Assay of blood-based biomarkers is the trend for assessing/diagnosing neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, dementia with Lewy body, frontotemporal dementia and amyotrophic lateral sclerosis in developing new drug and routine practice. Many ultrasensitive technologies have been developed to precisely measure the pathological biomarkers in blood. This book gives comprehensive introductions to these assay technologies, from the detecting mechanism to pre-clinical performance, ultimately to clinical prospectives and potential challenges in real-world practice.