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What is Alzheimer's Disease?
Alzheimer's Disease is a form of dementia. It is a progressive disease that affects a person's control of their thought, memory, and language. Alzheimer's begins as minor memory loss and progresses to the point it may affect a person's ability to carry out daily tasks [1]. These symptoms are caused by shrinking of the brain called atrophy and brain cells dying. Complications from the brain loss such as dehydration, malnutrition, or infection can lead to death in the late stages of Alzheimer's. [2]
Alzheimer's Disease is a form of dementia. It is a progressive disease that affects a person's control of their thought, memory, and language. Alzheimer's begins as minor memory loss and progresses to the point it may affect a person's ability to carry out daily tasks [1]. These symptoms are caused by shrinking of the brain called atrophy and brain cells dying. Complications from the brain loss such as dehydration, malnutrition, or infection can lead to death in the late stages of Alzheimer's. [2]
Symptoms and Treatment
One of the most well known symptoms of Alzheimer's is memory loss. This memory loss often affects a person's ability to complete daily activities. Other symptoms include new trouble with spatial relationships and new difficulties with language including reading or writing [3]. Current treatment for Alzheimer's is mostly symptoms management, since there currently is no cure. Some treatments like Lecanemab aim to slow the disease by decreasing the rate of beta plaque formation, but only works in the early stages of Alzheimer's. [4]
One of the most well known symptoms of Alzheimer's is memory loss. This memory loss often affects a person's ability to complete daily activities. Other symptoms include new trouble with spatial relationships and new difficulties with language including reading or writing [3]. Current treatment for Alzheimer's is mostly symptoms management, since there currently is no cure. Some treatments like Lecanemab aim to slow the disease by decreasing the rate of beta plaque formation, but only works in the early stages of Alzheimer's. [4]
APOE is a Protein Coding Gene
The APOE gene codes for the apolipoprotein. Apolipoprotein is a protein involved in lipid transport. APOE mediates the binding of lipoproteins in both plasma and cell surface. There are specific receptors that receive lipoprotein complexes bound with APOE proteins. This specific reception allows APOE to moderate the transport of lipids throughout different cell and tissue types in the body. [6]
The APOE gene codes for the apolipoprotein. Apolipoprotein is a protein involved in lipid transport. APOE mediates the binding of lipoproteins in both plasma and cell surface. There are specific receptors that receive lipoprotein complexes bound with APOE proteins. This specific reception allows APOE to moderate the transport of lipids throughout different cell and tissue types in the body. [6]
APOE e4 Allele and Alzheimer's
The apolipoprotein E4 (APOE e4) allele is the greatest genetic risk factor for Alzheimer's currently known. The allele increases the chance of getting Alzheimer's as well as lowering the average age of onset. The allele is dosage dependent meaning while being heterozygous with the APOe4 allele increases your risk, being homozygous increases your risk in a higher percent. The APOE e4 allele is associated with an increase in amyloid beta plaque accumulated in the brain. APOE e4 is also linked to an increase in tau in the brain. [5]
The apolipoprotein E4 (APOE e4) allele is the greatest genetic risk factor for Alzheimer's currently known. The allele increases the chance of getting Alzheimer's as well as lowering the average age of onset. The allele is dosage dependent meaning while being heterozygous with the APOe4 allele increases your risk, being homozygous increases your risk in a higher percent. The APOE e4 allele is associated with an increase in amyloid beta plaque accumulated in the brain. APOE e4 is also linked to an increase in tau in the brain. [5]
Gap In Knowledge
How does APOE affect lipid transport in the brain
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References
61. “What Is Alzheimer's Disease?” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 26 Oct. 2020, https://www.cdc.gov/aging/aginginfo/alzheimers.htm#:~:text=Alzheimer's%20disease%20is%20the%20most,thought%2C%20memory%2C%20and%20language.
2. Koutsodendris N, Nelson MR, Rao A, Huang Y. Apolipoprotein E and Alzheimer's Disease: Findings, Hypotheses, and Potential Mechanisms. Annu Rev Pathol. 2022 Jan 24;17:73-99. doi: 10.1146/annurev-pathmechdis-030421-112756. Epub 2021 Aug 30. PMID: 34460318
3. “10 Early Signs and Symptoms of Alzheimer's.” Alzheimer's Disease and Dementia, Alzheimer's Association, 2023, https://www.alz.org/alzheimers-dementia/10_signs.
4. Breijyeh Z, Karaman R. Comprehensive Review on Alzheimer's Disease: Causes and Treatment. Molecules. 2020 Dec 8;25(24):5789. doi: 10.3390/molecules25245789. PMID: 33302541; PMCID: PMC7764106.
5. Martens YA, Zhao N, Liu CC, Kanekiyo T, Yang AJ, Goate AM, Holtzman DM, Bu G. ApoE Cascade Hypothesis in the pathogenesis of Alzheimer's disease and related dementias. Neuron. 2022 Apr 20;110(8):1304-1317. doi: 10.1016/j.neuron.2022.03.004. Epub 2022 Mar 16. PMID: 35298921; PMCID: PMC9035117.
6. Huang Y, Mahley RW. Apolipoprotein E: structure and function in lipid metabolism, neurobiology, and Alzheimer's diseases. Neurobiol Dis. 2014 Dec;72 Pt A:3-12. doi: 10.1016/j.nbd.2014.08.025. Epub 2014 Aug 27. PMID: 25173806; PMCID: PMC4253862.