Causes of Alzheimer’s Disease

Alzheimer’s disease is a common yet complicated neurodegenerative disorder that contains various factors contributing to its complexity. Furthermore, having a clear understanding of Alzheimer’s causes is extremely important for developing impactful treatments and strategies to prevent the disorder.

How Do Changes In The Brain Cause Alzheimer’s?

There are two key proteins that are believed to interfere with the communication between brain cells in most forms of dementia, including Alzheimer’s; they are called the tau and amyloid proteins. Generally, the tau proteins sit on the inside of neurons, which send and receive brain signals to keep their structure. Maintaining the structure is critical as if it is disrupted, the messages they carry will not reach the next brain cell.

With Alzheimer’s disease, tau proteins are damaged and detach from their full structure. With this change in the brain, the broken tau proteins bundle together and form neurofibrillary tangles. With this dysfunctional structure, the tau protein becomes poisonous to neurons and leads them to die and stop working. Neurons, with the proteins inside them, function in a chain, so when that chain is broken, messages can not be delivered properly within the brain. This break in messages is what causes the struggle to think clearly, which leads to Alzheimer’s disease. ^[1]

The amyloid protein can also cause changes in the brain, which frequently leads to Alzheimer’s. This protein serves two functions. One way is that it produces a healthy digestive protein; the other way is that it can turn into a toxic amyloid-beta. Each of these processes is natural and expected as the harmful amyloid-beta is often cleared from the brain before it can cause serious harm. However, research shows that those suffering from Alzheimer’s disease produce too much amyloid-beta or are less able to overpower it.

This alteration in the brain is highly threatening to the mind as it builds up, creating tiny clusters that turn into large amyloid plaques. The effects of this are an increased amount of abnormal tau proteins, which can continue to activate the toxic amyloid beta, which has no cure. ^[1]

Is Alzheimer’s Disease Genetic?

If you are directly related to someone with Alzheimer’s disease, you are at a higher risk of developing Alzheimer’s, but it does not mean you are guaranteed to get it. With this, those who have two or more first-degree family members with Alzheimer’s are at an even greater risk.

There are a few specific genetic factors in Alzheimer’s to help explain what causes the disease. Risk genes and deterministic genes are the two types of genes that decide your likelihood of obtaining an illness. Studies have shown that both of these genotypes are present in hereditary Alzheimer’s genes. Being related to someone with Alzheimer’s disease is not only disheartening but also concerning for your own health. With this in mind, having a full understanding of your likelihood of developing Alzheimer’s is pivotal, so let’s go into a more detailed overview of hereditary Alzheimer’s.

The most common type of Alzheimer’s disease, late-onset (after 65 years old), is more likely to occur in those who have more than 100 risk genes. Although they raise the chance of getting a disease, risk genes do not ensure that it will happen to you.

Researchers have identified multiple genes that raise the risk of Alzheimer’s. First is the APOE-e4 gene, which continues to have the greatest influence on risk for the majority of the population. Keep in mind that different ethnic and racial groups have different levels of risk, even if they test positive for APOE-e4. Statistics reveal that around 40-65% of people with Alzheimer’s also have the APOE-e4 gene.

The APOE gene comes in three frequent kinds: APOE-e4, APOE-e2, and APOE-e3. Each parent passes down a copy of APOE in one form or another. Alzheimer’s disease is more likely to strike those who receive one copy of APOE-e4 from their parents. Although it is not a certitude, the risk is significantly larger for those who receive two copies from their parents.

To estimate your risk of Alzheimer’s disease, you must take into account a number of differences in APOE-e4 inheritance. Each population has a different APOE-e4 probability. Europeans, for instance, generally have a greater risk than those with some African heritage. The APOE-e4 gene has been linked to the lowest stated risk in several African nations. ^[2]

Does Old Age Cause Alzheimer’s?

Statistics show that the probability of developing Alzheimer’s disease and other forms of dementia increases with age, affecting 1 in 14 people over the age of 65 and 1 in every 6 people over the age of 80. With this, aging is the most prominent risk factor for Alzheimer’s and is characterized by a time-dependent deterioration in the capacity of the mind. Scientific research on the causes and qualities of Alzheimer’s disease is increasing at a fast rate, which is mostly due to the aging population and rising healthcare costs. ^[4]

The complicated cellular background of the brain must be combined with the well-researched molecular changes to successfully understand how aging can cause Alzheimer’s disease. There are various factors of aging that lead to Alzheimer’s, such as the functions of neurons and neural stem cells.

A neuron is a cell in the nervous system that sends signals to the brain, allowing information to pass through. As neurons are fundamental to basic thought and emotion, they are a focus when studying how aging can cause Alzheimer’s.

Research has made it clear that, in some cases, neurons can begin to lose structure and stop working over the age of 65. With this, scientists completed a study comparing the activity of a young person’s neurons with that of an elderly person who has Alzheimer’s. Results showed the brain activity of the child and the elderly person was on a similar level. This study proved that neurons can lose the ability to effectively communicate with the brain, causing a person to struggle with speech, complex thought, movement, and memory (which are all symptoms of Alzheimer’s disease).

Another cause of Alzheimer’s is the deterioration of neural stem cells. Neural stem cells in the adult central nervous system have the capacity to self-renew and produce new neurons over the course of a lifetime. Even in the absence of illness, their capacity to produce new neurons declines with age. Age-related cognitive loss is associated with a decrease in neural stem cell numbers. Therefore, people with Alzheimer’s disease lack the ability to produce new neurons to replace the already damaged ones, eventually worsening the brain disease. ^[3]

Although Alzheimer’s disease predominantly affects people over the age of 65, around 1 in every 13 people with Alzheimer’s are under the age of 65. This is called early-or young-onset Alzheimer’s disease. This is caused by the presence and abnormally fast activity of an APOE-e4 gene. ^[2]

Does Cardiovascular Health Contribute To Alzheimer’s?

One of the main causes of sickness and death among elderly people is heart disease (or cardiovascular disease). Research into what causes Alzheimer’s indicates that Alzheimer’s disease is associated with atherosclerosis, which is a primary cause of cardiovascular disease.

Particularly within the United States, cardiovascular disease is a major public health concern. Approximately 3.7 million Americans who are 65 and older suffered from Alzheimer’s in 2017, and by 2060, that statistic is predicted to rise to 9.3 million. Scientific studies have connected Alzheimer’s to heart disease risk factors such as smoking and lack of physical activity. ^[5]

Therefore, it is critical to keep a healthy heart and take measures to prevent cardiovascular disease, which, in turn, reduces the chance of developing Alzheimer’s disease. How can you do this? To start with, eliminate any bad habits that are known to contribute to cardiovascular disease.

Figures show that a lack of physical activity is plainly linked to a heightened likelihood of cardiovascular disease. A balanced and considerate lifestyle is critical as long periods of sitting and inactivity can both raise the risk of Alzheimer’s and heart disease. Smoking is another well-known risk of cardiovascular disease, and some of the common cognitive changes for people with Alzheimer’s are caused and made worse by smoking.

A higher prevalence of Alzheimer’s has been correlated to excessive smoking in midlife. Smoking can raise the chance of heart disease and Alzheimer’s through a number of pathways, such as greater oxidative stress and disruptions to the proteostasis (protein and nutrient function) system. ^[5]

Other Risk Factors For Developing Alzheimer’s?

There are various risk factors that can explain the causes of Alzheimer’s. Some are more likely to lead to Alzheimer’s disease, but each factor should be taken into consideration to help prevent Alzheimer’s:

• Diabetes – can result in elevated blood sugar levels, which injure brain cells and raise the risk of mental decline by producing blood vessel damage.
• High blood pressure – damages brain blood vessels, lowers blood flow, and causes inflammation, which harms brain cells and raises the risk of cognitive loss.
• Learning disabilities (particularly Down syndrome) – People with Down syndrome suffer from additional health issues and pre-existing diseases that weaken the brain, making it easier for the development of Alzheimer’s disease. ^[6]

Can You Prevent Alzheimer’s?

The prevention of Alzheimer’s disease is being investigated by researchers worldwide. Although there are no proven ways so far to prevent the disease, studies have indicated that you can lower your chance of getting the disease.

Eating a heart-healthy diet can help shield the brain from harm. Limiting sugar and saturated fat consumption while ensuring a diet rich in whole grains, fruits, and vegetables is all part of heart-healthy nutrition. Along with this, frequent exercise is another strategy to prevent your chances of Alzheimer’s.

By improving oxygen and blood flow to the brain, your brain cells remain healthy and intact. Strenuous exercises are not necessary for this; a simple 30-minute brisk walk every day contributes immensely to your physical health. Similarly, taking into consideration the risk factors for Alzheimer’s and actively avoiding them is a simple yet effective way to reduce your probability.

Furthermore, according to several research investigations, preserving close social ties to your friends and family and learning new skills across your lifespan can reduce your probability of cognitive decline.