Alzheimer’s disease (AD) is one of the conditions that humans fear the most. It is horrible enough, for a person to leave the land if the living in an automobile crash or with a sudden heart attack. AD is far worse. People gradually lose their memory, their ability to function, and their very identity, to the ravages of the disease. After decades of study, there is still no consensus on what causes AD, but recent findings are revealing that, unlike infectious diseases that are caused by a single pathogenic agent, there are multiple contributing factors.
One factor is genetics. Alzheimer’s disease and other dementias are known to run in families. There are mutations to a person’s DNA that predispose the person to contracting the disease. However, some family members with those mutations do not get the disease. Another factor is the accumulation of amyloid-beta plaques in the brains of AD patients. However, some autopsies of the brains of deceased people who showed no sign of disease, have also revealed huge aggregations of amyloid-beta plaques.
Recently, air pollution has been identified as another possible contributor to the disease. There are many different kinds of air pollution, including a laundry list of toxic molecules, as well as particles that result from the combustion of gasoline, diesel fuel, coal, and wood. Combustion product particles come in a variety of sizes, including the smallest, called PM2.5, which are smaller than 2.5 micrometers in diameter.
The smaller a particle is, the easier it is for it to slide through a person’s defenses. As anyone who has ever snorted cocaine can attest, the nose is an onramp to the olfactory nerves, which go directly to the olfactory bulb section of the brain. Another possible pathway to the brain is via the optic nerves, which go directly from the eyes to the visual cortex. The irritation of the eyes caused by smog and other kinds of air pollution may be a sign that more is at stake than mere discomfort.
To test the hypothesis that air pollution increases a person’s chance of contracting AD or some other dementia, it would be unethical to run a clinical trial where people were subjected to carefully calibrated levels of air pollution, followed by dissection of their brains. They probably wouldn’t agree to be part of such a trial anyway. Experiments on mice and rats at various research labs, who don’t have any say in the matter, have shown that polluted air pumped into the animals’ cages brought about alterations to the brain and Alzheimer’s-like pathology. Damage also occurred to the vascular system of the animals. An insufficiency of blood flow to the brain can produce additional damage. Damage appeared to be greater in animals that had the APOE4 variant of the APOE gene. The APOE gene is shared by both rodents and humans. APOE4 has been known for some time to be associated with an increased incidence of dementia. Perhaps people who have that variant in their DNA can reduce their chance of dementia by moving to a place with little or no air pollution. A verdant landscape and clear blue skies are great things to have in life. Even better is to have a clear mind. You may not have any control over the genetic hand you were dealt by your parents, but most of us have at least some control over where we live. It might make a big difference in your life to make your abode in a place where the air is fresh and clear.
BIO:
Allen G. Taylor is a 40-year veteran of the computer industry and the author of over 40 books, including Develop Microsoft HoloLens Apps Now, Get Fit with Apple Watch, Cruise for Free, SQL For Dummies, 9th Edition, Crystal Reports 2008 For Dummies, Database Development For Dummies, Access Power Programming with VBA, and SQL All-In-One For Dummies, Third Edition. He lectures internationally on astronomy, databases, innovation, and entrepreneurship. He also teaches database development and Crystal Reports through a leading online education provider. For the latest news on Allen’s activities, check out his blog at wwwallengtaylor.com or contact him at allen.taylor@ieee.org.