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Is Alzheimer's Hereditary?
Updated on January 31, 2024
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Is Alzheimer's Hereditary?
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Alzheimer’s disease is not necessarily hereditary. However, having a close family member with Alzheimer’s can increase your risk.1  

The National Institutes of Health says that there remains to be no exact single genetic cause of the disease. Instead, it is a combination of environmental, genetic predisposition, and lifestyle factors.

You have a higher risk if you have more than one first-degree relative with Alzheimer’s. Genetics may play a role in familial conditions, although other risk factors are involved.

Is Alzheimer's Hereditary? 2

Alzheimer’s is a progressive condition that affects your brain functions, like memory. It usually appears in people over 65 years old, but other forms of Alzheimer’s may show at an earlier age.

Dementia or gradual memory loss is the most common sign of Alzheimer’s. It usually starts with forgetting small things, often attributed to poor memory. But it does worsen and deteriorate over time, often getting in the way of your day-to-day.2 

Some people with Alzheimer’s disease eventually end up not being able to carry out simple tasks or even conversations.

Can You Inherit Alzheimer’s Disease?

Yes. You may inherit Alzheimer’s disease.

Alzheimer’s has two forms—early-onset and late-onset Alzheimer’s disease. Both have genetic factors.3 

The understanding of Alzheimer’s has now evolved from about ten gene regions that are implicated as a cause. There are now about 70 regions of the gene seen to contribute to Alzheimer’s.

Early-onset Alzheimer’s disease

Early-onset Alzheimer’s disease is also known as younger-onset Alzheimer’s. It usually occurs between the ages of 30 to 60. 

The diagnosis of dementia in this age group is difficult to ascertain. Some diseases can cause memory loss and should be first excluded before diagnosing a person as having early-onset Alzheimer’s disease.

Only a few people have this form of Alzheimer’s. The Alzheimer’s Association estimates that about 5% of Americans with Alzheimer’s have the younger-onset type.4

Studies have strongly linked it to genetic risk. Research shows you can inherit familial Alzheimer’s disease in an autosomal dominant pattern.5

It means you have a 50% chance of inheriting the disorder when one of your parents carries the mutated gene. 

Late-onset Alzheimer’s disease

On the other hand, late-onset Alzheimer’s is the most common. 

There’s no known single gene mutation that certainly causes late-onset Alzheimer’s. Scientists believe it occurs due to several genes.6

Here’s a quick comparison of late-onset and early-onset Alzheimer’s.

Late-onset Alzheimer’sEarly-onset Alzheimer’s
Signs appear in people 65 and onwardsSigns appear in people ages 30 to mid-60s
Most common formRare
No specific genetic mutation, but inheritance may involve a gene called APOE ɛ4Usually caused by gene mutations inherited from parents

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How Genetics Plays a Part in Alzheimer’s Disease

Genetics play a role in determining your traits. For instance, your genes can influence the color of your hair and eyes.

You receive your genes from your parents. If one of them carries a mutated gene, you may have a higher chance of developing a disorder from the genetic mutation.

Some genes can make you more likely to develop Alzheimer’s disease. Research has discovered different genes linked with Alzheimer’s. They fall under two categories:

1. Risk gene

Risk genes cause an increased risk of developing Alzheimer’s. The best-known example is the APOE gene. 40-50 percent of patients who have the gene have Alzheimer’s.

APOE gene contains the instructions to produce apolipoprotein E, the protein that helps carry fats like cholesterol into the bloodstream. 

Studies show that APOE-e4 is a significant risk factor for cerebral amyloid angiopathy (CAA). CAA is a condition where proteins called amyloid accumulate in the walls of the brain arteries.7

Scientists believe one of the primary causes of Alzheimer’s is the protein buildup in the brain. The buildup includes amyloid plaques.7

2. Deterministic gene

Deterministic genes directly cause Alzheimer’s. If you inherit them, you’re guaranteed to develop the genetic condition they carry. However, these genes rarely occur.

Scientists say these genes account for only 1% of Alzheimer’s cases or less.1

The genes that are deterministic to Alzheimer’s disease are amyloid β-protein precursor on chromosome 21, presenilin 1 on chromosome 14, and presenilin 2 on chromosome 1.  But, healthcare experts don’t proactively recommend routine genetic testing.

However, Alzheimer’s disease researchers may sometimes include testing in their studies.

Causes of Alzheimer’s Disease

Scientific experts agree that Alzheimer’s may be a combination of multiple factors affecting the brain cells.

At least, this is what happens in the vast majority of Alzheimer’s cases. Factors involved are aging, genetics, health and lifestyle, and environment.

Aging

As we age, our brain’s stem cells are exposed to different types of stress and damage. Brain stem cells are capable of self-regenerating and forming new nerve cells. Overtime, this function however declines. Nerve cells or neurons transmit information throughout your body. 

But the decline in stem cell regeneration is more rapid in people with Alzheimer’s.

Alzheimer's isn’t a normal part of aging. Studies on how age-related brain changes may contribute to Alzheimer’s are ongoing.

The following changes may harm the neuron and brain cells and cause brain damage:

  • Atrophy or shrinking of some parts of the brain
  • Inflammation
  • Vascular (blood vessels) damage
  • Free radicals or unstable molecules
  • Energy production breakdown within each cells

Genetics

A family history of Alzheimer’s doesn’t necessarily mean you’ll inherit the condition. But it does mean you have a higher chance of developing it.

Both forms of Alzheimer's have genetic factors.

Health and Lifestyle Factors

Research shows your lifestyle and health problems can also contribute to developing Alzheimer’s, including:8

  • Smoking
  • Obesity
  • Diabetes
  • High blood pressure
  • High cholesterol

Scientific experts suspect a cause-and-effect link between heart disease and Alzheimer’s.9 

The connection between heart disease and Alzheimer’s is explained by inflammatory damage to the blood vessels. Vascular damage caused by buildup of plaque or free radicals in the arterial walls can decrease blood flow to the brain. Over time, the slow blood flow can affect and damage your brain cells.

Environmental factors 

Scientists include environmental factors like exposure to air pollution and poor living conditions in Alzheimer’s disease risk.10 

High exposure to air pollution contributes to the development of Alzheimer's. It's especially true for people that are predisposed to it.11

Studies show that exposure to air pollution also slows down stem cell replication. It also increases the production of amyloid beta protein.11

Amyloid beta protein often makes up the protein plaques in the brain of a person with Alzheimer’s.

Can You Prevent Alzheimer’s Completely? 

Alzheimer’s has no exact cause but only several risk factors. As such, there’s no specific way to prevent it. 

But, some evidence shows that diagnosis at a younger age can help with better treatment options. 

Health experts recommend a few things to keep your brain healthy. Taking care of your brain health can also potentially lower your risk of Alzheimer’s. 

Stress reduction and a healthy lifestyle are important steps to keeping your brain healthy. Both of these reduce the overall inflammation in the body, which can cause early neuronal degeneration.

Exercise 

Physical activity can help reduce the likelihood of dementia. Exercise promotes good blood flow and increases the blood flow through your brain.

Exercise can also stimulate the production of chemicals protecting the brain. Regularly exercising for 30 to 60 minutes a week may:11

  • Help sharpen your thinking, reasoning, and learning skills
  • Help improve your memory
  • Increase the size of your hippocampus—the part of the brain linked with memory formation

Healthy diet

Switching to a heart-healthy diet also benefits and protects your brain. Some health experts recommend the DASH (Dietary Approaches to Stop Hypertension) and Mediterranean diets.12 

Both diets limit your intake of sugar and saturated fats. They also emphasize choosing vegetables, fruits, and fat-free foods for your meals.

Socialize

Experts recommend maintaining strong social connections to be mentally active. Some studies find that socializing reduces your risk of developing Alzheimer’s.13

Socialization plays a role in preventing cognitive decline, whether you’re connecting with others or with nature.

Social activities, like family interactions and social clubs, support brain health. They help slow down cognitive decline in older adults by stimulating the brain.14

A study shows that the elderly with no social connections are more likely to experience cognitive decline.15

Caring for a Loved One with Alzheimer’s

People with Alzheimer’s suffer from poor memory and it often interferes with their life. You may have difficulty interacting with them since they have trouble remembering things.

Caring for someone with Alzheimer’s, like a loved one, often involves a team. The care you’ll provide depends on which stage your loved one is in.

Early-stage Care

During the early stages of Alzheimer’s, your loved ones can still do things on their own. They can drive, work, and participate in different activities unaided. 

In the early stage, caregivers must slowly prepare themselves for the chronicity of the illness.

The beginning stage can last for years, even decades. You won’t notice any signs during this phase.

Your role as a caregiver is to help them make important decisions about the future, including:

  • Legal
  • Financial
  • Long-term care plans

You must educate other family members about the condition. You must also create a safe space for the person with Alzheimer’s.

Middle-stage Care

The middle stage typically lasts the longest. Your loved one may need greater care as dementia advances. At this stage, various readjustments to ensure safety of the patient must be adressed.

You may notice Alzheimer’s symptoms related to expressing thoughts and doing routine tasks, like:

  • Jumbling words
  • Difficulty dressing up
  • Getting angry and frustrated most of the time

Changes in behavior and communication also need adjustment in their daily care needs. Things may start to become challenging as your loved one may be unable to do things alone or be left alone.

Late-stage Care

The final stage of Alzheimer’s lasts from several weeks to several years. A person in this stage typically loses the ability to talk and communicate their needs.

Eventually, they’ll be unable to walk. They also become susceptible to infections like pneumonia.

Caregiver fatigue must also be addressed at this stage.

During this time, your loved ones need intensive care. You can also expect them to experience difficulties with:

  • Swallowing and eating
  • Walking 
  • Personal care

Your role is to ensure your loved ones maintain their dignity and quality of life. You may also arrange for help when their needs exceed what you can give at home.

The Alzheimer's Association has educational workshops and resources for looking after someone with Alzheimer’s.

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Updated on January 31, 2024
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16 sources cited
Updated on January 31, 2024
  1. Is Alzheimer's Genetic?” Alzheimer’s Association.
  2. What Are the Signs of Alzheimer's Disease?” National Institute on Aging.
  3. Alzheimer's Disease Genetics Fact Sheet.” National Institute on Aging.
  4. Early-Onset Alzheimer’s Disease.” Neurologic Clinics.
  5. Autosomal Recessive Causes Likely in Early-Onset Alzheimer Disease.” JAMA Neurology.
  6. What Causes Alzheimer's Disease?” National Institute on Aging.
  7. Apolipoprotein E and Alzheimer disease: risk, mechanisms, and therapy.” Nature reviews. Neurology. 
  8. Causes and Risk Factors for Alzheimer's Disease.” Alzheimer’s Association.
  9. The Links between Cardiovascular Diseases and Alzheimer's Disease.” Current Neuropharmacology.
  10. Scientists propose new approach to Alzheimer’s research to address environmental risks.” USC News.
  11. Studying neural stem cells could shed light on how environmental aspects interact with genetic risk factors for dementia, says University Professor Caleb Finch.” USC School of Gerontology.
  12. Alzheimer's disease: Can exercise prevent memory loss?” Mayo Clinic.
  13. Alzheimer's prevention: Does it exist?” Mayo Clinic.
  14. Use of Physical and Intellectual Activities and Socialization in the Management of Cognitive Decline of Aging and in Dementia: A Review.” Journal of Aging Research.
  15. You May Lower your Risk for Dementia if you are Socially Active at Age 60.” VanDuyn Center for Rehabilitation and Nursing.
  16. Loneliness and Social Isolation Linked to Serious Health Conditions.” Alzheimer's Disease and Healthy Aging - CDC.
Cristine Santander
Cristine Santander
Content Contributor
Cristine Santander is a content writer for KnowYourDNA. She has a B.S. in Psychology and enjoys writing about health and wellness.
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