Dementia

Dementia is a syndrome associated with continued decline in brain function resulting from an undesirable change in the chemistry and structure of nerve cells.

Signs and symptoms of dementia occur when neurons or cells once healthy nerves in the brain stop functioning, lose their connections with other brain cells, and die. There are many causes of dementia, including the most common are dementing proteinopathies and vascular dementia.

Proteinopathy also known as protein conformation disorder proteins, refers to the tendency of specific proteins to accumulate and deposit abnormally in the brain, often in specific neuropathological structures. The progressive accumulation of protein deposits in vulnerable regions of the brain and their interaction with many molecules in the extracellular space(cell surface receptors, metals, cell membranes, etc.) triggers a complex cascade of events involving oxidative stress, mitochondrial diffusion, inflammation, excitotoxicity, and synaptic dysfunction. These events cause progressive degeneration and death of nerve cells.

Several diseases belong to this category mainly Alzheimer disease, characterized by the formation of two types of protein aggregates: neuritic plaques and degenerations neurofibrillary cells consisting respectively of amyloid beta (Aβ) and the hyperphosphorylated tau protein, Lewy body dementia associated with abnormal deposits of the synuclein protein called Lewy bodies, Frontotemporal dementia caused by inclusions of several proteins [Tau, TDP 43 (TAR 43 DNA-binding protein) and FUS (FUS/TLS RNA-binding protein)] and human transmissible spongiform encephalopathies (TSEs) caused by the accumulation of the prion protein (PrPsc).

Vascular dementia is another common type of dementia that refers to a neurocognitive disorder resulting from multiple cerebrovascular impairments, most often linked to major cerebrovascular accidents and small vessel disease. The clinical manifestations of vascular dementia may vary depending on the size, the location, and the type of brain lesion.

The pathophysiology of vascular dementia is complex and involves several mechanisms, including reduction of blood flow to the brain, alteration of oxygen metabolism, and inflammatory mechanisms. Cognitive decline can develop gradually, in stages, or by a combination of the two.