Neurodegenerative disorders are a set of slowly evolving neuropathological conditions with progressive loss of function and eventually death of neurons participating in motor, sensory or cognitive functions, including for example Alzheimer's, Parkinson's, Huntington's diseases, and amyotrophic lateral sclerosis. Multifaceted factors contribute to the symptoms and progression rate of neurodegeneration, like onset age, sex, and polygenic risk factors. Recent evidence supported a broad range of protein-protein interactions with substantial contribution beyond the above factors to the symptoms and progression rate of neurodegeneration. However, previous evidence was all derived from invasive experiments on human tissues or model animals. The feasibility of mapping these protein-protein interactions using minimally invasive experiment has not been examined. To address this issue, we plan to estimate protein-protein interactions using cerebrospinal fluid proteomic data from Parkinson's and Alzheimer's diseases and examine their feasibility of tracking disease progression.