Blood Test for Alzheimer’s

KathyF1

My DH has a test last week- Quest Ptau 181. It came back at 1.19 where anything higher than 1.07 indicates Alzheimer’s. Was wondering if anyone else has experience with this test?

Gator1976

My wife was diagnosed a month ago after a year (most of 2024) having many tests preformed including brain scan, spinal fluid evaluation, driving test, memory testing, sleep testing, psychological testing and various follow ups including a recasting of her memory before we were told. Her neurologist explained no one test is a conclusive test for Alzheimer’s. Each one is an indicator. The more indicators pointing the same direction is a more reliable diagnosis for this horrible disease. I highly suggest not relying on one test but doing more testing before coming to a conclusion.

Leesee

My DH was diagnosed with Alzheimer's using the Quest ABETA 42/40 RATIO test in Dec. 2023.

I am very interested in the test your DH had and did a quick search.

A Google comparison between the the Quest ABETA test and the Quest p tau 181 follows:

When comparing Quest's P-tau 181 test to the Abeta 42/40 ratio, both are used as biomarkers for Alzheimer's disease, but the P-tau 181 test specifically measures a phosphorylated form of the tau protein, indicating neuronal damage, while the Abeta 42/40 ratio looks at the balance between two amyloid beta protein fragments, with a lower ratio suggesting a higher risk of Alzheimer's pathology; essentially, P-tau 181 is more indicative of tau pathology while the Abeta 42/40 ratio reflects amyloid beta plaque deposition. 

Both biomarkers are associated with Alzheimer's disease, but a higher P-tau 181 level is generally considered a stronger indicator of neurodegeneration, while a lower Abeta 42/40 ratio is linked to increased amyloid plaque formation.

Often, both tests are used together for a more comprehensive picture of Alzheimer's disease pathology, as they provide information about different aspects of the disease process. 

Additionally, Quest's website states: https://testdirectory.questdiagnostics.com/test/test-guides/TS_AD_Detect_Ptau181Plasma/quest-ad-detect-phosphorylated-tau181-p-tau181-plasma?p=td

Increased plasma p-tau181 levels can also predict clinical progression to more severe cognitive impairment. Furthermore, plasma p-tau181 can differentiate AD from many other neurodegenerative diseases, such as frontotemporal dementia, vascular dementia, and Parkinson disease

Looking at this information It appears the p-tau 181 will provide us with the level (stage) of Alzheimer's. I'm going to ask DH's doctor for the p-tau test. There is some indication this test may not yet be covered by insurance, the the cost to self-pay is $200-$500.

Thank you so much for bringing this test to our attention!

KathyF1

Thanks for your replies, my husband is actually in Stage 6, the neurologist ordered the blood test because he said my husband has Frontotemporal not Alzheimer’s. He wanted to rule out Alzheimer’s. He has all the symptoms of Alzheimer’s though AND the symptoms of Frontotemporal (behavior variant). I’ve read that yes they can have both. I was not surprised to see the blood test come in positive for Alzheimer’s.

Leesee

My DH's first diagnosis was also FTD. A follow-up MRI showed he actually had Vascular Dementia with the majority of damage to the frontal and temporal lobes.

ALZ and VD are often found together, so the diagnosis of VD led to the ABETA blood test confirming he has both (mixed dementia).

I'm sorry to hear your DH is in stage 6, but this is such important information. I didn't know there was a test to help identify the stage. I'm almost afraid to request the test (my own denial) but this is the piece that has been missing.