Minimal neuropathologic diagnosis for brain banking in the normal middle-aged and aged brain and in neurodegenerative disorders.

Research on human brain diseases is currently often conducted on cell cultures and animals. Several questions however can only be addressed by studying human postmortem brain tissue. However, brain tissue obtained postmortem almost always displays pathology that is often related to the aging phenomenon. Thus, in order to be certain that the answers obtained are reliable, a systematic and thorough assessment of the brain tissue to be studied should be carried out. We are currently aware of several protein alterations that are found in middle-aged and aged brains that are obtained from neurologically unimpaired subjects. The most common alteration is hyperphosphorylation of τ, observed in both neurons and glial cells, in certain brain regions, followed by β-amyloid aggregation in the neuropil and vessel walls. Less common protein alterations are those noted for α-synuclein and Tar DNA-binding protein 43. It is noteworthy that these alterations, when found in excess, are diagnostic for various neurodegenerative diseases, such as Alzheimer disease, Pick disease, progressive supranuclear palsy, corticobasal degeneration, Parkinson disease, Lewy body dementia, and frontotemporal lobar degeneration. Since 1990, the neuropathology community has been aware that these protein alterations tend to progress in an orderly neuroanatomically defined manner and have thus designed a method to define a stage or a phase of the protein alteration. The neuropathology community has defined an initiation site, or neuroanatomic area that they presume the alteration originates from, and defined a presumed pattern of progression from the initiation site to other brain areas. Thus a reliable and reproducible description of each case regarding these alterations can be achieved. In addition to the above alterations, the brain tissue is also prone to various vascular alterations that should be registered as seen or not seen even if the significance of these alterations is still unclear.