Trauma (Slow onset, progressive)
Classical history of repetitive head injury, usually as a consequence of playing contact sports. Concussion is a major risk factor.
Definitive diagnosis at autopsy – reveals deposition of neurofibrillary tangles, mainly in the cortex.
Recurrent head trauma causes diffuse neuronal injury and loss, scarring, and tau protein deposition.
Cognitive impairment, mood disorders, changes in personality and behavior, parkinsonism, and gait and speech abnormalities are common.