# Towards Early Diagnosis and Screening of Alzheimer’s Disease Using Frequency Locked Whispering Gallery Mode Microtoroid Biosensors

## TL;DR

This paper introduces a new biosensor that can detect Alzheimer’s disease biomarkers in cerebrospinal fluid with high accuracy, potentially enabling earlier diagnosis.

## Contribution

The first demonstration of using FLOWER biosensors for quantifying Aβ42 in CSF with better diagnostic performance than ELISA.

## Key findings

- FLOWER achieved an AUC of 0.92 for detecting Aβ42 in CSF, outperforming ELISA (AUC = 0.82).
- FLOWER could distinguish between control and MCI samples, indicating potential for early detection.
- The method shows promise for screening CSF for Alzheimer’s pathology with high sensitivity.

## Abstract

Alzheimer’s disease (AD) is a progressive form of dementia affecting almost 55 million people worldwide. It is characterized by the abnormal deposition of amyloid plaques and neurofibrillary tangles within the brain, leading to a pathological cascade of neuron degeneration and death as well as memory loss and cognitive decline. Amyloid beta (Aβ) is an AD biomarker present in cerebrospinal fluid and blood serum and correlates with the presence of amyloid plaques and tau tangles in the brain. Measuring the levels of Aβ can help with early diagnosis of AD, which is key for studying novel AD drugs and delaying the symptoms of dementia. However, this goal is difficult to achieve due to the low levels of AD biomarkers in biofluids. Here we demonstrate for the first time the use of FLOWER (frequency locked optical whispering evanescent resonator) for quantifying the levels of post-mortem cerebrospinal fluid (CSF) Aβ42 in clinicopathologically classified control, mild cognitive impairment (MCI), and AD participants. FLOWER is capable of measuring CSF Aβ42 (area under curve, AUC = 0.92) with higher diagnostic performance than standard ELISA (AUC = 0.82) and was also able to distinguish between control and MCI samples. Our results demonstrate the capability of FLOWER for screening CSF samples for early diagnosis of Alzheimer’s pathology.