LabCorp’s Beta-Amyloid 42/40 Ratio test quantifies the amount of beta-amyloid 42 and 40 proteins in a CSF patient sample and computes the ratio of those proteins, providing an indication of disease progression. Studies have shown strong correlation of CSF beta-amyloid levels to PET scan results. This test can be a surrogate to more costly PET scan imaging.

This test detects the presence of the Apolipoprotein E (APOE)-4 variant, which is associated with increased risk of late-onset (age >60-65) Alzheimer's disease (AD). Testing may be considered for patients with dementia to supplement information from clinical and other evaluations. APOE has multiple roles, including lipid transport in the blood and the brain. The APOE4 variant increases the risk for late-onset Alzheimer's disease and may contribute to the pathology of the disease through influence on β-amyloid, inflammation, or other processes.

AD is a complex and heterogeneous disease, influenced by many genetic and environmental factors. Early onset familial AD (presenting between 25-60) occurs in less than 2% of AD cases. This test analyzes three genes (amyloid protein precursor (APP), presenilin 1 (PSEN1) and presenilin 2 (PSEN2)) to detect pathogenic variants that cause autosomal dominant early onset Alzheimer's disease. Testing may be considered to confirm a diagnosis of early onset Alzheimer's disease in symptomatic individuals.