Alzheimer's disease, a condition affecting memory and cognitive function, is a great concern for millions of people worldwide. But did you know that there's a genetic factor, the APOE-ε4 allele, which is associated with an increased risk of Alzheimer's, that also has surprising effects on fertility in women?
An interesting study published in the Public Library of Science (PLOS) shared that this unexpected link between APOE-ε4 and fertility may have roots in our evolutionary history. Before the advent of modern medicine, having more children and a longer reproductive period could have provided a survival advantage for our ancestors. So, this gene variant may have persisted in our population because it contributed to the survival of our species. Additionally, this gene probably thrived in environments that were highly exposed to pathogens. In these environments, reproduction was favoured and the expected age was so low that the symptoms of diseases like Alzheimer’s could not be detected.
Understanding APOE-ε4
To understand this strange link further, the team of OnlyMyHealth spoke to Dr Pavan Pai, Consultant Interventional Neurologist, Wockhardt Hospitals, Mira Road. The PLOS study showed that people who inherit one or two copies of the APOE-ε4 allele from their parents have a higher risk of developing Alzheimer's disease. Now for those who are not aware of what a gene is, genes are made up of DNA, which carries genetic information for the development and functioning of an organism.
Also Read: 7 Alzheimer’s Disease Facts To Be Aware Of On World Alzheimer’s Day 2023
The APOE gene aids in making a protein that helps carry cholesterol and other types of fat in the bloodstream. Scientists believe that when there is a problem in this process, it contributes to the development of Alzheimer’s. Commenting on the same, Dr Pai said, “On one side, it increases the risk of Alzheimer's disease later in life. This is a well-known negative aspect. On the other side, it appears to have a positive effect on some women by potentially increasing their fertility. This means that women with this gene variant might find it a bit easier to have children compared to those without it.”
As per the PLOS study, about 15% to 25% of people have this allele, and 2% to 5% carry two copies, which means that this gene was passed on by both parents to their children.
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How Does APOE-ε4 Affect Fertility?
Calling APOE-ε4 a double-edged sword, Dr Pai continued, “It's important to note that scientific research is ongoing in this area, and more studies are needed to fully understand this connection between the APOE-ε4 gene and fertility. But in simple terms, having this gene might have both advantages and disadvantages for certain individuals.” Breaking down the science behind this surprising twist, he explained:
- Enhanced Fertility: Studies have shown that women with one copy of the APOE-ε4 allele tend to have more children than women without it. This means that the gene variant seems to enhance fertility in women.
- Longer Reproductive Years: It's not just about having more children; women with APOE-ε4 may also experience a longer window of time during which they can have children. This is because they tend to reach menopause later than women without the APOE gene variant.
- The Brain-Fertility Trade-Off: Now, you might be wondering how a gene connected to Alzheimer's could also be linked to enhanced fertility. Researchers believe that there might be a trade-off between the brain and fertility. In simple terms, the same genetic variant that affects our brain health may also have positive effects on our ability to have children.
The connection between the APOE-ε4 gene, Alzheimer's disease, and fertility is a fascinating example of how genetics can influence various aspects of our lives. Remember that genetics is incredibly complex, and having the APOE-ε4 allele doesn't guarantee that you'll develop Alzheimer's or experience enhanced fertility. It's just one piece of the puzzle in our genetic makeup. This information about the APOE-ε4 is in no way an attempt to rain on your happy news and damper your spirits about your successful pregnancy. It is simply a nudge that better awareness of risk factors, especially of diseases that are as terrifying as Alzheimer’s, may allow you to seek a timely diagnosis. Since Alzheimer's has no known cause or cure, early detection is your only straw of hope in an ocean of obliviousness caused by Alzheimer-related dementia.