Alzheimer 's Disease ( Ad ) Essay

1098 Words Jul 1st, 2015 5 Pages
Being the most frequent cause of dementia, Alzheimer’s disease (AD) is estimated to cost $172 billion per year in healthcare [1]. While rising at a rate of 4.6 million new cases each year, dementia affected 24.2 million people by 2005, with approximately 70% of these cases attributed to AD [2]. The incidence and prevalence of AD increases exponentially with age, which is more pronounced in the 7th and 8th decades of life. Key pathological hallmarks of AD which are observed in AD brain tissue include extracellular deposition of amyloid-beta (Aβ) in diffuse and neuritic plaques, and intracellular accumulation of hyperphosphorylated tau (p-tau) protein to form neurofibrillary tangles (NFTs) [3]. In addition, both reactive microgliosis, and widespread loss of neurons, white matter, and synapses occur. However the mechanisms behind these pathological changes are still unclear. As a result several hypotheses emerge to describe the causes behind AD.
2. Amyloid hypothesis: In assuming that the accumulation, oligomerization, and aggregation of Aβ in the brain lead to extracellular plaques, which is the primary cause of AD, the amyloid hypothesis emerges. Subsequently, the belief continues that this accumulation leads to the hyperphosphorylation of tau, a precursor to neurofibrillary tangles and neurodegeneration. The foundation of the hypothesis stems from the existence of rare autosomal dominant, early-onset forms of AD (FAD) [4]. Since these mutations affect APP (type I membrane…

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