Neurodegenerative Diseases(ND)

Neurodegenerative diseases are characterised by selective dysfunction and loss of synaptic connectivity and neurons. Dysfunction of glial cells, including astroglia, oligodendroglia and microglia, may have primary roles, or come secondary to neuronal degeneration, or contribute to neuronal degeneration. Neurodegenerative diseases are also characterised by the deposition of conformationally altered variants of physiological proteins in the nervous system that abnormally aggregate in neurons and/or glial cells. The severity and distribution of selective neurodegeneration and functional system affected correlate with the diverse clinical phenotypes observed in patients. In addition, within the same neuropathological entities, anatomical, cytopathological and molecular heterogeneities exist and contribute to the diverse clinical phenotypes observed. Neurodegenerative diseases are traditionally distinguished by the following histological features: 

1. The anatomical distribution and severity of neuronal loss with signs of astroglial and microglial activation correlating with clinical symptoms.

2. Intracellular and/or extracellular filamentous protein deposits detected by antibodies against pathological forms of the protein deposits. 

3. Lack of significant peripheral inflammatory or neoplastic cell infiltration or microbiological agents that could cause neuronal loss. 

4. Lack of evidence for environmental toxic agents contributing to neuronal loss.