Alzheimer’s disease stands as the sixth leading cause of death in the US. So far, no permanent cure has been found for it.
Genetics is known to play an important role in the development and progression of Alzheimer’s. Roughly 75% of dementia cases are caused due to the genetic makeup of the patient.
Research concerning the link between epigenetics and Alzheimer’s disease is in its preliminary stages. But a growing body of research confirms that several environmental factors also contribute to the development of Alzheimer’s disease.
Factors such as the pollution are vital subjects of the research. Hence, when braintests indicate the signs of dementia, there simply isn’t one reason to blame. In this context, this article discusses the role of epigenetics as well as the environment in the development of Alzheimer’s disease.
Epigenetics and the risk of dementia
Studies conducted on post-mortem brain tissues are showing the potential association between Alzheimer’s and epigenetic alteration of gene function. Since the investigation is on people who have succumbed to the brain disease, it is hard for researchers to understand the exact role of epigenetics in developing the neurodegenerative brain disorder.
For instance, experts are not sure if the epigenetics alteration plays a causal role or occurs due to the brain disorder. Some researchers also speculate if the epigenetic changes are just a consequence of aging.
In this study that was conducted by two teams, researchers screened DNA from brain tissues of Alzheimer’s patients. They searched for chemical changes that cause the genes to switch off through methylation.
Such epigenetic alterations do not change the DNA sequence that a person has inherited. Instead, they change the pattern in which genes are expressed, which influences the development of the mental disorder.
The study also found that the greatest methylation differences were in tissues in the entorhinal cortex, the part of the brain that suffers significant damage due to Alzheimer’s. The research witnessed that a gene known as ASK1 correlated with Alzheimer’s.
This gene is responsible for the secretion of ankyrin 1, which is present in the outer membrane of cells and is crucial for maintaining cell structure.
Although the link has been discovered, the exact nature of the gene in the development of dementia is yet to be known.
Additionally, research also sees a link between the symptoms of dementia and an epigenetic enzyme. A decline in one’s learning and memory characterize the early stages of Alzheimer’s
Studies are of the view that increased levels of an enzyme, histone deacetylase 2 (HDAC2), play a role in the development of the degenerative brain ailment. The enzyme helps in controlling the expression of synaptic genes that are related to learning and memory.
Furthermore, an animal study is hopeful that a treatment for Alzheimer’s can be found by restoring this epigenetic balance.
The role of environmental factors in the development of dementia
Numerous environmental aspects play a big role in the development of the degenerative disorder. These include air pollution, exposure to heavy metals, psychological stress and more. Moreover, research confirms that genes remember the negative impact of environmental factors on them and even pass it down to generations.
Let’s take an in-depth look at these factors:
Pesticides and heavy metals
Several studies confirm that exposure to pesticides and heavy metals amps up the risk of neurological disorders.
Long-term exposure to lead correlates to a progressive decline in cognitive functioning. It also negatively impacts memory. Scientific reports also confirm that lead exposure can epigenetically impact newborn children.
Scientists believe that aluminum slows protein metabolism in neurons. It can lead to protein accumulation around brain cells. These can result in the development of beta-amyloid plaques in the brain.
The collection of these plaques is the chief hallmark of Alzheimer’s – the most common type of dementia with 60% – 80% of cases under its belt. What’s more is that exposure to aluminum alters the expression of miRNA numbers too. Unfortunately, aluminum is widely used in various food colorants, food products, and is also used for water purification. The metal is also found in several medications including antacid suspensions.
Furthermore, evidence indicates that prolonged exposure to pesticides leaves toxicity in the central nervous system. Take a look at the graph below. Considering the substantial exposure to pesticides, it is possible that these harmful chemicals can damage the brain significantly.
On top of that, exposure to pesticides negatively modifies our genes as well. A recent study conducted on mice reveals that subjection to the pesticide DDT caused epigenetic modifications, which implicated mice across three generations.
Source: https://infograph.venngage.com/p/246319/3-ways_new
The impact of air pollution
Air pollution has a strong link with epigenetic alteration. It can change DNA tags, which enhances the risk of neurodegenerative diseases like Alzheimer’s. Besides, air pollution separately multiples the risk of dementia. In large cities, the impure air is a blend of metals, gases, and organic and non-organic compounds. Research on the correlation between dementia and air pollution is also growing.
Findings of a study point out that outdoor air pollution can nearly double the risk of dementia in older women. The study also revealed that women who faced exposure to higher markers of PM2.5 showed an increased risk of cognitive decline. They were also more likely to develop dementia.
Statistically, these women had a 92% enhanced risk of developing dementia and 81% higher likelihood of cognitive decline. The study also addressed the role of the gene, APOE4, in causing Alzheimer’s.
It found that women with two copies of the gene had a higher risk of dementia, unlike women with no APOE4 gene.
Lack of sun exposure
Although it would not appear on a dementia test, a lack of exposure to the sun also shoulders the blame of escalated risk of the brain disorder. Sunrays are an abundant source of vitamin D which is responsible for gene expression, brain health, and immune function.
The Scottish Dementia Research Center notes a clear link between dementia and vitamin D deficiency. A 2014 study confirmed that people with a severe lack of vitamin D had a 125% higher risk of developing some form of dementia.
The findings also point to the fact that there’s a threshold level of vitamin D. Below it, the risk for dementia shoots. This threshold is marked at 20 nanograms per milliliter (ng/ml). Besides, vitamin D influences gene expression as well. Researchers claim that vitamin D impacts the placental functioning epigenetically through DNA methylation. This means that a lack of vitamin D leaves a negative imprint on epigenetics and may also increase the risk of dementia.
Head injury
The impact of traumatic brain injuries (TBI) can be significant. In the short run, the effects may be limited to difficulty in reading, trouble speaking, short-term memory issues, and so on. However, in the long haul, a traumatic brain injury can double or quadruple the odds of dementia.
A pivotal study confirmed that senior individuals who suffered from a moderate TBI had 2.3 times increased risk of developing Alzheimer’s. Seniors who experienced severe TBI showed 4.5 times higher chances of having Alzheimer’s dementia, compared to those with no history of TBI.
Lifestyle factors
Another sub-section of environmental factors that influence cognitive health include alcohol consumption, tobacco usage, lack of physical inactivity, and stress. Growing evidence also suggests that these lifestyle factors implicate epigenetic mechanisms like microRNA expression, histone modifications, and DNA methylation.
Alcohol consumption: Heavy alcohol intake corresponds with anxiety and can cause a specific type of dementia known as Wernicke-Korsakoff Syndrome. It is characterized by confusion, memory loss, learning problems, and paralysis of nerves responsible for eye movement.
Tobacco intake: Smoking also increases the risk of developing dementia. A study outlines that smokers have a 45% increased risk of dementia compared with non-smokers.
Exercise: Moderate intensity exercise is critical to fending off the risk of dementia. Research indicates that participants who exercised moderately thrice a week ended up increasing their brain volume by 2%. On the flip side, control group participants lost 1.5% of their brain volume. It explains the impact of a sedentary lifestyle on brain health.
Stress: Chronic stress also works to increase the risk of dementia. A build-up of stress hormones damages cognitive functioning. Emotional distress in young people can snowball their odds of having dementia later on in life. Moreover, stress epigenetically impacts your mental well-being too by altering DNA marks.
Bottom line
Briefly, the role of the environment in the development of dementia is significant. Air pollution, lack of physical activity, stress, exposure to toxic chemicals and metals, and traumatic head injury all contribute to brain damage. All these factors also chip in epigenetic modifications
A single factor is never solely responsible for dementia. Therefore, eat clean, exercise well, indulge in hobbies, meet friends and family members often and overall improve the quality of your life to avoid this neurodegenerative brain disorder.
About The Author
Ashley Rosa
Ashley Rosa is a freelance writer and blogger. As writing is her passion that why she loves to write blogs related to the latest trends in technology and sometimes on health-tech as well. She is crazy about food.
