AD-Detect Test for Alzheimer Disease
Quest Diagnostics started offering its AD-Detect Test for Alzheimer Disease in 2023. Consumers can purchase the test for $399 plus a $13 physician service fee. The test utilizes liquid chromatography-tandem mass spectrometry to measure the ratio of two amyloid beta peptides, 42 and 40, in plasma (the amyloid beta 42:40 ratio).
The reference range for amyloid beta 42:40 ratio is 0.170 or greater. Quest Diagnostics divides AD-Detect results into three ranges suggesting lower, intermediate, and higher risks of having Alzheimer disease pathology:
- Aβ42/40 ratio ≥0.170 suggests a lower risk of having AD pathology compared to lower values and may prompt investigation of non-AD causes of mild cognitive impairment or dementia.
- An Aβ42/40 ratio of 0.150 to 0.169 suggests an intermediate risk of having AD pathology. Follow-up testing, such as a PET scan or CSF biomarkers, may be warranted to investigate Alzheimer pathology.
- An Aβ42/40 ratio <0.150 suggests a higher risk of having AD pathology and may suggest that follow-up testing (PET, CSF biomarkers) is warranted to investigate AD pathology as the cause of mild cognitive impairment or dementia.
Compared to amyloid PET scan, a Quest study of 209 individuals found that an amyloid beta 42:40 ratio of 0.160 had a sensitivity of 89% and specificity of 71% for detecting amyloid deposits.
To order the test, individuals must acknowledge they have mild cognitive impairment decline and at least one additional risk factor. The Quest Health web site informs them that AD-Detect is intended for anyone who suspects they may have Alzheimer disease, has a positive family history of the disease, has a genetic predisposition to Alzheimer disease, has previously been diagnosed with brain trauma or a head injury, or is experiencing memory loss or early cognitive decline.
Consumers can discuss their results with a network of internists who are independent contractors with Quest. AD-Detect is a laboratory developed test and has not been approved by the FDA.
References
Rubin R. Consumers can now buy a blood test to evaluate their Alzheimer disease risk, but should they? JAMA Oct 3, 2023;330:1214-15.
