Let's talk about Late-Onset Alzheimer’s Disease & Genetics
Learn more about how a person’s genetics, age, and other factors all may influence the risk of developing late-onset Alzheimer’s disease.
Concerned about how your genetics and lifestyle might be contributing to your risk? Talk to your doctor. Want to learn a little more about late-onset Alzheimer’s disease? Read on.
What is Alzheimer’s disease?
Alzheimer’s disease is a form of dementia. It’s characterized by progressive memory loss, gradual cognitive decline, and personality changes.
In the United States alone, about 10 percent of white Americans, 19 percent of Black Americans, and 14 percent of Latinos who are older than 65 have Alzheimer’s disease, according to the Alzheimer’s Association. There are two different types of Alzheimer’s disease: late-onset Alzheimer’s disease and early-onset Alzheimer’s disease. Both have symptoms that are much the same. The big difference, as the name implies, is that early-onset Alzheimer’s begins at a younger age, before the age of 65. It is also much rarer, and it is considered a distinct form of Alzheimer’s. Late-onset Alzheimer’s disease is the most common form of Alzheimer’s disease.
What are the symptoms of late-onset Alzheimer’s disease?
Alzheimer’s disease is a progressive condition, meaning that it develops over time. The earliest signs may be changes that happen in the brain that do not result in any obvious outward symptoms.
The first outward symptoms typically include such things as memory loss or cognitive difficulties. These are different from normal changes we may all experience during aging in that they disrupt a person’s life.
Examples of some symptoms of Alzheimer’s disease, according to the CDC, might include
- Memory loss that disrupts normal life
- Challenges in planning or solving problems
- Difficulty completing familiar tasks at home, at work, or at leisure
- Confusion with time or place
- Trouble understanding visual images and spatial relations
- New problems with words in speaking or writing
- Misplacing things and losing the ability to retrace steps
- Decreased or poor judgment
- Withdrawal from work or social activities
- Changes in mood and personality
What are the stages of late-onset Alzheimer’s disease?
As late-onset Alzheimer’s disease progresses, the symptoms become more serious.
Early stages of the disease might include difficulty remembering conversations, names, or events. These early symptoms might also include changes in mood, depression, and a lack of interest in life.
As the disease progresses, these symptoms can become more pronounced and may include difficulty recognizing the faces or remembering the names of loved ones. In later stages, as the disease becomes more severe, symptoms may include difficulty in communicating, disorientation, confusion, poor judgment, and behavioral changes.
In the final stages of the condition, at its most severe, symptoms might include difficulty speaking, swallowing, and walking. At these later stages, a person may have difficulty feeding themselves or dressing, and they often require specialized care.
How is Alzheimer’s disease diagnosed?
If you are concerned about symptoms, it’s important to talk to your doctor or healthcare professional. As part of its Healthy Brain Initiative, the CDC emphasizes the importance of early detection, which gives people and their healthcare providers information, care, and support for their diagnosis.
According to the CDC, people are typically not aware that they have the condition until much later. It’s only when symptoms become increasingly disruptive, for instance when someone gets lost in a familiar place, that leads to the condition first getting diagnosed.
A doctor evaluating someone with early signs of Alzheimer’s disease may do cognitive tests and then refer them to a specialist for further testing. Some of those additional tests may include brain imaging and/or lab tests to look for signs of the disease, which can include structural changes in the brain or changes in levels of certain types of proteins.
Is late-onset Alzheimer’s disease genetic?
Late-onset Alzheimer’s disease is influenced by genetics, but genetics is only one component of why some people develop the condition. Researchers believe that a combination of genetic, environmental, and lifestyle factors all play a role.
As for genetics, the ε4 variant in the APOE gene is the most common genetic variant associated with an increased risk of developing late-onset Alzheimer’s disease, but there are other genes and genetic variants that also influence the risk.
The APOE gene is involved in making a protein called apolipoprotein E, which helps control the levels of cholesterol and fats in the blood. It is not known exactly how the ε4 variant increases the risk of late-onset Alzheimer’s disease.
It’s important to note that having the ε4 variant does not mean that you will develop late-onset Alzheimer’s disease. There are other genetic and non-genetic factors that also play a role.
Why should you care about late-onset Alzheimer’s disease?
Alzheimer’s affects an estimated 6.5 million people in the US alone, according to the Alzheimer’s Association. It’s currently the seventh leading cause of death, and by mid-century, the estimates are that more than 12.7 million people in the US will be living with Alzheimer’s disease. Worldwide, Alzheimer’s makes up as much as 70 percent of the more than 55 million people living with dementia, according to the World Health Organization.
Beyond the direct impact on those living with the disease, Alzheimer’s impacts their families and loved ones both emotionally and financially. In 2022, it’s projected that Alzheimer’s and other dementias may cost the nation $321 billion, according to the Alzheimer’s Association.
While there currently is no cure for Alzheimer’s, medication may be used to delay or ease symptoms. There is also evidence that healthy lifestyle changes could help lower the risk of developing late-onset Alzheimer’s. Understanding more about the condition, efforts by researchers to find new ways of treating it, and ways to lessen the risk, could help you or someone you know.
Who is at most risk?
Genetics plays a role, so a person with the ε4 variant in the APOE gene has a higher likelihood of developing late-onset Alzheimer’s, but other non-genetic factors are also associated with higher or lower risk. And many of these factors are interrelated — diet, exercise, and heart health, for instance.
Simply being older than 65 puts one at a higher risk. Between 1-to-4 percent of people have Alzheimer’s at the age of 65, and the percentages increase as people reach their 70s, 80s, 90s, and beyond.
One’s sex may also play a role. More females than males have late-onset Alzheimer’s disease. This may be partly due to the fact that women tend to live longer than men, but biological and lifestyle differences likely also play a role. Also, studies suggest that the APOE ε4 variant is associated with a greater risk for late-onset Alzheimer’s disease in females than in males.
Family Health History
Your family health history also matters. People who have a parent or sibling who has had late-onset Alzheimer’s are more likely to develop the condition. This could be due to shared genetics, but it could also reflect a shared home environment and lifestyle.
Many studies have investigated the relationship between cardiovascular risk factors and Alzheimer’s disease. Evidence suggests that factors that increase the risk of cardiovascular disease (obesity, high cholesterol, and high blood pressure) also increase the risk of Alzheimer’s disease in older age. Having type 2 diabetes and smoking have also both been linked to an increased risk of developing cardiovascular disease and Alzheimer’s disease.
African Americans and Hispanics develop late-onset Alzheimer’s disease at higher rates than people of European and Asian descent. This may be due to differences in rates of other health conditions such as heart disease and diabetes, as well as differences in lifestyle and socioeconomic factors. The frequency of the APOE ε4 variant also differs between these groups.
Learn more about reducing risks associated with developing late-onset Alzheimer’s here.
What can you do?
There is currently no cure for Alzheimer’s disease. Medication may be used to delay or ease symptoms, but there are also lifestyle changes one can take that may help reduce the risk of developing late-onset Alzheimer’s disease.
- Diet — Studies suggest a diet with plenty of green leafy vegetables, fruits, whole grains, and healthy fats such as those found in fish, nuts, and olive oil is associated with a reduced risk of developing Alzheimer’s disease.
- Intellectual Activity — Researchers suggest that exercising the brain through activities like reading, writing, and doing puzzles may help promote brain health.
- Exercise — Evidence suggests that exercise benefits the brain and may decrease the risk of developing Alzheimer’s disease. This may result from many factors, including improvements in blood flow and a lower risk of developing metabolic and cardiovascular diseases.
- Heart Health – There is evidence that reducing hypertension — high blood pressure — reduces the chance for cognitive impairment in older adults. So taking action to control high blood pressure through diet, exercise, and, when appropriate, medication to lower blood pressure, could help lessen the risk for dementia later in life.
Consult with a healthcare professional before making any major lifestyle changes.
Is late-onset Alzheimer’s disease preventable?
There is currently no way to prevent Alzheimer’s disease. However, there is growing evidence that healthy behavior change may help reduce the risk for cognitive decline and possibly dementia. For example, an NIH study showed that lowering systolic blood pressure could help reduce mild cognitive impairment.
If your parents or a sibling had late-onset Alzheimer’s disease, are you more likely to develop it?
If you have a first-degree relative who has had late-onset Alzheimer’s disease, it may mean that you have a higher chance of developing the condition. This might be explained by shared genetics, or it could also be related to sharing a similar lifestyle or family environment.
What can you do if you’ve learned that you are at a higher risk for late-onset Alzheimer’s disease?
Talk to a healthcare professional. Having a higher risk for late-onset Alzheimer’s disease does not mean that you will develop the condition. There are also resources you can seek out for support or to learn more about Alzheimer’s disease.
You can learn more about Alzheimer’s disease from the following resources:
- National Institute on Aging
- Centers for Disease Control and Prevention
If you have questions about your results or how they might affect you or your family, a genetic counselor may be able to help. Learn more about genetic counseling.
You can find out whether you may have an increased risk of developing late-onset Alzheimer’s disease based on your genetics with the 23andMe Late-Onset Alzheimer’s Disease Genetic Health Risk report*. The report looks for the ε4 variant in the APOE gene associated with late-onset Alzheimer’s disease. The report is available through the 23andMe Health + Ancestry Service.
*The 23andMe PGS test uses qualitative genotyping to detect select clinically relevant variants in the genomic DNA of adults from saliva for the purpose of reporting and interpreting genetic health risks. It is not intended to diagnose any disease. Your ethnicity may affect the relevance of each report and how your genetic health risk results are interpreted. Each genetic health risk report describes if a person has variants associated with a higher risk of developing a disease, but does not describe a person’s overall risk of developing the disease. The test is not intended to tell you anything about your current state of health, or to be used to make medical decisions, including whether or not you should take a medication, how much of a medication you should take, or determine any treatment. The Late-Onset Alzheimer’s Disease genetic health risk report is indicated for reporting of the ε4 variant in the APOE gene and describes if a person has a variant associated with an increased risk of developing late-onset Alzheimer’s disease. The ε4 variant included in this report is found and has been studied in many ethnicities. Detailed risk estimates have been studied the most in people of European descent.