A method or technique of detecting, diagnosing, monitoring, and evaluating a neurodegenerative disease, such as Alzheimer's disease, in a human body fluid is disclosed. The invention provides for a method of detecting amyloid peptides associated with erythrocytes and amyloid peptide complement complexes, as a diagnostic test for the detection, monitoring, evaluation or diagnosis of Alzheimer's disease and amyloid-based neurodegenerative diseases. More specifically the invention is directed to a method for detecting presence and amount of amyloid peptides such as amyloid beta (“Aβ”) and Aβ complement complexes, and related complement complexes and compounds with a role in neurodegenerative diseases, in an erythrocyte fraction of a human bodily fluid.