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group_4_presentation_2_-_alzheimers [2017/03/10 14:29] josephht |
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| - **Changes in mood and personality**: I.e. becoming confused, depressed and anxious | - **Changes in mood and personality**: I.e. becoming confused, depressed and anxious | ||
| - | <box 80% round | > {{:ad.png|}} </box| Figure 2 - Common symptoms of Alzheimer’s. (Cephalicvein, 2016)> | + | <box 90% round | > {{:ad.png|}} </box| Figure 2 - Common symptoms of Alzheimer’s. (Cephalicvein, 2016)> |
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| * Alzheimer’s is least prevalent in Sub-Saharan Africa. | * Alzheimer’s is least prevalent in Sub-Saharan Africa. | ||
| * Alzheimer’s and other dementias are the top cause for disabilities in later life. (Alzheimer’s Disease International, 2015) | * Alzheimer’s and other dementias are the top cause for disabilities in later life. (Alzheimer’s Disease International, 2015) | ||
| - | <box 90% round | > {{:epia.png|}} </box| Figure 3 - Projected growth of Dementia in the world in several areas. (Alzheimer's Disease International, 2015) > | + | <box 70% round | > {{:epia.png|}} </box| Figure 3 - Projected growth of Dementia in the world in several areas. (Alzheimer's Disease International, 2015) > |
| The incidence of AD is approximately 5–8 for per thousand person, which represents half of new dementia cases each year are AD (Bermejo-Pareja et al, 2008). One of the primary risk factor for AD, where there is a correlation of the incidence rate of every five years after the age of 65, the risk of acquiring AD approximately doubles (Di Carlo et al, 2002). Furthermore, there is also higher incidence rates in women compared to men of developing AD particularly in the population older than 85 (Andersen et al, 1999). | The incidence of AD is approximately 5–8 for per thousand person, which represents half of new dementia cases each year are AD (Bermejo-Pareja et al, 2008). One of the primary risk factor for AD, where there is a correlation of the incidence rate of every five years after the age of 65, the risk of acquiring AD approximately doubles (Di Carlo et al, 2002). Furthermore, there is also higher incidence rates in women compared to men of developing AD particularly in the population older than 85 (Andersen et al, 1999). | ||
| In the United States, Alzheimer prevalence was estimated to be 1.6% in 2000 both overall and in the 65–74 age group, with the rate increasing to 19% in the 75–84 group and to 42% in the greater than 84 group. (Hebert et al, 2003) Prevalence rates of AD is less in developed countries compared to developing countries (Ferri et al, 2006). AD accounts to 50-70% of all forms of dementia, making it the leading cause of this neurodegenerative disease (7). Furthermore, due to the rapid increase of dementia, individuals would also be at increased risk of AD. Another study estimated that in 2006, 0.40% of the world population were afflicted by AD, and that the prevalence rate would triple and the absolute number would quadruple by 2050. (Brookmeyer et al, 2007) | In the United States, Alzheimer prevalence was estimated to be 1.6% in 2000 both overall and in the 65–74 age group, with the rate increasing to 19% in the 75–84 group and to 42% in the greater than 84 group. (Hebert et al, 2003) Prevalence rates of AD is less in developed countries compared to developing countries (Ferri et al, 2006). AD accounts to 50-70% of all forms of dementia, making it the leading cause of this neurodegenerative disease (7). Furthermore, due to the rapid increase of dementia, individuals would also be at increased risk of AD. Another study estimated that in 2006, 0.40% of the world population were afflicted by AD, and that the prevalence rate would triple and the absolute number would quadruple by 2050. (Brookmeyer et al, 2007) | ||
| - | <box 90% round | > {{:deathsa.png|}} </box| Figure 4 - Deaths due to Alzheimer's in 2012 (Red indicating larger number of deaths compared to orange). (Wikipedia, 2013) > | + | <box 70% round | > {{:deathsa.png|}} </box| Figure 4 - Deaths due to Alzheimer's in 2012 (Red indicating larger number of deaths compared to orange). (Wikipedia, 2013) > |
| - | <box 90% round | > {{:resized.png|}} </box| Figure 5 - The prevalence and incidence rates in various areas compared to an age category. (Qiu, Kivipelto & Strauss, 2009) > | + | <box 70% round | > {{:resized.png|}} </box| Figure 5 - The prevalence and incidence rates in various areas compared to an age category. (Qiu, Kivipelto & Strauss, 2009) > |
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| The early onset of Alzheimer’s disease (AD) is marked by neuronal loss occurring within the entorhinal cortex of the brain, which is located under the cerebral cortex (Columbia University Medical Center, 2013). The major function of this region of the brain is to submit information to and from structures in the hippocampus. The hippocampus then accumulates this information and stores it as long-term memory. Any pathology in these areas of the brain would affect an individual’s memory, being as they are so closely associated with memory processing (Saylor, 2017). Additionally, pathology is also seen in the amygdala, a region accountable for emotional responses and behaviour to various stimuli (Saylor, 2017). During the moderate onset of AD, cortical and hippocampal atrophy continues, alongside the widening of cerebrospinal fluid-filled ventricles within the brain (Salcudean, 2010). This ventricle widening causes further damage to surrounding tissues in the brain. A patient affected by AD may experience an inability to accomplish daily tasks, increased anxiety and emotional outbursts, and language impairment among several other symptoms as their memory loss continues. The severe (late) stage of dementia is characterized by the presence of two major neuropathological trademarks including intracellular neurofibrillary tangles and extracellular amyloid plaques (Salcudean, 2010). At this point, irreversible neuronal loss is evident throughout the brain, causing extensive dysfunction and extreme atrophies to affected areas (see Figure 6). This individual would experience severe loss of autonomic functions and would require complete dependence on others for care. | The early onset of Alzheimer’s disease (AD) is marked by neuronal loss occurring within the entorhinal cortex of the brain, which is located under the cerebral cortex (Columbia University Medical Center, 2013). The major function of this region of the brain is to submit information to and from structures in the hippocampus. The hippocampus then accumulates this information and stores it as long-term memory. Any pathology in these areas of the brain would affect an individual’s memory, being as they are so closely associated with memory processing (Saylor, 2017). Additionally, pathology is also seen in the amygdala, a region accountable for emotional responses and behaviour to various stimuli (Saylor, 2017). During the moderate onset of AD, cortical and hippocampal atrophy continues, alongside the widening of cerebrospinal fluid-filled ventricles within the brain (Salcudean, 2010). This ventricle widening causes further damage to surrounding tissues in the brain. A patient affected by AD may experience an inability to accomplish daily tasks, increased anxiety and emotional outbursts, and language impairment among several other symptoms as their memory loss continues. The severe (late) stage of dementia is characterized by the presence of two major neuropathological trademarks including intracellular neurofibrillary tangles and extracellular amyloid plaques (Salcudean, 2010). At this point, irreversible neuronal loss is evident throughout the brain, causing extensive dysfunction and extreme atrophies to affected areas (see Figure 6). This individual would experience severe loss of autonomic functions and would require complete dependence on others for care. | ||
| - | <box 50% round | >{{:brain-w550.jpg|}} </box|Figure 6: Normal brain vs. Brain affected with Alzheimer's Disease. Atrophy of cerebral cortex, and hippocampus is shown, as well as enlarged ventricles (Whole Health Insider, 2013)> | + | <box 45% round | >{{:brain-w550.jpg|}} </box|Figure 6: Normal brain vs. Brain affected with Alzheimer's Disease. Atrophy of cerebral cortex, and hippocampus is shown, as well as enlarged ventricles (Whole Health Insider, 2013)> |
| Amyloid precursor proteins (APP) are constantly released during normal metabolism in the brain. Little is understood about the functioning of these proteins, especially regarding its part in the pathogenesis of AD (Lin, 2001). APP can be cleaved by α-secretase proteases, which would result in normal functioning of the brain, and no buildup of extracellular amyloid plaque (Lichtenthaler, 2012) (See left hand side of Figure 7). However, if the APP molecule is cleaved by β-secretase and/or γ-secretase, amyloid-β peptide fragments are released into the extracellular space due to an abnormal cleavage of the protein by these enzymes (Salcudean, 2010). In small amounts, this procedure is not harmful and may even be desirable for normal synaptic functioning. More often than not, however, the over activity of these β- and γ-secretase enzymes cause a large, toxic amount of amyloid-β peptide fragments. In excessive amounts, these fragments aggregate and form plaque in the extracellular space (see right hand side of Figure 7). PSEN1 and PSEN2 (Presenilin 1 and 2 respectively) play a part in regulating APP processing through γ-secretase, but mutuations in these protein molecules increase γ-secretase activity, which can lead to even more plaque formation (Salcudean, 2010). A huge component of these plaques are found throughout the brains of patients affected by AD, showing that they may play a huge role in the loss of functioning of the brain in these individuals (Lin, 2001). | Amyloid precursor proteins (APP) are constantly released during normal metabolism in the brain. Little is understood about the functioning of these proteins, especially regarding its part in the pathogenesis of AD (Lin, 2001). APP can be cleaved by α-secretase proteases, which would result in normal functioning of the brain, and no buildup of extracellular amyloid plaque (Lichtenthaler, 2012) (See left hand side of Figure 7). However, if the APP molecule is cleaved by β-secretase and/or γ-secretase, amyloid-β peptide fragments are released into the extracellular space due to an abnormal cleavage of the protein by these enzymes (Salcudean, 2010). In small amounts, this procedure is not harmful and may even be desirable for normal synaptic functioning. More often than not, however, the over activity of these β- and γ-secretase enzymes cause a large, toxic amount of amyloid-β peptide fragments. In excessive amounts, these fragments aggregate and form plaque in the extracellular space (see right hand side of Figure 7). PSEN1 and PSEN2 (Presenilin 1 and 2 respectively) play a part in regulating APP processing through γ-secretase, but mutuations in these protein molecules increase γ-secretase activity, which can lead to even more plaque formation (Salcudean, 2010). A huge component of these plaques are found throughout the brains of patients affected by AD, showing that they may play a huge role in the loss of functioning of the brain in these individuals (Lin, 2001). | ||
| - | <box 50% round | > {{:screen_shot_2017-03-04_at_8.35.30_pm.png|}} </box| Figure 7: Normal cleavage vs Abnormal cleavage of the APP molecule by proteases (da Silva, 2015).> | + | <box 45% round | > {{:screen_shot_2017-03-04_at_8.35.30_pm.png|}} </box| Figure 7: Normal cleavage vs Abnormal cleavage of the APP molecule by proteases (da Silva, 2015).> |
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| - | <box 60% round | > {{:screen_shot_2017-03-04_at_9.05.44_pm.png|}} </box| Figure 8: Healthy vs. Diseased neuron and formation of intracellular neurofibrillary tangles (Brunden, 2008).> | + | <box 45% round | > {{:screen_shot_2017-03-04_at_9.05.44_pm.png|}} </box| Figure 8: Healthy vs. Diseased neuron and formation of intracellular neurofibrillary tangles (Brunden, 2008).> |
