Ab40 Oligomers Identified as a Potential Biomarker for the Diagnosis of Alzheimer’s Disease

Alzheimer’s Disease (AD) is the most prevalent form of dementia worldwide, yet the development of therapeutics has been hampered by the absence of suitable biomarkers to diagnose the disease in its early stages prior to the formation of amyloid plaques and the occurrence of irreversible neuronal damage. Since oligomeric Ab species have been implicated in the pathophysiology of AD, we reasoned that they may correlate with the onset of disease. As such, we have developed a novel misfolded protein assay for the detection of soluble oligomers composed of Ab x-40 and x-42 peptide (hereafter Ab40 and Ab42) from cerebrospinal fluid (CSF). Preliminary validation of this assay with 36 clinical samples demonstrated the presence of aggregated Ab40 in the CSF of AD patients. Together with measurements of total Ab42, diagnostic sensitivity and specificity greater than 95 % and 90%, respectively, were achieved. Although larger sample populations will be needed to confirm this diagnostic sensitivity, our studies demonstrate a sensitive method of detecting circulating Ab40 oligomers from AD CSF and suggest that these oligomers could be a powerful new biomarker for the early detection of AD