Neuropolypathology as a result of severe traumatic brain injury?

A history of brain trauma has long been acknowledged as increasing an individual's risk of developing dementia in later life. The underlying mechanisms that belie this pre-disposition are, however, very poorly understood. Here, we report a clinical-neuropathological correlation of a man who presented at the age of 66 with a progressive complex atypical dementia with early and prominent neurobehavioral symptoms. His neurological condition continued to decline up to his death at the age of 74. During the compilation of his clinical history, it was established that the subject had experienced a single severe traumatic brain injury (TBI) aged 12 years in 1954 resulting in loss of consciousness, hospitalization, and coma for a number of days after which he was deemed to have recovered. Following post-mortem neuropathological analysis, numerous distinct neuropathologies were observed in various brain regions and these included i) widespread Braak stage VI neurofibrillary tangle formation, ii) widespread α-synuclein positive Lewy bodies and Lewy neurites and iii) diffuse amyloid plaques and severe cerebral amyloid angiopathy (CAA). Added to this, a comprehensive analysis of blood-brain barrier (BBB) integrity, known to be disrupted during and after TBI, showed iv) distinct BBB breakdown with extravasated IgG and activated microglia present. This report represents an interesting documented case of neuropolypathology that may be associated with prior history of severe TBI. We propose one testable theory that a history of brain trauma may be a potential trigger for late onset dementia due to damage and unresolved functioning of the cerebral microvasculature.
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