Blood tests for Alzheimer’s: progress and limitations

What biomarkers measure, who testing is for, and why test quality matters, including a 2026 FDA update.

15 September 20264 min read

Anna Maria Journal · Development in perspective

Study / event: 16 May 2025 · Explained in perspective

Conceptual illustration: Blood tests for Alzheimer’s: progress and limitations — Conceptual illustration; not experimental data or microscopy.

Key takeaway

Blood biomarkers can support assessment of Alzheimer’s-related changes. Use requires symptoms, clinical evaluation and verification of the particular test and its quality.

An important step with a defined indication

On 16 May 2025, FDA announced US marketing clearance for the Lumipulse G pTau217/β-Amyloid 1-42 Plasma Ratio. The announcement described people aged 55 and older with signs and symptoms. It did not present the test as general screening for people without symptoms.

There is a difference between official sources: technical documentation K242706 accessed on 15 September 2026 specifies age 50 and older. These statements should not be merged into a universal rule. For actual use, the professional checks current product labeling and indications; the historical announcement is insufficient.

U.S. Food and Drug Administration [1]U.S. Food and Drug Administration [2]

What blood measures and what the clinician investigates

This system measures two plasma proteins and calculates the pTau217/β-amyloid 1-42 ratio. It helps assess amyloid pathology. FDA documentation provides negative, positive or indeterminate results. A positive result does not independently establish an Alzheimer’s diagnosis; an indeterminate result may require further investigation within the clinical assessment.

Meanwhile, routine tests and clinical examination have other jobs: investigating different causes of memory difficulties. Thyroid disorders, certain vitamin deficiencies, depression or medication effects can produce similar symptoms. A new biomarker does not replace this broader assessment of what may be contributing to the person’s difficulties.

U.S. Food and Drug Administration [3]Alzheimer’s Association [4]

Scientific progress does not mean absolute certainty

A biomarker needs validation in large, diverse groups using stable measurement methods. Amyloid presence contributes to assessment but does not automatically explain every everyday difficulty. The meaning of a result connects to the history of symptoms and the question that clinicians are trying to clarify.

A 2024 JAMA study assessed 1,213 people with cognitive symptoms in Sweden and found high accuracy for particular biomarkers. It studied methods different from the Lumipulse ratio described here. The authors called for further studies of effects on care; findings do not automatically transfer to every product.

Alzheimer’s Association [5]Palmqvist and colleagues [6]

Where guidelines place these tests

The Alzheimer’s Association guideline for specialist care distinguishes tests that help select patients for further examinations from tests with sufficient performance to confirm pathology. Its recommendations are conditional and based on evidence of low certainty. They concern people with objectively assessed cognitive impairment, within an appropriate clinical setting.

The Association emphasizes that tests are not interchangeable simply because they measure blood biomarkers. Comprehensive clinical evaluation and consideration of the prior likelihood of pathology come first. In practical terms, the precise method and how its result would change assessment belong in the discussion with the specialist.

Alzheimer’s Association [7]Alzheimer’s Association [8]

A quality update that matters

On 15 September 2026, FDA recall Z-1306-2026 remained open, Class 2. Initiated 11 December 2025 and posted 5 February 2026, it concerns β-Amyloid 1-42-N calibrator lots D8C6022U/D8C6044U and falsely elevated positive or indeterminate ratios. Affected lots must be stopped and previous results reviewed where applicable. It does not cover every Alzheimer’s test.

Initial clearance does not end a device’s assessment. FDA describes laboratory diagnostic oversight as a process that also includes quality programs, recalls and safety signals after market entry. Current product information therefore matters alongside the studies supporting its initial use, throughout the device’s clinical life.

U.S. Food and Drug Administration [9]U.S. Food and Drug Administration [10]

Preparing for a useful conversation

If memory is the concern, note specific changes, when they began and which medicines or supplements you take. Bring your questions. You can ask about the purpose of each examination and what an indeterminate answer would mean for the next steps in your assessment and follow-up.

Evaluation may include medical history, physical examination, memory and thinking tasks, and imaging when appropriate. Together, these help clarify the effect on everyday life. A simpler blood draw may make the process easier, but clinical conversation and interpretation remain essential parts of understanding what the results mean.

Alzheimer’s Association [11]Alzheimer’s Association [12]