Answer
Tauopathies are a heterogenous group of neurodegenerative disorders that may culminate in dementia and are characterized by abnormal accumulations of tau protein, often both in neurons and glia (see the image below). [27, 28] Other pathologic hallmarks of brain regions affected by tau pathology are activated microglia, astrocytes, and elevated levels of proinflammatory molecules. [28]
This group of neurogenerative disorders includes corticobasal ganglionic degeneration, the Parkinson-dementia complex of Guam (also called Bodig-Lytigo), and argyrophilic grain disease. Several lines of evidence suggest that AD is also a tauopathy. [28, 29] The clinical presentation of these diseases varies and includes both cognitive impairment and movement disorders. [29, 30]
Dementia pathology. Immunohistochemical staining (brown) against tau at 400× magnification reveals glial immunoreactivity that is characteristic of this case of cortico-basal ganglionic degeneration.
A novel aspect of tauopathies is the potential for cell-to-cell propagation. [30]
-
Dementia pathology. Bielschowsky silver staining of the cortex at 400× magnification demonstrates a neurofibrillary tangle (black arrow) and a neuritic plaque (white arrow).
-
Dementia pathology. Congo red staining of a small cortical artery at 400× magnification demonstrates salmon-colored amyloid deposition in the media of the vessel.
-
Dementia pathology. A: Hematoxylin-eosin-Luxol fast blue staining of the basal ganglia at 100× magnification demonstrates a cavitary infarct. Calcific medial sclerosis of small arteries is also present. B: At 400× magnification, numerous foamy macrophages are present within the center of the infarcted tissue.
-
Dementia pathology. A: Hematoxylin and eosin staining of the substantia nigra at 400× magnification demonstrates multiple Lewy bodies within a pigmented neuron. The Lewy bodies are round with a densely eosinophilic core surrounded by a clear halo. B: Immunohistochemical staining (brown) against alpha-synuclein at 400× magnification reveals a round Lewy body within the soma of a neuron.
-
Dementia pathology. Comorbid brain pathologies are common in the elderly population. This Venn diagram demonstrates the co-occurrence of brain pathologies as evident from population-based autopsy studies of brain aging.
-
Dementia pathology. A: Hematoxylin and eosin staining at 400× magnification of the dentate fascia of the hippocampus reveals round eosinophilic Pick bodies (arrows) in the soma of granular neurons. B: Immunohistochemical staining (brown) against tau at 400× magnification reveals round intraneuronal Pick bodies in cortical neurons.
-
Dementia pathology. A: Hematoxylin and eosin staining at 400× magnification of the cerebral cortex reveals the coalescent clear vesicles characteristic of spongiform encephalopathy. B: Immunohistochemical staining (brown) against protease-resistant prion protein reveals the granular immunoreactivity seen in Creutzfeldt-Jakob disease.
-
Dementia pathology. Immunohistochemical staining (brown) against tau at 400× magnification reveals glial immunoreactivity that is characteristic of this case of cortico-basal ganglionic degeneration.
