Primary-care doctors who reviewed the PrecivityAD2 blood test raised diagnostic accuracy from 65% to 93%, nearly matching specialists at 94%. The finding comes from a Swedish study of 1,310 patients seen by 165 physicians, reported by the Alzheimer's Association in its AAIC 2026 research summary. PrecivityAD2 is a blood test for Alzheimer amyloid pathology.
It measures amyloid-beta Aβ42/Aβ40 plus p-tau217 ratios. The FDA cleared it on Aug. 20, 2026 for adults 40 and older with cognitive signs, for use with clinical assessment, according to the FDA clearance notice from the Alzheimer's Association.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Table of Contents
- Which blood test did the study use?
- How did results change care?
- Who qualifies for the FDA-cleared test?
- When is PET or spinal fluid testing still needed?
- What should you bring to a memory visit?
Which blood test did the study use?
The AAIC 2026 primary-care analysis used C2N Diagnostics' PrecivityAD2. According to Clinical Lab Products, the test combines amyloid-beta Aβ42/Aβ40 and p-tau217 ratios. Those ratios signal amyloid buildup in the brain.
Amyloid buildup is a defining pathology of Alzheimer's disease. The blood result is therefore a pathology marker, not a memory score. Physicians reviewed the result alongside history, exam, and cognitive testing. The study tested aided diagnosis, not blood testing alone.
How did results change care?
After seeing PrecivityAD2 results presented July 14, 2026 in London, physicians changed planned management in over 60% of cases. Medscape Medical News reported revised diagnoses in about one-third of cases. A change could mean a different diagnosis, different medication review, or different follow-up plan.
It could also mean counseling about safety, driving, and support needs. The point is that the result altered the next clinical move. For primary care, the test was most helpful for ruling out Alzheimer's. C2N Diagnostics, via BioSpace, said this helps avoid unnecessary specialist referrals while identifying who needs further workup.
Who qualifies for the FDA-cleared test?
Clearance covers adults 40 and older with signs or symptoms of cognitive impairment. It is an aid alongside clinical assessment. It is not screening and not a standalone diagnosis.
Earlier FDA-cleared blood tests were narrower, according to AJMC. Fujirebio Lumipulse p-tau217/Aβ42 was cleared in May 2025 for ages 55 and older in specialty evaluation, while Roche Elecsys p-tau181 helps rule out Alzheimer's. Ask your clinic these checks before testing:.
- Do I have new, persistent memory or thinking symptoms noted on exam?
- Am I 40 or older and being evaluated for possible impairment?
- Will the doctor interpret the result with my history and cognitive testing?
- What follow-up is planned if the result is positive, negative, or unclear?
When is PET or spinal fluid testing still needed?
Kidney dysfunction can confound results. Even mild impairment can raise Alzheimer blood biomarkers and cause false positives requiring PET or CSF confirmation, according to the Vanderbilt University Medical Center report. Practical guidance sets a high bar for replacement.
Patient Care Online, reporting on the Alzheimer's Association guideline, said tests need at least 90% sensitivity and 90% specificity to replace PET or CSF. Many commercial tests do not meet those thresholds. Treatment eligibility often still requires PET or CSF confirmation. A positive blood test alone does not settle access to Alzheimer drug therapy.
What should you bring to a memory visit?
Bring specific examples of recent changes. Note missed bills, repeated questions, getting lost, or trouble managing medications. Bring a full medication list and medical history, including kidney disease. Ask what test brand the clinic uses.
Ask whether that test meets high-accuracy thresholds. Ask how a low-risk result changes referrals and how a high-risk result leads to confirmatory testing. Write down the planned next step before you leave. A clear plan may be watchful follow-up, brain imaging, spinal fluid testing, or specialist referral.
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