Neurodegenerative Diseases USMLE Step 1 Practice Question
A 66-year-old man presents with rapidly progressive dementia, myoclonic jerks, and gait ataxia over 4 months. Vital signs: BP 138/82, HR 88, RR 16, Temp 37.2°C, SpO2 98%. Neurologic exam shows cogwheel rigidity and hyperreflexia; no focal weakness. EEG demonstrates periodic sharp-wave complexes. MRI reveals cortical ribboning and basal ganglia atrophy. CSF 14-3-3 protein is elevated. Which of the following best explains the underlying pathophysiology of this patient's condition?
Answer choices
- AIntracellular accumulation of alpha synuclein in cortical neurons
- BLoss of cholinergic neurons in the basal forebrain
- CExpansion of a CAG trinucleotide repeat on chromosome 4
- DAutoimmune antibodies to postsynaptic NMDA receptors
- EAccumulation of a misfolded protein that converts normal proteins into beta pleated sheetsCorrect answer
- FLysosomal enzyme deficiency causing glycolipid accumulation in neurons
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