Molecular mechanisms of chronic traumatic encephalopathy

The prevalence of neurodegenerative disorders is rapidly increasing. While Alzheimer's disease and dementia generally correlate with longer lifespans, neurodegenerative disorders like chronic traumatic encephalopathy often affect individuals at young age. Historically, the underlying disease mechanisms of these chronic disorders-the slowly changing biochemical composition during aging and the repeated, rapidly changing biomechanical environment during head impact-have been viewed as distinct events. Recent studies suggest that Alzheimer's disease and chronic traumatic encephalopathy share common degenerative pathways on the molecular and cellular levels. Here we examine this current trend and explore the molecular, cellular, tissue, and organ level mechanisms of neurodegeneration through the lens of biomedical engineering. Understanding the underlying disease mechanisms across the spatio-temporal scales of neurodegeneration provides new opportunities to modulate, slow down, and possibly revert molecular dysfunction, axonal death, tissue atrophy, and loss of brain function.