On Aug. 14, 2026, FDA approved Tauklarify (florquinitau F 18 injection, formerly MK-6240) for brain PET in adults with cognitive impairment being evaluated for Alzheimer's to identify tau tangle pathology, according to Lantheus in the FDA approval notice. Accuracy was stronger for ruling tau out than ruling it in, the label sets firm limits, and practical access details remain missing for younger-onset families weighing testing.
Tau PET imaging shows tau neurofibrillary tangles, twisted tau proteins that collect inside brain cells and track with Alzheimer's decline. For families facing memory, thinking, or behavior changes before age 65, the question is rarely Alzheimer's or nothing. Frontotemporal dementia, mood disorders, sleep disorders, and other causes can look similar. A tau scan can add one biological clue, but it cannot settle the diagnosis alone.
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.
Official resources:
- Read the official notice from Lantheus — Use this primary source to verify the official announcement.
- Read the official notice from Neurologylive — Use this primary source to verify the official announcement.
Table of Contents
- How accurate is the scan?
- What are the hard limits?
- Why does this matter for younger-onset families?
- What should you do before seeking the scan?
How accurate is the scan?
Approval rested on two studies where five blinded readers classified scans against a cognition-plus-amyloid-PET reference, with positive agreement of 68-88 percent and negative agreement of 93-99 percent across readers, as reported by NeurologyLive in the NeurologyLive accuracy report. That pattern means a negative read was usually right, while a positive read needed clinical follow-up. Readers agreed with each other well. The same report described Fleiss kappa values of 0.92 and 0.86, which supports consistent tau-positive versus tau-negative calls across centers.
Consistency helps families who seek second opinions or change clinics. A head-to-head study added useful context. In the prospective HEAD study, MK-6240 separated Alzheimer's-related impairment better than Tauvid, with AUC 0.93 versus 0.86, and found about 15 extra tau-positive mild cognitive impairment cases and 21 extra dementia cases per 100 tested, according to Being Patient describing The Lancet results in the Being Patient report on the HEAD study. Mild cognitive impairment means measurable thinking changes that do not yet remove independence.
What are the hard limits?
FDA labeling limits use to Alzheimer's evaluation because safety and effectiveness are not established for non-Alzheimer tauopathies, and performance may be lower at earlier pathologic stages, as summarized by Pharmacy Times in the Pharmacy Times labeling summary. That matters when symptoms are new, mild, or point toward another tau disease. Labeling also warns that a negative scan does not exclude tau pathology and a positive scan does not confirm it. Clinicians should pursue added testing when doubt remains.
For families, the practical point is direct: keep the broader workup going after the scan. Side effects in the approval record were uncommon. In 1,734 exposed subjects, headache occurred in 0.7 percent and nausea in 0.2 percent. Labeling also advises radiation precautions, avoiding CYP1A2 inducers and smoking for seven days, and pausing breastfeeding for four hours.
Why does this matter for younger-onset families?
Younger workers and parents often face job, driving, childcare, and money choices while evaluation is still open. A clear tau-negative result can reduce one source of fear and push attention toward treatable causes, mood, sleep, medications, or another dementia. A tau-positive result points back to Alzheimer's-focused care planning, not to a final answer by itself. Tau information also joins amyloid information.
As only the second FDA tau tracer after Tauvid, Tauklarify complements amyloid PET to clarify complex cases and guide anti-amyloid decisions. Anti-amyloid drugs target amyloid plaques, while tau scans show a different Alzheimer's protein, so the two tests answer different questions. Timing remains uncertain. Commercial availability timing is undisclosed. Families should ask a memory clinic whether the tracer is offered locally, what it costs, and whether insurance covers it for their exact indication.
What should you do before seeking the scan?
Bring a complete symptom timeline, work impact notes, medications, sleep history, family history, and prior brain scans or spinal fluid results. Ask whether amyloid testing already answers the next treatment question. Ask what the team will do differently after a positive, negative, or unclear tau result.
- Confirm the indication is cognitive impairment being evaluated for Alzheimer's disease.
- Ask about smoking, CYP1A2 inducer drugs, pregnancy, and breastfeeding rules.
- Plan for radiation safety instructions after injection.
- Arrange time off, transport, and childcare for the visit and follow-up.
- Request a written plan for added testing if the scan and clinic picture disagree.
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