Reviewed by the Help Dementia Editorial Team — our editors review every article for accuracy against guidance from the National Institute on Aging, the Alzheimer’s Association, and peer-reviewed sources.
Yes, new diagnostics are expanding treatment access—but not uniformly. Companion diagnostics developed alongside therapeutics are opening doors to precision medicine in neurology, immunology, and brain health conditions that previously had limited treatment options. Since 2016, the FDA has granted over 1,200 Breakthrough Device designations, accelerating the approval and availability of diagnostic tools that unlock access to targeted treatments.
For dementia and neurodegenerative diseases, this means earlier identification of biomarkers that predict which patients will respond to emerging therapies, and faster pathways from diagnosis to treatment. The numbers tell a clear story: new diagnostic product launches rose 42% year-over-year, with AI biomarker tools expanding by 33% and multi-biomarker panels growing by 31%. Yet access remains deeply unequal. While diagnostics are proliferating, rural patients, lower-income populations, and traditionally underserved communities still face significant barriers to obtaining these tests—meaning the expansion of treatment access is real, but incomplete.
Table of Contents
- How Are Diagnostics Reshaping Which Treatments Become Available?
- The Rapid Expansion of Biomarker Testing and Its Limits
- AI and Miniaturization: The Next Wave of Diagnostic Access
- Targeting Underserved Populations with Better Diagnostics
- Disparities in Biomarker Testing Access Remain a Persistent Challenge
- How FDA Approvals Are Accelerating Diagnostic Innovation
- From Lab Result to Treatment: The Critical Gap
How Are Diagnostics Reshaping Which Treatments Become Available?
Companion diagnostics are no longer an afterthought in drug development. The FDA increasingly endorses co-development models where a diagnostic test is built into the approval pathway for a new therapy from the start. This approach has accelerated approvals for treatments that depend on identifying specific biomarkers. In 2025, accelerated approvals for lung cancer treatments like Zongertinib and Sunvozertinib all required companion biomarker testing to determine which patients would benefit.
For Pembrolizumab in platinum-resistant ovarian cancer, the approval itself is tied to the PD-L1 IHC 22C3 pharmDx companion diagnostic test—meaning patients cannot access the drug without first having the diagnostic test performed. For brain health and dementia, this model is still developing but gaining traction. As blood biomarkers for Alzheimer’s disease and other neurodegenerative conditions become more refined, companion diagnostics are being positioned to identify patients most likely to benefit from emerging immunotherapies and disease-modifying drugs. The benefit is real: patients get tested only for the biomarkers that matter for their specific condition, and treatments can be approved faster because safety and efficacy have been demonstrated in a biomarker-defined population. The drawback is that access to the diagnostic test becomes a gatekeeper—if you cannot get the test, you cannot access the treatment.
The Rapid Expansion of Biomarker Testing and Its Limits
Over 45% of newly approved diagnostic tools now incorporate biomarker components, reflecting a fundamental shift toward precision medicine. High-throughput sequencing, proteomics, and metabolomics are enabling discovery of novel biomarkers faster than ever before. Yet the diagnostics market is growing unevenly. AI biomarker tools expanded 33%, and digital diagnostic platforms increased 25%, but these advances are concentrated in settings with access to sophisticated lab infrastructure, data systems, and trained personnel.
For patients in rural areas or small towns, the bottleneck is often not the existence of a diagnostic test but the availability of a facility capable of running it. Point-of-care and decentralized testing technologies are supposed to solve this problem by bringing diagnostics closer to patients outside traditional lab settings. A fingerstick blood test for Alzheimer’s biomarkers, for example, could theoretically be performed in a primary care clinic—but only if the clinic has the equipment, training, and reimbursement to support it. Current reality lags behind the promise: many primary care practices still lack access to these tools, and insurance coverage for newer biomarker tests remains inconsistent.
AI and Miniaturization: The Next Wave of Diagnostic Access
Artificial intelligence is taking on a more active role in diagnostic interpretation and lab workflow management. Rather than simply automating routine tasks, AI is being deployed for multi-modal phenotyping—combining multiple data sources to paint a richer picture of a patient’s condition and predict treatment response. In research settings, this is proving effective at identifying patient subgroups who might benefit from treatments that conventional analysis would miss.
Miniaturization of diagnostic technologies is advancing patient-driven diagnostics with real-time insights, potentially allowing patients to receive results within hours rather than days. A decentralized model where a patient’s primary care provider or neurologist performs or orders a rapid biomarker test, receives AI-interpreted results, and discusses treatment options immediately is becoming technically feasible. For someone with suspected cognitive decline, this could mean a clear path from first symptom to diagnosis to treatment discussion within weeks instead of months. However, the clinical validation of these tools is still ongoing; not all AI-assisted diagnostics have been prospectively validated in diverse populations, and regulatory pathways for some newer technologies remain unclear.
Targeting Underserved Populations with Better Diagnostics
Adaptive trial designs and point-of-care assays are emerging as tools to expand equitable adoption of diagnostic testing. Some research groups are specifically working to deploy multi-biomarker testing in underserved communities, recognizing that biomarker-driven precision medicine will only widen disparities if access depends on affluence or geography. One concrete example: programs that partner with federally qualified health centers (FQHCs) to bring blood biomarker testing for neurodegenerative diseases into primary care settings in low-income neighborhoods, using simplified workflows and community health worker support.
The model is promising but resource-intensive. Expanding access to diagnostics in underserved areas requires more than just technology—it requires training, infrastructure investment, and often upfront funding to demonstrate ROI before insurance companies will reimburse. A rural clinic in Mississippi might have the same diagnostic technology as a major medical center, but without local expertise in interpreting results and counseling patients about treatment options, the diagnostic becomes less useful. Federal and foundation funding for these programs exists but is limited and project-based rather than sustained.
Disparities in Biomarker Testing Access Remain a Persistent Challenge
Current disparities in biomarker testing access persist for lower-income patients, rural and underserved areas, and traditionally underserved populations. This is not a new problem, but it has been thrown into sharper relief as diagnostics have advanced. A patient with early Alzheimer’s pathology who lives in an affluent suburb with a memory care specialist might have access to multiple blood biomarker tests, amyloid PET imaging, and a clear diagnosis by age 60. An equally affected patient living in a rural area or low-income urban neighborhood might not receive any biomarker testing, making it harder to distinguish Alzheimer’s from other causes of cognitive decline and delaying access to disease-modifying treatments.
Insurance coverage disparities compound the problem. Tests that are readily covered by private insurance may be denied to Medicaid beneficiaries, or may require prior authorization that delays diagnosis and treatment. Some insurance plans cover only specific biomarker tests, not the panel that a neurologist would ideally use. For uninsured patients, the out-of-pocket cost of a comprehensive biomarker panel can be prohibitive, even when the technology exists locally.
How FDA Approvals Are Accelerating Diagnostic Innovation
The FDA’s Breakthrough Device Designation program is helping speed approval for diagnostics that address serious conditions. As of March 31, 2026, the FDA has granted 1,284 total Breakthrough Device designations, with over 1,200 devices designated since 2016—many powered by AI. In February 2026, NG Biotech’s NG-TEST Candida auris and NG-TEST Acineto-5 received Breakthrough designations for rapid infectious disease diagnostics addressing life-threatening conditions.
While those examples are in infectious disease, the same acceleration pathways are being used for neurological and neurodegenerative diagnostics. Faster FDA approval means diagnostics can reach clinical practice sooner, and earlier availability can lead to earlier treatment access for qualifying patients. However, Breakthrough designation does not guarantee reimbursement, insurance coverage, or widespread clinical adoption. A diagnostic test approved by the FDA is still useful only if clinicians know about it, can order it, get timely results, and have treatments to offer based on those results.
From Lab Result to Treatment: The Critical Gap
A diagnostic result is only as valuable as the treatment options that follow. The expansion of diagnostics without parallel expansion of effective treatments can create a situation where patients receive a diagnosis but have limited options for what to do about it. In dementia, for example, blood biomarkers can now identify amyloid and tau pathology years before symptoms appear, but disease-modifying treatments remain limited and available only to patients who meet specific criteria.
Point-of-care testing and decentralized diagnostics are closing the geography gap, but they do not automatically close the treatment gap. A primary care provider in a small town can now order a blood biomarker test for Alzheimer’s and receive results in days—a genuine expansion of access. But if that provider cannot then access specialized neurology care, infusion centers for monoclonal antibody therapies, or cognitive rehabilitation services, the diagnostic result alone may not translate into expanded treatment access. True expansion of treatment access requires diagnostics, treatments, infrastructure, and care coordination to advance together.
