Normal and pathological brain aging A physiopathological continuum or an involutive duality
For years, there is a controversy whether there is a two-way (involutive duality) of senile involution of the brain, which may be called, respectively, pathway to the physiological or " normal" senility, without signs of dementia but with neuronal adaptative responses, and pathway to "pathological " senility or Alzheimer's Disease (AD), which is characterized by the appearance of a progressive dementia, or, conversely, a single way (continuum) leading from the first morphological or functional signs of senile involution until the final stage of AD dementia in all individuals. Moreover, in recent years, a thorough review of the concepts of the pathological senility / EA is producing, so that is not now considered necessary to have dementia to diagnose a pathological aging process because it is considered that the pathological aging / EA is started at the time that a disturbance in cognitive brain circuits and / or neuropathological changes occurs. With these new criteria different clinic-pathological stages are supposed from normal senility to terminal pathological senility / EA, without dementia (prodromal or asymptomatic) and with varying degrees of dementia. In this review the reasons given in defense of one or another theory are analyzed, as well as the morphofunctional features of normal and pathological senile brains. Most studies indicate that there are very marked differential characteristics between normal brains without dementia and senile pathological brains with dementia, but in other, large discrepancies exist between the presence or absence of dementia and the existence or not of neuropathological signs. The existence or not of the continuum also has a very important practical implication for both prevention and care of the elderly, because the possible number of individuals affected the entire population or only at-risk individuals in the pathological brain senility pathway. There are some areas where research could improve our knowledge on brain aging, especially in the detailed study of healthy control subjects between 30 and 60, "centenarians" with and without dementia and individuals with neuropsychological characteristics different to AD (possible intermediate stages of AD according to the new " lexicon "). It would also be of great interest a comparative study of human brain aging with that of other mammalian species that showed no amyloid or tau pathology and primates that may have amyloid pathology. Transgenic animals with induced amyloid and /or tau pathology, are also important sources of information on pathological aging.
| Main Authors: | , , |
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| Format: | journal article biblioteca |
| Language: | eng |
| Published: |
2014
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| Online Access: | http://hdl.handle.net/20.500.12792/4487 |
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