Is Dementia & Alzheimer’s Hereditary? (Do Genetics Play a Role?)

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Whenever a person’s immediate or extended family member is diagnosed with dementia, they wonder, “Will I also develop dementia?”

There is a natural tendency among people to get worried for their kids if one of their family members get diagnosed with dementia. So, what does it imply for other members who might inherit the specific genes if a particular member of the family has been diagnosed with dementia?

The answer to the above question is more or less based on your family history and genetic structure. Further, it also depends on the number of family members affected with Alzheimer’s or other dementia, such as vascular dementia or Lewy body dementia.

You are more likely to inherit Alzheimer’s disease (AD) and other dementias if one or more of your family members were diagnosed with it.

Now the question arises, to what extent may dementia be attributed to family history?

According to the statistics on dementia, genetics play an important role in developing the condition. But they aren’t the only influence. A family history of frontal lobe dementia (also called frontotemporal dementia (FTD) considerably increases one’s risk.

Many inherited illnesses and ailments can be attributed to the majority of the cases discovered so far. One such cause is environmental and lifestyle variables. It may enhance your risk, even if your family history doesn’t have.

In most circumstances, your genealogy will not guarantee that you will develop a disease or specific condition.

But is this true for those who have a family history of dementia?

Yes and no, because the effects of genetics are complicated, and the way heredity is passed down varies. In certain cases of dementia, genetics have a stronger influence on its development than in others.

Let’s go deep into the genetics of dementia and Alzheimer’s disease.

Role of Genetics

Up to 80% of dementia cases may be attributed to Alzheimer’s disease. Hence, it implies that genetics play a similar role in both diseases. Only around 5% of persons with Alzheimer’s disease have early onset, which occurs before age 60. Many single-gene mutations have proven to be directly connected with early onset.

Early onset dementia symptoms are induced by abnormal proteins produced by mutated amyloid beta A4 protein precursor (APP), presenilin 1 (PSEN1), and presenilin 2 genes (PSEN2).

With late-onset type Alzheimer’s disease, no definitive genetic cause for late-onset Alzheimer’s disease has been identified.

However, they discovered a gene mutation that boosts a person’s risk for AD and vascular dementia (VaD). Circulatory disorders impacting memory centers and brain structures cause VaD. Vascular dementia is the second most common type of dementia.

Apolipoprotein E (ApoE) is a genetic variant that codes for a protein that helps remove cholesterol from the body. One study indicated that 25% of the population possessed ApoE4, a variation of the ApoE gene associated with Alzheimer’s disease.

Even though ApoE4 does not directly cause Alzheimer’s or VaD, it may contribute to cognitive decline by causing alterations in the brain.

Although the specific mechanisms by which ApoE4 impacts the brain remain unclear, it appears that individuals with the ApoE4 gene rapidly lose nerve cell functionality in the frontal lobe, an area crucial to preserving higher mental performance. Those with the ApoE4 gene may have accelerated brain aging, which may raise their risk of developing dementia.

The beta-amyloid protein can clump together and block up the gaps between brain cells. ApoE may help break this up. Unfortunately, those who carry the ApoE4 gene variant have a reduced capacity to break down beta-amyloid. The ApoE4 polymorphism has been linked to a higher prevalence of beta-amyloid plaques in the brain.

Numerous studies demonstrate that inheriting two copies of ApoE4 raises the risk of Alzheimer’s. Not everyone with Alzheimer’s has the ApoE4 genetic variant, and not everyone with the mutation will get the disease.

Genetics And The Many Potential Causes of Dementia

Genetics And The Many Potential Causes of Dementia

1. Alzheimer’s Disease

Alzheimer’s disease, the most common dementia, affects millions worldwide. Alzheimer’s is the type of dementia whose genetics are most understood. There are also two distinct forms of Alzheimer’s disease: early-onset and late-onset. These manifest themselves differently in terms of the influence of genetics.

Early-onset Alzheimer’s disease, often called familial Alzheimer’s disease, is believed to be have more of a hereditary link. Any mutation in these three essential genes can be handed down to future generations.

Either of your parents with familial Alzheimer’s has equal risk of passing on the mutation. However, such mutations are rare. It only accounts for a small percentage of Alzheimer’s disease patients.

Late-onset Alzheimer’s disease may be caused by inherited, environmental, and lifestyle factors. Having a relative with late-onset Alzheimer’s disease raises your risk. But it doesn’t indicate whether you will develop it.

So, leading a lifestyle that is beneficial to the health of your heart is crucial.

2. Vascular Dementia

Even though vascular dementia isn’t genetic in most cases, researchers are still looking for risk genes. Currently, genetic variables have been connected to the root causes of vascular dementia.

It’s common knowledge that illnesses like high blood pressure, diabetes, and cholesterol can be inherited from one’s parents or other family members. Because of this, it is extremely important to have a lifestyle that is good for your heart.

In addition, a gene mutation is comparable to the one that causes early-onset familial Alzheimer’s disease. It is thought to be the underlying cause of vascular dementia in exceptional cases.

3. Frontotemporal Dementia And Dementia With Lewy Bodies

The genetics of dementia with Lewy bodies are poorly known, yet again. Rare hereditary instances appear to be strongly connected to one’s family history, much like other kinds of dementia.

Dementia with Lewy body, Parkinson’s disease, and Alzheimer’s disease share symptoms. However, it is unknown if they all result from the same underlying genetic mutation.

About a third of persons with frontotemporal dementia have a personal or family history of the disorder. Dementia is inherited due to a mutation in a single gene, as is the case here.

However, certain forms of dementia are quite rare, so that’s a positive.

4. Familial, Young-Onset Alzheimer’s Disease

There are many different forms of Alzheimer’s disease. The average onset age is in the 80s, although it can occur as early as the 50s and 60s in a tiny percentage of instances. This kind of Alzheimer’s disease is called “young-onset” Alzheimer’s disease.

Approximately 3%, or 1 in every 33 persons, get Alzheimer’s disease before age 60. In these cases, the disease is likely caused by a faulty gene passed down from parents.

Alzheimer’s disease is more likely to be caused by a defective gene in the initial stages of the condition. Thus, it is nearly usually due to a defective gene when a person in their thirties or forties develops Alzheimer’s disease.

Most adults with Alzheimer’s don’t pass on damaged genes to their offspring, but this can happen in younger people.

Rare Forms of Dementia

Huntington’s disease and prion disease are two more rare forms of dementia that can be handed on from generation to generation. However, due to the fact that these conditions are produced by a single defective “dominant” gene, transmission is random.

So, if you receive a healthy gene from one parent and a defective gene from the other, the defective gene will always be utilized since it is the “dominant” gene.

Should You Get Tested?

It is possible to undergo genetic testing to identify whether or not you have inherited any of the genes related to Alzheimer’s disease or other dementias. But, there are both benefits and drawbacks involved with undertaking this process.

Screening for many of the genes associated with the most common types of dementia cannot definitively determine if a person will get a neurodegenerative disorder. So fears may be raised or alleviated by mistake.

Given that there is no medicine to prevent or stop the progression of most types of dementia, genetic screening may be unpleasant and ultimately useless for many. Skipping testing and focusing on mental and physical health may be the best way to decrease changes of developing dementia.

Final Thoughts

Alzheimer’s can affect anyone, notwithstanding family history. Studies show that Alzheimer’s risk increases if a parent or sibling has the disease.

When a person has several close relatives with Alzheimer’s, their risk increases; Alzheimer’s and other dementias may have a genetic or environmental family component.

As previously said, genes only boost the chance of dementia. Good health and lifestyle choices can reduce dementia risk factors like heart disease, diabetes, and smoking.

Dementia risk can be minimized by adhering to a healthy lifestyle. It includes regular exercise, a good diet, moderate alcohol use, and smoking cessation.

References

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