Introduction: Definition of Alzheimer’s Dementia

Alzheimer’s disease is the most common type of dementia. The characteristic findings for Alzheimer’s are amyloid plaques and neurofibrillary tangles. Amyloid plaques occur due to abnormally high levels of beta-amyloid, a protein indicative of disease progression.

Beta-amyloid is a naturally occurring protein found between neurons in the brain, but it increases to abnormal amounts in patients with Alzheimer’s. The beta-amyloid proteins clump together with degenerated neurons and other debris, creating amyloid plaques. Neurofibrillary tangles are caused by changes in a protein known as tau. In a normal, healthy state, tau supports the structures in neurons known as microtubules. However, in Alzheimer’s disease, the tau proteins bind to each other instead of the microtubules. This creates tangles of these protein filaments, which disrupts communication between neurons.

As communication is impaired, connections in the brain no longer function, causing them to degenerate. This loss of neural connections leads to many of the symptoms of Alzheimer’s, such as memory loss. Finally, neuroinflammation is another common characteristic. This inflammation is caused by the inability to effectively clear amyloid plaques, toxins, and degenerated neurons tangled in neurofibrillary tangles.

Doctors diagnose dementia through a series of tests, including cognitive tests and brain scans. They then take a detailed medical history and perform a series of memory tests. However, diagnosing the type of dementia can prove to be a challenge. Firstly, they must rule out temporary causes of memory loss, such as medications or disease states. Secondary, they must consider other conditions that present with symptoms similar to Alzheimer’s dementia.

Alzheimer’s Dementia and Epigenetic Changes

Epigenetics involves changes in the expression of DNA without altering the DNA sequence itself. As a result, genes turn off or on. Epigenetic changes are reversible and influenced by external factors, such as the environment and an individual’s diet.

Studies show that epigenetics may play a significant role in Alzheimer’s disease progression. While the research is relatively new in this field, many studies have found an association with epigenetics and many Alzheimer’s disease-related genes. These genes involve the tau protein, amyloid proteins, and glial cells. Glial cells are the support cells in the brain. They are immune cells that usually help clear out toxins and degenerated neurons. Epigenetics may cause these cells to collect tau protein and create tangles similar to neurofibrillary tangles. These changes also impact the ability of glial cells to eliminate toxic amyloid plaques.

Diseases Associated with Epigenetic Changes

Studies show that individuals with type 1 and type 2 diabetes have an increased risk of developing Alzheimer’s disease. Inflammation plays a significant role in developing both diabetes and Alzheimer’s disease. Obesity is a common comorbidity of type 2 diabetes, and visceral fat is a source of systemic inflammation. Type 2 diabetes is also associated with other risk factors for both diseases, such as a diet high in sugars and saturated fats.

Many diseases that affect the heart, such as heart disease, hypertension, and high cholesterol, also have an increased risk of developing Alzheimer’s disease. As the heart supplies blood to the rest of the body, any damage to blood vessels leading to the brain can impact its functioning. Some studies suggest that vascular damage in the brain may worsen Alzheimer’s disease progression more than amyloid plaques or neurofibrillary tangles. Heart disease is also another disease where chronic inflammation is a risk factor.

Dementia: The Role of Prevention

As with many other diseases, lifestyle-related factors such as diet play a significant role in prevention and progression. The Mediterranean diet is best-known for reducing the risk of heart disease and inflammation, both risk factors for developing Alzheimer’s disease. Consequently, this type of diet is effective at lowering the risk of disease progression. The DASH (Dietary Approaches to Stop Hypertension) diet is another successful method to reduce the risk of heart disease and hypertension, making it beneficial for preventing Alzheimer’s.

Mediterranean and DASH diets focus on eating whole foods, natural complex carbohydrates, and avoiding or limiting simple carbohydrates. Simple carbohydrates (i.e., candy, soda, and refined white refined) are highly inflammatory. On the other hand, complex carbohydrates and foods high in fiber, such as whole grains, beans and legumes, and vegetables, have anti-inflammatory properties and lower inflammation in the body. Similarly, saturated fats increase inflammation, while unsaturated fats are highly anti-inflammatory.

The Mediterranean diet places importance on these unsaturated fats, including olive oil, fatty fish such as salmon and mackerel, nuts, seeds, and avocado. The DASH diet tries to limit overall fat intake to reduce blood pressure. Antioxidants found mainly in fruits and vegetables are also highly anti-inflammatory, which both diets recognize. Antioxidants reduce inflammation and neutralize harmful free radicals that cause DNA and cell damage. For a closer look at inflammation, refer to the YHF article on how to reduce inflammation and fireproof your health.

Inflammation and Alzheimer’s Dementia

When our bodies are healthy and not facing any toxins or invading pathogens, we shouldn’t be experiencing any inflammation. Inflammatory genes are suppressed by epigenetic factors that turn the genes “off.” When there are signs of infection or tissue damage, these inflammatory pathways are turned on, and the immune response begins as a regular mechanism. However, inflammation is often unresolved and becomes chronic in diseases such as Alzheimer’s dementia.

As studies show, abnormal epigenetic changes are potentially a significant cause of chronic inflammation. Epigenetic changes in Alzheimer’s affect inflammatory genes and critical genes in the disease pathway, such as the tau protein. Lifestyle factors such as diet and aging (both risk factors for Alzheimer’s) influence these epigenetic changes. The inflammation itself is a characteristic marker for Alzheimer’s— as the brain cannot effectively clear out debris and toxins from amyloid plaques and neurofibrillary tangles, neuroinflammation worsens.

Find out more ways to protect yourself from dementia by reviewing the article on Aging and the Brain: 10 ways to protect it.

References:

1. https://stanfordhealthcare.org/medical-conditions/brain-and-nerves/dementia/types/alzheimers-disease.html

2. https://www.nia.nih.gov/health/what-happens-brain-alzheimers-disease

3. https://www.frontiersin.org/articles/10.3389/fgene.2018.00579/full

4. https://www.alz.org/alzheimers-dementia/what-is-alzheimers/causes-and-risk-factors

5. https://www.alzheimers.org.uk/about-dementia/types-dementia/diagnosing-alzheimers-disease

6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7911414/

7. https://www.alz.org/alzheimers-dementia/research_progress/prevention

8. https://www.doils.net/v1/links/256634.pdf

9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6304253/

10. https://www.ucsf.edu/news/2020/01/416561/distinctive-alzheimers-symptoms-linked-damaged-glial-cells

11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6138241/