In Alzheimer disease, neurofibrillary tangles are composed primarily of:

• A Alpha-synuclein aggregates forming Lewy body-like fibrils
• B Amyloid-beta peptide (Abeta42)
• C TDP-43 protein aggregates
• D Hyperphosphorylated tau protein forming paired helical filaments ✓

Explanation

Neurofibrillary tangles in Alzheimer disease are intraneuronal cytoplasmic inclusions composed of paired helical filaments (PHF) made of hyperphosphorylated tau protein, a microtubule-associated protein that normally stabilizes microtubule assembly. When tau is hyperphosphorylated, it detaches from microtubules, aggregates into insoluble filaments, and disrupts axonal transport. Alpha-synuclein aggregates form Lewy bodies in Parkinson disease. Amyloid-beta forms extracellular senile plaques, not tangles. TDP-43 aggregates are characteristic of ALS and FTLD-TDP.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.