A 60-year-old man presents with rapidly progressive dementia, visual hallucinations, fluctuating cognition, and parkinsonism. He has severe neuroleptic sensitivity. Autopsy shows cortical Lewy bodies. The major protein component of cortical Lewy bodies is the same as in Parkinson's disease. Which protein is this?
- A Tau
- B Alpha-synuclein ✓
- C TDP-43
- D Amyloid-beta
Correct answer: B. Alpha-synuclein
Explanation
This describes dementia with Lewy bodies (DLB), the third most common cause of dementia. The core clinical features are fluctuating cognition, visual hallucinations, parkinsonism, and neuroleptic sensitivity. Both cortical and brainstem Lewy bodies are composed of aggregated alpha-synuclein, identical to Parkinson's disease. The distinction from Parkinson's disease dementia is the one-year rule: if dementia occurs within 1 year of motor symptoms, it is DLB. Tau forms neurofibrillary tangles in Alzheimer's. TDP-43 is seen in ALS and some FTD.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.