Polypathology and Dementia After Brain Trauma: Does Brain Injury Trigger Distinct Neurodegenerative Diseases, or Should They Be Classified Together as Traumatic Encephalopathy?

This volume has already established, in so far as our very limited current knowledge allows, that: (a) brain changes may persist after single concussive brain injuries; (b) brain changes may develop after an apparently asymptomatic period following multiple CBIs; and that (c) survivors of atypical CBIs that have prolonged loss of consciousness appear at higher risk of developing brain changes that have been called “neurodegenerative diseases, " with popular labels such as “Parkinson’s disease” and “Alzheimer’s disease.” Insufficient research has occurred to determine whether single typical CBIs might also increase the risk for delayed-onset encephalopathy. Today’s implausible classification of time-passing-related brain changes makes it more difficult to study the relationship between these observations. The present chapter attempts to bring some coherence to that discussion by reviewing epidemiological studies of encephalopathy after CBI, by considering the long-term influence of post-traumatic neurodegenerative pathologies, and by critically examining the hypothesis that trauma is a risk factor for otherwise conventional dementing illnesses.