Neuritic pathology with

FIGURE 12—14. Postmortem brain pathology defines what Alzheimer s disease is. Shown here are abnormal degenerative structures called neuritic plaques with amyloid cores. 

Calingasan NY, Gandy SE, Baker H, Sheu KF, Smith JD, Lamb BT, Gearhart JD, Buxbaum JD, Harper C, Selkoe DJ, Price DL, Sisodia SS, and Gibson GE (1996) Novel neuritic clusters with accumulations of amyloid precursor protein and amyloid precursorlike protein 2 immunoreactivity in brain regions damaged by thiamine deficiency. American Journal of Pathology 149,1063-71. 

Abundant neuritic plaques and neurofibrillary lesions define Alzheimer s disease. Plaques are extracellular deposits made of the fibrillar P-amyloid peptide. The paired helical filament (PHF) makes up the bulk of the intraneuronal neurofibrillary pathology of Alzheimer s disease, with the straight filament (SF) being a minority species. 

The degenerative process of idiopathic PD (iPD) is associated with the anatomical progression of CEBl-synuclein into select neurons. It is an aggregate of the mis-folded protein and appears in dendrites and axons, Lewy neurites (LNs), as well as punctuate structures and/or Lewy bodies (LBs) in the somata of involved nerve cells. It is thought that only projection neurons with a long axon become involved, whereas short-axoned cells resist the pathology. It has been proposed that vulnerable brain regions in PD are anatomically interconnected. 

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