Editorial: Unraveling Neuroprotective and Neurodegenerative Signals in Neurodegeneration

Our understanding of the etiology of human neurodegenerative disorders is limited by the necessity to infer an active sequence of events, often expressed over protracted periods of time, from a collection of still-life images that often represent the end of the sequence with no clear view of how we got there. Adding to the collective confusion, it often is not clear whether our measures of nervous system structure and function at a given point in time represent active contributors to degeneration, the tombstones reflecting consequences of degeneration, active attempts to protect the nervous system, products of failed protection, or unrelated events. As a result, we rely on observations and manipulations of fragments of the process in experimental models and human samples, pieced together to create versions of what is possible. In this collection of articles, the iterative process is on full display, with a focus on Alzheimer’s disease, Parkinson’s disease, and related disorders, and reports ranging from tools to mechanisms to treatment.