I remember a patient in her early sixties who came to our clinic with subtle memory problems. She lived alone in a rural county, relied on Medicaid, and had been passed between social services and different primary care providers for more than a year. No one had ordered imaging, and there were no neurologists nearby. By the time Alzheimer’s disease was suspected, her window for early intervention had already closed.
Medicare recently expanded coverage for amyloid PET scans, giving more patients a path to earlier diagnosis. But for the millions of people covered by Medicaid, especially those at highest risk, access to even the most basic diagnostic tools remains limited. Blood-based biomarker tests are now clinically validated and increasingly available, yet most Medicaid programs have not updated their coverage to reflect this shift. That policy gap delays diagnosis and narrows treatment options.
Plasma biomarkers such as the Aβ42/40 ratio, phosphorylated tau (p-tau181), glial fibrillary acidic protein (GFAP), and neurofilament light chain (NfL) can detect early changes in Alzheimer’s disease with a high degree of accuracy. These tests are less invasive than spinal fluid analysis, more affordable than PET imaging, and easier to use in primary care settings. They have become even more critical with the emergence of new disease-modifying treatments like lecanemab and donanemab, both of which require biomarker confirmation before use.
In May 2025, the FDA cleared the first Alzheimer’s blood test through the substantial equivalence pathway, recognizing it as comparable to existing diagnostic methods. Despite this milestone, most Medicaid programs have not incorporated these tests into their coverage frameworks. A review of all 51 state Medicaid programs found that only 18 mention Alzheimer’s blood tests in their public coverage documents. Fewer than half include billing codes, and very few acknowledge the access barriers faced by medically underserved patients. Meanwhile, PET scans and spinal fluid tests are still covered in most states, even though they are often more expensive and less accessible, particularly in rural areas.
This disconnect reinforces long-standing disparities in care. Black and Hispanic adults are more likely to be insured through Medicaid, more likely to develop Alzheimer’s, and more likely to experience delayed diagnosis. When lower-cost, clinically appropriate diagnostics are excluded from coverage, these inequities grow even deeper.
Some states have started to take steps. In 2024, Florida passed legislation requiring Medicaid to cover Alzheimer’s blood tests. While implementation will vary across care settings, the clinical rationale is clear. However, without federal guidance, most states have not acted. Diagnostic access now depends less on medical need and more on location.
To close the gap, the Centers for Medicare & Medicaid Services should issue formal guidance supporting coverage of FDA-cleared blood-based diagnostics. States can then establish consistent billing practices and implementation strategies that prioritize access from the beginning rather than waiting until disparities emerge.
We already have the tools to identify Alzheimer’s earlier, more affordably, and in a way that reduces the burden on both patients and providers. The real obstacle is not technology, it’s policy. Clinicians and caregivers continue to see the effects of delayed diagnosis, especially in communities with limited access to specialty care. Medicaid programs have an opportunity to address this problem directly. Patients should not be denied timely diagnosis simply because their insurance hasn’t kept up with the science.
Amanda Matter is a doctor of pharmacy student.
