Alzheimer s Disease And Its Effects - 1831 Words

Alzheimer’s disease is the biggest cause of senile dementia in Europe and the United States affecting nearly 36 million people worldwide (Prince, Albanese, Guerchet Prina, 2014). It is a chronic neurodegenerative disorder of the brain, severely affecting the temporal and frontal lobes, and in particular the limbic structures contained within these regions (Hooper Vogel, 1976). Such structures include the hippocampus (contributing particularly to spatial memory (Schmajuk, 1984) and the amygdalae, both of which are primarily affected (Chan et al, 2001). As such, Alzheimer’s disease (AD) is characterised by a progressive cognitive impairment, usually beginning with memory loss and progressing further to involve multiple cognitive and†¦show more content†¦Nevertheless, both types of AD are recognised pathologically by the build-up of intracellular neurofibrillary tangles, extracellular amyloid plaques, and massive neuronal and synaptic loss (Carmo Cuello, 2013). Neurofibrillary tangles are aggregates of hyper-phosphorylated tau protein and plaques are mostly insoluble deposits of ÃŽ ²-amyloid, resulting from the cutting of the amyloid precursor protein (APP) (Farooqui Farooqui, 2011). The discovery of mutations in the APP gene which cause familial AD lead to the articulation of the amyloid cascade hypothesis (ACH) (Hardy Asllop, 1991). A large amount of evidence supports this view; however a number of findings are contrary to its proposal. As a result, Armstrong (2011) proposed a revision of the hypothesis, postulating that the main trigger for the development of the disease is the ageing of the brain and related wear and tear such as head trauma and stress; collectively referred to as the â€Å"allostatic load† (Carroll, 2002). Furthermore, a greater emphasis has now been placed on the role of small, soluble amyloid oligomers which seem to be the cause of early cell dysfunction in AD, rather than the large, insoluble amyloid fibr ils. (Ferreira, Vieira De Felice, 2007). The development of transgenic animal models of AD has been used to further understand the neural mechanisms associated with the disease, to test therapies and treatments and to