Environmental factors in the development of Alzheimer’s disease

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Alzheimer’s disease is one such condition where genetics is known to play a profound role but is not the only factor in the development and progression of the disease. Evidence is mounting that the environment has a lot to do with the development of this neurodegenerative disease. Moreover, it is now known that the right kind of nutrition and lifestyle can play a preventive role in many cases.

Certain environmental factors, such as exposure to toxic chemicals and brain damage, have long been known to increase the risk of Alzheimer’s disease, dementia and Parkinsonism. However, the intricacies of this interaction between environment and genetics are poorly understood. What we know with certainty is that the environment plays an important role in the development of diseases and that certain genes can be predisposing factors.

For example, a gene called APOE4 is thought to be one of the main risk factors in the development of familial Alzheimer’s disease. However, studies have shown the much lower prevalence of Alzheimer’s disease among sub-Saharan Africans compared to Africans living in Western societies, where pollution, industrial food, stress and a sedentary lifestyle make people more susceptible to the disease. There have been very few studies comparing the prevalence of Alzheimer’s disease among genetically similar populations living in completely different environments. One such study compared small-town Nigerians with African Americans and found that the incidence of Alzheimer’s disease was much higher among those who lived in the United States.

Let’s look at the factors that have been strongly linked to neurodegeneration, dementia and Alzheimer’s disease.

Acute exposure and poisoning with heavy metals and pesticides has been well studied and documented. However, neurodegeneration occurs due to chronic low level exposure to these toxic elements. Long-term cumulative exposure to lead has been shown to cause a decrease in memory and a progressive decline in mental functions. Unlike lead, the role of aluminum has long been overlooked. This metal is present in many medications (such as antacid suspensions). Aluminum is an additive in various commercially available food products, food colorings and is even used to purify water. There is growing evidence that it could play a role in the development of Alzheimer’s disease.

Air pollution is something many of us are exposed to from an early age, and in most cases we don’t really have a choice. The polluted air of large cities contains a toxic cocktail of organic and inorganic compounds, metals and gases. Evidence for a link between neurodegeneration and air pollution is mounting.

Unlike in developing countries, non-infectious diseases are the main health threat in Western societies, and an unhealthy lifestyle is the main causative factor for the development of serious chronic diseases. Some estimates suggest that obesity and sedentary lifestyle now kills more people than any other disease. Research data shows that the risk of developing Alzheimer’s disease increases up to 6 times in obese people with high blood pressure and high cholesterol.

Physical activity decreases the risk of almost all diseases, thus having a direct and indirect effect on the development of Alzheimer’s disease as well. Besides physical exercise, it is also important to stay mentally active. Older people who continue to participate in mental activities, such as learning new things, reading or even listening to music have less risk of declining brain function. Social participation can also help keep you mentally active. Many people tend to isolate themselves as they age. However, maintaining a high level of social activity not only decreases stress and improves mood, but may also prevent or delay Alzheimer’s disease and dementia.

Psychological stress causes an increase in the level of stress hormones that have been shown to affect brain function. Emotional distress like depression and anxiety in young and middle-aged adults is thought to increase the risk of developing dementia and Alzheimer’s disease later in life. Some researchers believe that emotional distress could be considered an early symptom of neurodegeneration. There is now a broad consensus that emotional distress is a risk factor for dementia and mental decline.

Nutrition is perhaps the most important factor that can prevent or worsen mental decline. A balanced diet rich in fruits and vegetables is a preventive factor, due to the high content of vitamins, microelements and antioxidants. Diets high in saturated fat and cholesterol are harmful because these fats block blood vessels and cause strokes and heart disease. Since the brain is mainly made up of fat, it is important to have a balanced diet. Omega-3s have been shown to be neuroprotective, and products like fish oil, soybean oil, and nuts are a rich source of this compound.

Family genetic history of neurodegenerative diseases does not necessarily mean that a person will develop mental decline. Neurodegenerative diseases are still largely preventable. By avoiding triggers in the environment and leading a healthy, active lifestyle, one can expect to stay mentally alert well into old age.

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Image via DasWortgewand/Pixabay.

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