Causes and Risk Factors for Alzheimer’s Disease

Billions of neurons in your brain all work together to transmit information. These neurons allow different parts of the brain to communicate with each other and with the rest of your body.

When someone has Alzheimer’s, these neurons become less responsive and lose their connections to each other.

There is some degree of neural loss as we age, but Alzheimer’s disease greatly speeds up the decline. This can result in a large-scale loss of neurons as the disease progresses, making it harder to regain the lost connections and neurons.

While it’s generally understood that the impairment and loss of neurons cause the symptoms of Alzheimer’s disease, researchers are still looking into what causes these changes and why some people develop Alzheimer’s and others do not.

Noticeable changes can be seen when comparing the brain of someone with Alzheimer’s and the brain of someone without the disease. Here are some of the distinct changes present in the brain of someone who has Alzheimer’s:

Amyloid plaques and neurofibrillary tangles

The impairment of neurons for someone with Alzheimer’s begins with a buildup of two major proteins inside and around the edges of the neurons.

One of these proteins is called amyloid, which leaves deposits on the neuron that causes plaque buildup. The other protein is called tau, which leaves deposits inside the neurons that cause tau to accumulate and create tangles. These tangles and buildup interfere with how the neurons send signals.

Chronic inflammation

Glial cells in the brain clear out debris and waste. This includes the type of plaque buildup that develops from amyloid proteins. But in the case of someone with Alzheimer’s, the glial cells simply don’t remove the waste, which causes plaque buildup to worsen.

Glial cells, specifically microglia and astrocytes, collect around the plaque buildup. But instead of removing the buildup, the cells release chemicals that can lead to chronic inflammation in the brain.

Vascular problems

Several vascular issues that affect the blood vessels are also common in the brain and body of a person with Alzheimer’s. Over time, these issues can reduce blood flow and oxygen to the brain and gradually break down the blood-brain barrier.

This barrier keeps out harmful chemicals. But it allows important things like glucose inside while letting proteins like amyloid and tau out. This breakdown of the blood-brain barrier harms its functioning and causes glucose to stay out while keeping tau and amyloid inside.

Other risk factors that are common among those who live with Alzheimer’s, including:

• increasing in age close to 65
• a traumatic brain injury
• cardiovascular disease, which is a disease of the heart and blood vessels
• cerebrovascular disease, which is a disease of the brain and blood vessels
• depression
• having been born to older parents
• family history of dementia
• smoking
• high homocysteine levels
• presence of the APOE e4 allele gene mutation

Still, it is important to remember these are shared factors among some people with Alzheimer’s. Having a few of these factors in your own life does not necessarily mean you will develop Alzheimer’s.

Early onset Alzheimer’s occurs when you begin to experience the symptoms of Alzheimer’s before age 65. While advanced age is one of the largest contributing factors to Alzheimer’s, it is possible to begin experiencing the symptoms of Alzheimer’s earlier in life.

A doctor who specializes in Alzheimer’s disease can evaluate your symptoms and offer a diagnosis. While early onset Alzheimer’s is rare, people have received an early onset diagnosis in their 40s and 50s.

While the causes of early onset Alzheimer’s are unknown, researchers have found that genetics can play a role in some rare cases.

This rare form of Alzheimer’s is called familial Alzheimer’s disease, and it is caused by mutations in the PSEN1, PSEN2, and APP genes.

There’s a 50% chance that people who have this gene mutation will pass it on to their children.

Because there’s so much that remains unknown about Alzheimer’s, it’s easy to see how myths and misinformation can begin to spread. Here are some common questions about the causes of Alzheimer’s:

• Does aluminum cause Alzheimer’s?
• Can Diet Coke cause Alzheimer’s?
• Is Alzheimer’s caused by a bacteria?

The short answer to these questions is no. There isn’t any concrete evidence to support any of these things as definitive causes.

In many cases, there might be a link between one of these things and having dementia later in life. But there is not enough evidence to clearly view it as the cause.

For example, a 2017 study found that recent and frequent consumption of artificially sweetened soft drinks was associated with a higher risk for dementia and ischemic stroke. But researchers didn’t conclude that artificial sweeteners alone caused dementia because the study couldn’t rule out other unknown contributing factors.

One of these unknown factors might be that those participants who have or are at risk of having diabetes chose artificial sweeteners over sugary drinks to reduce their diabetes risk. This means that something like diabetes couldn’t also be ruled out as a potential cause for Alzheimer’s.

Similarly, there is no strong evidence to conclusively show that everyday exposure to aluminum causes Alzheimer’s.

Bacteria also lacks conclusive evidence as a cause of Alzheimer’s.

While a recent study linked gum disease with Alzheimer’s, where plaque from amyloid protein is produced in response to an infection, this should be read with caution because an association does not always mean causation.

Currently, there’s no verifiable method to prevent or delay Alzheimer’s disease. But there are steps to decrease the risk factors that could lead to Alzheimer’s later in life. Here are some actions you could consider:

• If you can, increase your physical activity.
• Keep your blood pressure at a healthy level.
• Consider cognitive training, like reading, playing games, or doing crafts.

There’s no guaranteed way to prevent Alzheimer’s disease. But these lifestyle changes can help reduce your overall risk factors and improve your chances of not experiencing the symptoms of Alzheimer’s later in life.

Alzheimer’s disease is caused by a buildup of proteins in the brain. This buildup slows or stops brain neurons from communicating effectively. As the disease progresses, those brain neurons can even die. Of the people experiencing Alzheimer’s, most are over the age of 65. Still, some people can experience symptoms much younger.

There is no exact known cause for Alzheimer’s. And due to the lack of verifiable evidence, researchers don’t believe aluminum, bacteria, or diet coke can cause Alzheimer’s.

You can take steps today to reduce your risk factors that can lead to Alzheimer’s or other forms of dementia.

While there is no cure for Alzheimer’s, there are many effective treatment options available. As research continues, more discoveries will be made to improve the quality of life for people living with Alzheimer’s disease.