When Australian actor Chris Hemsworth announced late last year that he would be stepping back from films to concentrate on his health after genetic testing revealed he was at increased risk of Alzheimer’s disease, it sparked an important conversation. It gave pause to many people—especially those with a family history of severe
memory issues, Alzheimer’s disease, or another type of dementia—to consider testing for the same Alzheimer’s gene.
Alzheimer’s disease is a devastating brain disorder. It slowly destroys memory and thinking skills and, over time, the ability to carry out even the most basic tasks. For most people who develop the disease, late-onset symptoms first appear in their mid-60s.
If you are concerned about developing memory issues yourself, here’s what you need to know about genetic testing for Alzheimer’s.
ABOUT THE “ALZHEIMER’S GENE”
The Alzheimer’s gene generally refers to a variant of the apolipoprotein E (Apo E) gene, which is the number-one genetic risk factor for late-onset Alzheimer’s disease. The Apo E gene provides instructions for making apolipoprotein E which serves as a lipid/cholesterol carrier. Lipids are the basic component of cell membranes and play a vital role in healthy brain function. Problems with lipid homeostasis are thought to play a role in Alzheimer’s disease and related disorders,
research in a 2020 issue of
Lipids and Alzheimer’s Disease suggests.
There are three common forms/variants of the Apo E gene: E2, E3, and E4.
- Apo E2 is the least common and has a protective effect against Alzheimer’s.
- Apo E3 is the most common, found in more than half the population. It does not appear to impact the risk of Alzheimer’s.
- Apo E4 is less common than E3, and it markedly increases the risk for late-onset Alzheimer’s disease as research indicates it exacerbates beta-amyloid deposition and plaque formation in the brain.
You, of course, get one Apo E gene from each parent. Combinations of E3 and E2 genes are not concerning. However, if you have one E4 gene, your
risk of Alzheimer’s increases by 2-and-a-half times. If you have two, your risk increases by 5 to 15 times,
research has found. If you develop Alzheimer’s from other causes, having the Apo E4 gene causes symptoms to appear 2 to 5 years earlier than in people who do not have the gene.
HOW PREVALENT IS THE APO E4 GENE?
About 25% of people carry at least one E4 gene, and about 2 to 3% carry two, according to data from the
National Institutes of Health. With just one Apo E4 gene, the odds of developing late-onset Alzheimer’s are 25% in comparison to a 5-10% risk for people who do not have the gene.
While that’s a significant increase, it is important to note that inheriting Alzheimer’s Apo E4 gene does not mean you will absolutely develop the disease; a full 75% of those who test positive never do. In fact, even in cases when a person has one Apo E4 gene and develops dementia, there’s a possibility that the symptoms are something other than Alzheimer’s. However, if there are two Apo E4 genes present in someone exhibiting dementia, Alzheimer’s is very likely the root cause.
WHY TEST FOR THE ALZHEIMER’S GENE?
Some people with familial memory issues know that they are at increased risk for Alzheimer’s and may not see the value of genetic testing. Others simply do not want to know because they feel powerless to do anything about it. Here are some important facts if you are considering testing.
Motivation
If you discover that you are at increased risk of Alzheimer’s disease due to your genes, you will be highly motivated to make a more concerted effort to reduce all the other risk factors with your lifestyle choices.
Epigenetics
Most people overlook the power of epigenetics as it is still an emerging field. While we can’t change what genes we inherit, the field of epigenetics shows us that we have a lot of power to influence them—and this is true for people who test positive for the Apo E4 gene.
Epigenetic means “above or on top of the gene.” It is only in recent decades that scientists have found that your lifestyle habits, emotions, and environment can activate genes or turn them off —making certain diseases more or less likely in you, and in future generations that inherit your genes. In other words, environmental influences—such as the foods you regularly consume (particularly when pregnant),
stress, exposure to toxic chemicals, and so on—influence the genes you pass on to your children, grandchildren, and beyond.
Some
research in
Epigenomics suggests that epigenetics may play a key role in understanding different forms of dementia and other mental health and degenerative disorders. For instance,
research in the
European Journal of Clinical Nutrition suggests that nutrition may be epigenetically influential in the development of forms of dementia like Alzheimer’s.
Empowers You With Information
Knowing you have the Apo E4 gene can help you to make critical decisions about your own health—or possibly your children’s if you choose to get them screened.
For example, having one or two copies of the gene makes it more likely that you will experience vascular problems,
research in
Neurology has indicated.
Studies also show that the Apo E4 gene is associated with lower overall cerebral blood flow. Thus, taking care of your vascular health is critical for your brain if you test positive for the Apo E4 gene!
Additionally, some
research indicates that if you have the Apo E4 gene and undergo
chemotherapy, it increases the risk of Alzheimer’s disease even more, and
studies show a similar increase for those who have the E4 gene and suffer
head injuries. Parents may want to screen their kids who play high-contact sports.
Ongoing research on Apo E4 also reveals
lifestyle actions you can take to reduce your risk of Alzheimer’s as well.
For example, recent
study findings provide preliminary support for testing choline supplementation to help reverse detrimental alterations in the lipid metabolism of brain cells that can occur in those who carry the E4 gene.
An in-depth 2021 nutrition
study found certain diets, foods, and nutrient recommendations for Apo E4 carriers to reduce Alzheimer’s risk (as part of a risk-reducing lifestyle that includes restful
sleep, exercise, low stress, and social connection). Among them, the study recommended
limiting alcohol consumption, choosing a low-glycemic index/low-carbohydrate diet, and including certain beneficial foods such as olive oil, cruciferous vegetables, and fatty fish.
Two earlier
studies conducted by researchers in Finland and Sweden found that exercising at least twice a week in midlife lowers the risk of dementia more than 20 years later – and this protective influence is stronger in people who have the Apo E4 gene.
GETTING SCREENED FOR THE ALZHEIMER’S GENE
Especially for people with a family history of memory problems, dementia, or Alzheimer’s,
early screening (around age 40) with cognitive tests and questionnaires, and possibly the addition of
brain SPECT imaging is important. Any doctor can order an Apo E gene status blood test. That said, genetic testing is not to be taken lightly and should be discussed with your healthcare provider.
A 2018
study in
Genetics in Medicine showed that finding out you have the APOE4 gene can cause psychological distress, including feelings of fear, anxiousness, or anger. If you choose to get tested, be aware that you may have a strong emotional reaction. However, understand that in this same study, participants reported that ultimately, knowing about their increased risk motivated them to make lifestyle changes that had a beneficial impact on their lives in the long term.
Memory problems, dementia, Alzheimer’s disease, and other mental health issues can’t wait. At Amen Clinics, we’re here for you. We offer in-clinic brain scanning and appointments, as well as mental telehealth, clinical evaluations, and therapy for adults, teens, children, and couples. Find out more by speaking to a specialist today at 888-288-9834 or visit our contact page here.
