Delivered August 12, 2020. Contributor: Methody G.
To provide an overview of the role of APOe4 in Alzheimer's and provide ways that can potentially reduce the risk of developing the disease.
ApoE4's relevance in Alzheimer's disease
The apolipoprotein E (ApoE) is a protein that helps transport cholesterol throughout the body. There are three types of the ApoE protein: ApoE2, ApoE3, and ApoE4.
The ApoE4 protein increases the aggregation rate of tau proteins in the brain, which, in turn, causes the formation of amyloid-β deposits, the primary cause of Alzheimer's.
The tau protein maintains the structure of neurons. However, when the protein starts to aggregate, the neuron's function slowly declines, leading to the most common forms of neuronal degeneration seen in Alzhemier's disease and other neurodegenerative diseases.
According to several studies, having one copy of the ApoE4 gene increases the chance of succumbing to Alzheimer's by 300% while having two copies of the gene increase the chance by 12 times.
Several studies involving mice have shown that the presence of the ApoE4 gene causes significant damage to the hippocampal region of the brain, causing the mice to lose their memories and eventually die.
On the other hand, mice with the ApoE2 and 3 variations of the ApoE protein showed almost no neural degeneration, with the ApoE2even showing some promise in protecting against the development of Alzheimer's.
The ApoE4 was also found to induce inflammation in the brain, activating a type of immune cells called microglia. The phenomenon caused a much higher rate of neuronal death in mice with ApoE4 compared to species that could not produce the ApoE protein.
ApoE4 is also responsible for elevating the levels of cholesterol in the brain, which has been theorized to be another trigger for Alzheimer's.
It has been observed that, throughout the human evolution, the change from the ApoE3 to the ApoE4 protein was observed when humans switched from a primarily plant-based diet to a primarily meat-based diet.
As meat-based diets have higher cholesterol levels, they are associated with the resurgence of the ApoE4 protein and the Alzheimer's disease.
To combat that, several scientists have come up with specific diets that can help with managing the bad cholesterol and decrease the neuronal degeneration.
For instance, diets rich in vitamin E slow cognitive decline by reducing the accumulation of beta-amyloid proteins and eliminating free radicals from the brain.
Omega-3 fatty acids have also been found to reduce the risk of Alzheimer's as they are present in bran cell membranes and have a role in transmitting signals between cells.
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