Noninvasive Assessment of β‐Secretase Activity Through Click Chemistry‐Mediated Enrichment of Neuronal Extracellular Vesicles to Detect Alzheimer's Disease

Abstract Alzheimer's disease (AD), the most prevalent type of dementia, is characterized by a biological process that begins with the development of AD neuropathologic change (ADNPC) while individuals remain asymptomatic. A key molecular hallmark of ADNPC is the accumulation of amyloid‐β plaques. β‐secretase plays a critical role in the upstream pathological cleavage of amyloid precursor protein (APP), producing amyloid‐β peptides that are prone to misfolding, ultimately contributing to plaque formation. Neuronal extracellular vesicles (NEVs) in the blood transport β‐secretase and preserve its activity, allowing for noninvasive profiling of β‐secretase activity for detecting early onset of ADNPC. In this study, a novel approach is approached for noninvasive assessment of β‐secretase activity in AD patients using an NEV β‐secretase activity assay. This assay identifies NEVs exhibiting colocalization of NEV markers with AD‐associated β‐secretase, generating a β‐secretase activity profile for each patient. The NEV β‐secretase activity assay represents a significant advancement in leveraging the diagnostic potential of NEVs, offering a noninvasive, quantitative method for reliably assessing β‐secretase activity to detect the early onset of ADNPC.