Methods for providing information relevant to diagnosis of neurodegenerative disorder

A method of diagnosing a subject with Alzheimer's disease (AD), comprising:

• obtaining a biological sample containing exosomes from the subject;
• isolating the exosomes from the biological sample;
• determining a level of amyloid beta in the exosomes by using an antibody specific for the N-terminus of amyloid beta, the determining step comprising:
• providing a bead or nanoparticle having a N-terminus-specific antibody immobilized on a surface thereof;
• contacting the isolated exosomes with said bead or nanoparticle;
• and
• measuring an amount of amyloid beta bound to said bead or nanoparticle using an electrochemical impedance spectrometry (EIS) sensor, by measuring an impedance change or current change after the N-terminus-specific antibody reacts with the amyloid beta present in the isolated exosomes;
• obtaining a reference level of amyloid beta present in isolated exosomes from a normal control not having Alzheimer's disease;
• comparing the level of amyloid beta measured in the isolated exosomes from the biological sample with the reference level of amyloid beta present in the isolated exosomes from the normal control;
• and
• diagnosing the subject as having the Alzheimer's disease (AD) if the level of amyloid beta in the biological sample is higher than the reference level of amyloid beta.