<prompt> Which of the following are pathological hallmark of Alzheimer;s diseaseIntercellular Lewy BodiesIntracellular Picks BodiesExtracellular Beta Amyloid PlaquesExtracellular Neurofibrillary Tangles  <response>: The two hallmark pathologies required for a diagnosis of Alzheimer;s diseaseAD are the extracellular plaque deposits of the Beta-amyloid peptide Ab and the intracellular flame-shaped neurofibrillary tangles of the Hyper-Phophorylated microtubule binding protein ;tau;. Histological Hallmarks of Alzheimer;s disease: b-Amyloid Plaque Extracellular Neurofibrillary Tangles Intracellular b-Amyloid Neuritic plaques are formed by extracellular accumulation of beta amyloid deposits. ;Neuritic; or ;Senile; b-amyloid plaques are an early histopathological sign of Alzheimer;s disease that occur rarely in healthy subjects The amyloid b-protein accumulated in single Neuritic plaques is toxic to surrounding structures and adjacent neurons. Clinico-pathological studies have shown that amyloid burden does not directly correlate with severity or duration of dementia. Neurofibrillary tangles are formed by intracellular accumulation of hyper-phophorylated microtubule binding protein ;tau; NFT;s occur in many neurodegenerative diseases andor a group of diseases called ;taupathies;. These include Frontotemporal dementia, Pick;s disease etc., The co-occurence of b-amyloid plaques with NFT;s suggests a diagnosis of Alzheimer;s disease AD The NFT;s are toxic to the neurons and neurons with NFT;s eventually die and degnerate leaving a residual ;ghost tangle; in the extramedullary space reminding of the pyramidal cell body in which it was initially formed. Clinico-pathological studies have shown that dementia correlates more strongly with NFT;s than with senile plaques b-Amyloid Ref: Bailey and Love 27th edition 