A retired athlete with Parkinsonian features after years of head trauma is most likely suffering from what underlying condition?

• A. Alzheimer's disease
• B. Stroke
• C. Chronic traumatic encephalopathy
• D. Parkinson disease

Answer: (C)

Repeated head trauma can lead to chronic traumatic encephalopathy, a progressive neurodegenerative tauopathy that often emerges years after exposure. In athletes with a history of repetitive concussions, this condition can present with parkinsonian features such as slowed movement and stiffness, along with behavioral and cognitive changes. The underlying pathology is widespread accumulation of hyperphosphorylated tau in neurons and glia, frequently around small vessels in the depths of the cortical sulci, especially in the frontal and temporal regions. This pattern differs from Alzheimer disease, which centers on amyloid plaques and tau tangles with prominent memory impairment; from classic Parkinson disease, which is primarily a dopaminergic nigral degeneration without a trauma-linked history; and from stroke, which causes focal neurologic deficits that are typically abrupt rather than progressive neurodegeneration after years.