Diagnostic and therapeutic biomarkers for Alzheimer’s disease in human-derived platelets

Background Diagnosis of current Alzheimer’s disease (AD) is difficult even for medical specialists, and there is no clear biomarker. Also, aging is highly related to the onset of AD. Objectives The purpose of this study is to screen miRNA as an aging-considered biomarker for AD treatment and diagnosis. Methods The patient group for this study was divided into a young normal, old normal, or AD group. We developed a method of discovering sequentially expressed miRNAs to distinguish miRNAs that were sequentially expressed in the three groups. Results Sequentially expressed miRNAs correlated highly with the patient’s age, and most showed expression patterns that distinguished young, old, and AD. Specifically, the miRNA expression we found showed similar patterns in the brains of patients with AD. Among the selected miRNAs, one set derived from the same precursor: The expression of miR-150 was a disease- and age-specific downregulation in both 3p and 5p forms, and the precursor also had the same pattern. We named that triple matching. Also, the found miR-150 precursor had AD-specific miRNA-imbalance characteristics. Conclusions We developed a novel AD diagnostic method using triple matching and miRNA-imbalance. The triple matching and miRNA imbalance-based relative ratio diagnosis method we developed will be very powerful in resolving the challenges of absolute diagnostic quantification based on biomarker expression. Also, our research results suggest the possibility of a treatment target for AD.