Aging and neurogenesis, a lesion from Alzheimer's disease.

The evidence that neurogenesis occurs in the adult brain and neural stem cells (NSCs) reside in the adult central nervous system (CNS) of mammals opens new avenues and opportunities for our understanding of development and for therapy. Newly generated neuronal cells of the adult brain would contribute to the physio-pathology of the nervous system and the adult brain may be amenable to repair. The contribution of adult neurogenesis to the functioning of the nervous system remains to be elucidated and adult NSCs have yet to be brought to therapy. It is generally accepted that NSCs in the adult brain have a regenerative capacity. Yet, evidences suggest that they may also contribute to pathological developments in neurological diseases. Alzheimer's disease (AD) is a neurodegenerative disease and the hippocampus is one of the regions of the brain the most affected by the disease. AD is characterized by neurodegeneration, amyloid plaques, neurofibrillary tangles, aneuploidy and enhanced neurogenesis in the adult brain. The process of adult neurogenesis holds the potential to generate populations of cells that are aneuploid, particularly in the neurogenic regions. Aneuploid newly generated neuronal cells of the adult brain would contribute to the pathology of AD. Adult neurogenesis would not only contribute to regenerative attempts in the CNS, but also to the pathogenesis of neurological diseases and disorders.