, insufficient reimbursement rates to cover dementia care. In 2017, The Centers for Medicare and Medicaid Services introduced reimbursement for providers who include a comprehensive dementia care plan for patients. Providers have the opportunity to complete such a care plan during a beneficiary's Medicare Annual Wellness visit, a benefit that became available with the passing of the Affordable Care Act. As of 2018, 48 states and territories have made information regarding early detection, cognitive health, and caregiving publicly available.

However, the United States is presented with a looming threat of a dementia specialist shortage. The Alzheimer's Association estimates that the country currently has half the geriatric providers it needs, and an additional 24,000 geriatricians will be needed in the next nine years. Because of this expected shortage, a quick and affordable test for early detection of Alzheimer’s disease will soon be in high demand.

The History of Biomarker Testing and Dementia Pathology

Biomarker testing is the use of laboratory tests that detect the presence of genetic alterations or mutations in protein expression. One of its uses is to detect dementia and research Alzheimer's disease. Brain imaging and cerebrospinal fluid analysis are currently the most common form of testing. Imaging methods such as CT or MRI scans reveal information on the size of brain structures. Professionals use this data to detect any physical changes or atrophy to these structures. PET scans can detect abnormal levels of glucose and protein in the brain. Similarly, a lumbar puncture used to draw cerebrospinal fluid measures abnormal levels of protein build-up. However, these methods are time-consuming, costly, invasive, and not readily available.

In response to this unmet need for a feasible biomarker test, scientists are developing blood tests to detect heightened levels of beta amyloid plaque. On average, MRI and PET scans can cost up to $8,400 and $3,000, respectively. Blood tests typically cost up to $1,250. Logistically, PET scans are rarely available for would-be patients living in rural areas. Blood testing is more widely available in laboratories.

We can only officially diagnose Alzheimer’s disease at autopsy. However, several key signs point to the neurodegenerative disorder when a person is living. Professionals characterize Alzheimer's disease through the presence of "positive" and "negative" neurodegenerative symptoms. Positive symptoms include a surplus of beta amyloid plaque and tau depositories; negative symptoms include loss of brain neurons and decreased synaptic connectivity. In Alzheimer's disease, beta amyloid plaque, a hardened cluster of protein, builds up in between neurons and interrupts typical function. In healthy adult brains, tau protein is present. However, in Alzheimer's disease, tau forms filaments that get tangled in neurons. Biomarker testing detects excess amyloid plaque.

New Developments for Increased Access to Alzheimer's Testing on the Horizon

Recent scientific developments are bridging the gap between qualifying patients and the unmet need for affordable and less invasive testing. A 2021 study published by C2N Diagnostics, the company credited with creating PrecivityAD, in Molecular Neurodegeneration details results from a blood-based biomarker test for Alzheimer’s disease. The PrecivityAD biomarker test measures levels of beta amyloid plaques. It also identifies the presence of a gene strongly associated with Alzheimer’s disease. The diagnostic performance of PrecivityAD is statistically significant, holding up in comparison to established biomarker tests. A separate 2021 study conducted by C₂N, affirms that the test is highly sensitive in discriminating persons with and without the amyloid pathology. Scientists unaffiliated with C₂N also support the use of blood-based biomarker testing for Alzheimer's disease in conjunction with brain imaging.

In addition to the more cumbersome procedures, Medicare should consider covering blood-based biomarker testing. Especially now, with the recent developments on drugs designed to mitigate Alzheimer's disease. The pressure is on to cover the more accessible blood-based biomarker tests. More patients could be diagnosed and receive treatment. Furthermore, blood tests like these may increase early diagnosis among underrepresented racial groups who are less likely to have access to facilities that can conduct other biomarker testing. Providing coverage to an accessible biomarker test can assist with closing the gap on disparities in dementia health care.