The Effect of Air Pollution on the Development of Dementia in Older People
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THE EFFECT OF AIR POLLUTION ON THE DEVELOPMENT OF DEMENTIA IN OLDER PEOPLE
CHAPTER 1: INTRODUCTION
Background
Air pollution is one of the biggest issues of concern in the 21st century. It refers to the contamination of the atmosphere by biological, chemical or physical substances discharged artificially (Chen et al, 2017). Industrial facilities, home base equipments, motor vehicles, and forest fires, among others are the major sources of pollution. Public health literature has recognized it as a causative factor in a wide range of non-communicable diseases such as cancer, stroke, and coronary artery disease (Alzheimer?s Society, 2020). Pollutants that are of major public health concern are carbon monoxide, ozone, particulate matter, sulfur dioxide and nitrogen dioxide (Alzheimer?s Society, 2020). Particulate matter (PM) has received immense attention in the recent past due to its extreme adverse effects on health (Chen et al, 2017). PM is not a single material; it is a mixture of liquid organic and inorganic matter and fine solids that are dispersed into the atmosphere.
Dementia, which is a disabling degenerative disease, is also becoming increasingly common in the modern society. Recent statistics indicate that around 50 million people worldwide are living with dementia (W.H.O, 2020). Sixty percent of them live in low and middle income nations (W.H.O, 2020). The statistics also indicate that 10 million new cases are recorded every year (W.H.O, 2020). It is estimated that between five and eight percent of people above the age of 60 have dementia currently (W.H.O, 2020). It is projected that the total number of people living with dementia will reach 82 million by 2030 and around 153 million in 2050 (W.H.O, 2020). The association between air pollution and respiratory and cardiovascular diseases is widely documented (Chen et al, 2017). On the other hand, studies that explore the relationship between air pollution and human cognitive functions have been insufficient (Chen et al, 2017). Health research has established a plausible link between the rising cases of air pollution and increased risk of development of dementia among the older people (Chen et al, 2017). The lancet commission on dementia care, prevention, and intervention cited air pollution as one of the high potential risk factors for dementia. According to the commission, there is a building evidence of causation and linked the fine particulate matter, which is the most harmful pollutant, to the development of dementia among the older people.
Researchers have explored the process through which air pollution, especially the particulate matter cause dementia. According to Chen at al. (2017), particulate matter, because of its small size can move from the bronchus to other body organs once inhaled. The pollutant directly affects the skin and the eyes, which is the primary shields of the human body. Choi & Kim (2019) indicate that PM can penetrate through the respiratory tract, triggering health problems. Alzheimer?s Society (2020) argues that inhaled particulate matter travels to the brain tissues through circulation or through the olfactory bulb (Chen et al, 2017). In addition they can cause inflammations in the nasal epithelium and subsequently produce cytokines which can be transmitted to the brain through circulation (Chen et al, 2017). In the older people, who have a high risk of developing dementia, the cytokines lead to the decrease of their overall physiological function with age. On the other hand, young people are able to expel the inhaled particulate matter or eliminate their toxicity within the body(Alzheimer?s Society, 2020). Besides, the older people, especially those who have cardiovascular or respiratory diseases have lower resistance to the biological toxicity of the particulate matter due to lower immunity making them vulnerable to the effects of the matter in the brain (Chen et al, 2017).
Another study indicated that magnetite particles that are released into the air during the burning of fuels can get into the brain (Block, Eder &Auten, 2011). Brain tissues from people in Manchester and Mexico City were analyzed by researchers in 2016 (Block, Eder &Auten, 2011). Using a specialized electron microscope, the researchers explored the surface properties of the magnetite particles, showing that they had been generated in an engine under high temperatures. The study confirmed that fine particulate manner can get to the brain through the blood stream or the nose lining.
Researchers agree that it is possible for pollutants to get to the brain through respiration and circulation. However, they have not provides evidence of how the presence of the pollutants in the brain and the incidence of dementia among the older people (Chen et al, 2017). The aim of this paper is to review the relationship between that pollutant and the onset and development of dementia among the older people (Chen et al, 2017). The purpose of the paper is to conduct a narrative review the evidence base linking the pollutant to cognitive decline and dementia in older people populations (Attademo&Bernadini, 2017). The question addressed by the review is whether there is enough evidence that link air pollution to the incidence of dementia in the older people people and what is the strength of the relationship.
Statement of the Problem
Unlike the relationship between air pollution and the health of the human heart or lung, which is supported by a lot of evidence, the effects of pollution on human cognitive health and brain functions is less clear (Chen et al, 2017). More research is required to clarify this link, its causes and its strength. However, the available evidence makes a strong case for investment into controlled studies that can help in a better understanding of the potential of development of dementia in older people people exposed to pollution (Attademo&Bernadini, 2017). It is worth noting that dementia is caused by a wide range of factors. There are many lifestyle factors that pose a greater risk of the development of dementia in the older people than pollution (Chen et al, 2017). Even though a direct link between dementia and pollution has not been found, studies of dogs and mice that live in polluted environments indicate that air pollution causes cognitive impairment (Chen et al, 2017). Some studies which exposed mice and rats to traffic pollution in a lab setting reported symptoms such as poor motor skills, poor learning ability and low memory (Attademo&Bernadini, 2017). In humans, there is a growing number of studies showing that those who are exposed to pollutants record poor performance on cognitive tests, however, this does not indicate a potential for the development of dementia.
Objective of the research
* To review scholarly evidence in search of the causative link between dementia and air pollution
Research Questions
* What evidence links air pollution to the development or incidence of dementia in the older people
* What is the strength of the link between air pollution and dementia in the older people
Significance of the study
According to the Lancet commission, pollution is the leading environmental cause of diseases and premature death in humans around the world. It is responsible for almost 16 percent of all deaths. Given that pollution is known to cause cardiovascular and respiratory diseases, it is important to evaluate its relationship to other diseases that are related to the circulatory and the respiratory system. Inhaled particles can get to the brain through the nasal epithelium and circulation, meaning that they can affect the cognitive functions. Since a number of studies have explored the impact of pollution on cognitive functions, it is important to review them to test the strength of the link between air pollution and dementia. The study is significant as it will impact on dementia intervention and prevention strategies.
├┐Rationale of the Review
The risk of dementia and associated cognitive decline rises as one ages. The rise in the number of the older people population around the world means that the proportion of people living with dementia is increasing. There are many factors that predispose the older people to the risk of dementia (Weuve et al., 2014). Many of them are lifestyle factors. However, people without the predisposing lifestyle or other known factors have developed dementia (Chen et al, 2017). Therefore, it is important to explore other possible causes and the strength of their link to dementia. Since studies have created a link between air pollution and decline in cognitive functions, it is important for the link between pollution and dementia to be explored. A review of existing evidence can help in establishing the strength of the link and how air pollution ranks as among other predisposing factors.
CHAPTER 2: LITERATURE REVIEW
Introduction
This critical narrative review of literature reviews articles, books, and scientific studies about the relationship between dementia and air pollution. The review starts with the description of dementia, its psychopathology and symptoms. After that, it focuses on the problem of air pollution and its adverse impact in human health, and identifying a possible link to dementia. Various aspects of air pollution and their contribution to the psychopathology of dementia will be examined. The aspects of air pollution that the work will focus on are are oxidative stress, ozone gas, and particulate matter. Particulate matter will be the main focu…