One of the hallmarks of Alzheimer’s disease is the presence of plaque in the brain, which is why researchers have been working diligently to find ways to remove it safely and effectively. It’s a challenge that has come one step closer to being resolved after the findings of a recent study.
Plaque found in the brain of people with Alzheimer’s disease forms when pieces of protein called beta-amyloid accumulate and clump together. A form of protein called apolipoprotein E (ApoE) is produced by the ApoE gene and supports the accumulation of plaque in the brain. More specifically, ApoE transports cholesterol and beta-amyloid to the brain if it is not adequately filtered out or removed.
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Not all ApoE is created equal; that is, the two ApoE genes in the body can produce three different types (alleles): ApoE2, ApoE3, or ApoE4. Therefore, six different combinations are possible. People who have one or two ApoE2 alleles seem to have a reduced risk of developing Alzheimer’s disease, while having the ApoE3 alleles doesn’t seem to have any effect on risk. About 20 percent of people have the ApoE4 alleles, and they are at the greatest risk of developing late-onset Alzheimer’s disease.
ApoE has both positive and negative functions in the body. While it’s not entirely welcome in the brain, it does serve a critical function in the liver, where it filters out cholesterol. Researchers have discovered that the absence of ApoE in some parts of the body is associated with both a rise in blood cholesterol levels and a negative impact on cognitive function.
In this new study, investigators wanted to know whether removing ApoE from the brain would have a detrimental effect on brain function. To find out, they removed nearly all of the ApoE from the brains of mice while not touching the protein’s presence in the liver, which filters cholesterol. The result, the mice were able to maintain their memory and learning abilities.
However, when the researchers removed ApoE from both the brain and the liver, the mice lost their cognitive function and had elevated cholesterol levels. Therefore, the authors of the study concluded that reducing the amount of ApoE in the brain could one day be a viable treatment approach for treating people with Alzheimer’s disease. The findings are now the basis of ongoing research at several centers to further explore the effects and consequences of removing ApoE4 from the brain.
Image via A Health Blog
Sources
Carman A. What ApoE means for your health. Cognitive Vitality
Lane-Donovan C et al. Genetic restoration of plasma ApoE improves cognition and partially restores synaptic defects in ApoE-deficient mice. Journal of Neuroscience 2016 Sept 28 online
