Traumatic brain injury (TBI) is often considered to be a risk factor for the later development of neurodegenerative conditions, but some findings do not support a link. Differences in research methods, clinical samples, and limitations encountered when assessing and documenting TBI details likely contribute to the mixed reports in the literature. Despite some variability in findings, a review of the literature does provide support for the notion that TBI appears to be associated with earlier onset of some neurodegenerative disorders, although clearly not everyone with a TBI appears to be at an increased risk. Whereas a mechanistic link remains unknown, TBI has been found to initiate an accumulation of pathological processes related to several neurodegenerative disorders. The authors propose a hypothetical model that relates TBI to the development of pathological burden overlapping with some neurodegenerative conditions, in which onset of cognitive/behavioral impairments is hastened in some individuals, but pathological processes stabilize afterward, resulting in a similar course of decline to individuals with dementia who do not have a history of TBI.

Christian LoBue, Ph.D., C. Munro Cullum, Ph.D., Nyaz Didehbani, Ph.D., Kylee Yeatman, B.S., Bruce Jones, Ph.D., Michael A. Kraut, M.D., Ph.D., John Hart, Jr., M.D.
The Journal of Neuropsychiatry and Clinical Neurosciences, October 24, 2017
https://doi.org/10.1176/appi.neuropsych.17070145
https://neuro.psychiatryonline.org/doi/10.1176/appi.neuropsych.17070145

Neurodegenerative Dementias After Traumatic Brain Injury – 2017