Elecsys^® β-Amyloid (1-40) CSF

Alzheimer's disease (AD) is the most common cause of dementia, a progressive neurodegenerative disorder that severely impacts memory and cognition.¹ In 2021, an estimated 57 million people worldwide were living with dementia, projecting a massive rise that creates a significant global healthcare and economic burden.¹ As the seventh leading cause of death globally, the substantial costs of caregiving strain both health systems and families.¹

AD is characterized by the accumulation of ß-amyloid (Aβ) plaques and tau protein tangles in the brain. Early symptoms are often nonspecific and overlap with other conditions, making a timely and accurate differential diagnosis challenging.¹ Given the sheer number of affected individuals and the intensive long-term care required, AD represents one of the most pressing public health challenges worldwide.

For effective patient management and access to new disease-modifying therapies, a definitive diagnosis is crucial. This is achieved by measuring specific cerebrospinal fluid (CSF) biomarkers and the following ratios: Aß42, Aß42/Aß40 ratio, total Tau (t-Tau), phosphorylated Tau (p-Tau), and the p-Tau/Aß42, t-Tau/Aß42 ratios.²

Relying on single Aβ42 concentrations can be problematic due to analytical and pre-analytical variability.³ Ratio biomarkers, however, significantly improve diagnostic accuracy and concordance with positron emission tomography (PET) imaging.^3,4 Assays that utilize single, validated cut-offs for ratios offer superior clarity and confidence in confirming amyloid pathology.
 

• Aβ42/Aβ40 Ratio: This ratio is superior to Aβ42 alone for detecting brain amyloid deposition, even in the prodromal stage of AD, and for differentiating AD from other dementias.^3,4
• pTau/Aβ42 and tTau/Aβ42 Ratios: Normalizing Tau markers to Aβ42 enhances diagnostic performance. These ratios provide a reliable method to confirm both core pathological changes, amyloid and tau proteinopathies—hallmarks of Alzheimer's Disease—showing slightly stronger concordance with amyloid PET.⁵

Accurate, reliable CSF assay results, powered by these ratios and a single cut-off, give clinicians the definitive diagnosis with confidence needed for optimized patient care and clinical trial recruitment.⁴

This is the power of clarity, built on a foundation of trust.