Alzheimer’s Disease and the APOE Gene


More than 6 million people are living with Alzheimer’s disease, and nearly one in three senior adults die with Alzheimer’s disease or another form of dementia. [1] The effects of this disease are devastating, and have a long-lasting, detrimental effect on people and families across the United States.

Though Alzheimer’s disease is debilitating, researchers are beginning to discover answers in our genes about what causes Alzheimer’s disease. While we haven’t found all the answers – or a cure to prevent it – we do know that genes like APOE can make an impact on your risk for developing this disease during your lifetime.

Let’s dive in and discover how your genes could influence your risk for Alzheimer’s disease, and why testing matters for you.

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What is Alzheimer’s Disease?

Alzheimer’s disease is a progressive, degenerative brain disorder that’s most common among people aged 65 and older, and eventually progresses to dementia and death. Early symptoms of Alzheimer’s disease include:

  • Memory loss
  • Poor judgement
  • Lack of initiative
  • Repeating questions
  • Forgetting conversations
  • Getting lost or wandering
  • Misplacing objects
  • Forgetting words or names

Alzheimer’s disease diagnoses have been steadily increasing, and the numbers are expected to increase to 12.7 million cases by 2050. [1] With such a dramatic increase, you may wonder: what’s behind it all? And is there anything we can do to stop the rise?

What is APOE?

While we don’t know exactly what causes Alzheimer’s disease, we do know that certain genetic factors like the APOE gene have been associated with a greater risk for developing Alzheimer’s disease later in life.

APOE is a gene that helps you make apolipoprotein E, which helps your body move and store cholesterol and fats. Three common forms of the APOE gene include:

  • APOE e2
  • APOE e3
  • APOE e4

While everyone has some form of the APOE gene, the APOE e4 gene can affect your risk of developing Alzheimer’s disease.

In a 1997 meta-analysis, researchers found that the risk of Alzheimer’s disease was significantly increased in individuals who had at least one copy of the APOE e4 genotype. [2] The NIH estimates that about 25 percent of people carry at least one copy of APOE e4, and 2-3 percent of people carry two copies of this gene. [3]

However, research has found that some forms of APOE may actually have the opposite effect. One review found that the APOE e2 variant may actually help prevent Alzheimer’s disease, though how it does this still remains unknown. [4]

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Should I get an APOE test?

There’s nothing you can do to change your genes once you have them – so why is APOE testing important?

It’s important to note that having a certain APOE gene variant doesn’t mean that you’ll definitely develop Alzheimer’s disease. But knowing your gene status can help you take steps to lower your risk.

One 2001 study of 985 people found that people with the APOE e4 gene who were also managing hypertension (or high blood pressure) with high blood pressure medication were at a lower risk for developing dementia and Alzheimer’s disease than those who weren’t taking medication. [5] A similar 2013 study of 118 adults found that managing hypertension may be a potential way to prevent or delay the brain changes that happen as people age.

Another 2013 article found that having type 2 diabetes corresponded with a 60 percent increase in the risk of developing Alzheimer’s disease. [6] Research has also explored the use of choline supplements to slow cognitive decline, and one study performed on mice found that choline supplementation helped reduce Alzheimer’s-like symptoms in those mice. [7] However, no similar study has been conducted on people yet – but we’ll keep you posted on any further emerging research.

While you can’t control what genes life hands you, you do have the power to know what you’ve got so you can take action. Order your at-home APOE test, and get the genetic answers you need to move forward and pursue choices to help you become a healthier you.




Sources

[1] “Facts and Figures.” Alzheimer's Disease and Dementia, Alzheimer's Association, 2021, www.alz.org/alzheimers-dementia/facts-figures.
[2] Farrer, L. A. “Effects of Age, Sex, and Ethnicity on the Association between Apolipoprotein E Genotype and Alzheimer Disease. A Meta-Analysis. APOE and Alzheimer Disease Meta Analysis Consortium.” JAMA: The Journal of the American Medical Association, vol. 278, no. 16, 22 Oct. 1997, pp. 1349–1356., doi:10.1001/jama.278.16.1349.
[3] Sienski, Grzegorz, et al. “APOE4 Disrupts Intracellular Lipid Homeostasis in Human IPSC-Derived Glia.” Science Translational Medicine, vol. 13, no. 583, 3 Mar. 2021, doi:10.1126/scitranslmed.aaz4564.
[4]Li, Zonghua, et al. “APOE2: Protective Mechanism and Therapeutic Implications for Alzheimer’s Disease.” Molecular Neurodegeneration, vol. 15, no. 1, 4 Nov. 2020, doi:10.1186/s13024-020-00413-4.
[5] Guo, Zhenchao, et al. “Apolipoprotein e Genotypes and the Incidence of Alzheimer's Disease among Persons Aged 75 Years and Older: Variation by Use of Antihypertensive Medication?” American Journal of Epidemiology, vol. 153, no. 3, 1 Feb. 2001, pp. 225–231., doi:10.1093/aje/153.3.225.
[6] Vagelatos, N. T., and G. D. Eslick. “Type 2 Diabetes as a Risk Factor for Alzheimer's Disease: The Confounders, Interactions, and Neuropathology Associated with This Relationship.” Epidemiologic Reviews, vol. 35, no. 1, 11 Jan. 2013, pp. 152–160., doi:10.1093/epirev/mxs012.
[7] Velazquez, Ramon, et al. “Lifelong Choline Supplementation Ameliorates Alzheimer’s Disease Pathology and Associated Cognitive Deficits by Attenuating Microglia Activation.” Aging Cell, vol. 18, no. 6, Dec. 2019, doi:10.1111/acel.13037.