Summary: Neurodegenerative disorders like Alzheimer’s and Parkinson’s have risen significantly in the last few decades. Researchers think genes or an aging population alone cannot explain this rise. It appears that pollution plays a significant role in this rise. People are now exposed every day to 80,000 chemicals, and the number is rising. We urgently need to study how these chemicals harm the brain. The focus should be on how genes and the world around us act together.
Finding the cause of brain diseases like Alzheimer’s and Parkinson’s is hard. What keeps puzzling researchers is the significant rise of these diseases. Just imagine: Alzheimer’s was a rare disease only a century ago. Now it is among the leading causes of disability and death, and it affects millions each year.
Genes can explain the risk of Alzheimer’s in some people. But there are many things genes cannot explain. For example, genes cannot explain why so many more people live with Alzheimer’s now than just 50 years ago. The human gene pool has not changed much in the last 50 years.
Look back in time and two big changes over the past century are easy to see. They are how we live and the world around us. Some health experts think changes in the world around us have fed the rise of these diseases. A century ago cars were rare, there were very few polluting industries, and farmers did not even use pesticides. Now all of this happens on a massive scale. Some cities now have more cars than people.
That is why there is new interest in how the world around us drives these brain diseases. A new field of science called exposomics can help. It studies how chemical exposure leads to disease.
At the 2022 annual meeting of the American Neurological Association, one focus was how the exposome (everything we are exposed to) drives brain and nerve disease.
The worry is not just about factory pollution or pesticides. Chemicals are everywhere. They are in the air, the water, and even our food. What is alarming is the sheer number of chemicals the body, and the brain most of all, is exposed to. Some experts estimate there are nearly 80,000 toxic chemicals in the environment. That shows how big and serious the problem is.
Finding out how chemicals raise the risk of brain decline is hard. One way is to compare people exposed to more pollution with people exposed to less. But it is not that simple. Some people never develop a brain or nerve condition even after exposure, because of their genes.
So we need to understand how genes and the environment act together. Researchers also noticed that the problem is not just pollution. There are serious concerns about the growing use of new kinds of nanomaterials (tiny man-made particles). Makers study how these particles behave and bring them into industry. But we know very little about how they may act inside the human body. There are almost no studies of their safety in humans. So industry may be solving one problem while creating others.
It is very clear that genes and older age cannot explain the rise of these brain diseases. Something darker is happening in the background. Exposure to many chemicals is not just high. It is rising at an alarming pace.
Of course, doctors have long known that where we live and work shapes disease. They have always asked patients where they work and live to judge the risk. But even after finding the risk factors, there is not much doctors can do except react. So we need more research on the subject. We also urgently need to teach people and society and to make big changes.
Frequently asked questions
Can pollution cause Alzheimer’s and Parkinson’s disease?
Researchers now think environmental pollutants play a significant role in the rise of Alzheimer’s, Parkinson’s and other neurodegenerative (brain-wasting) disorders. Genes and an aging population cannot explain how fast these diseases have grown. The human gene pool has barely changed in 50 years. Meanwhile, the chemicals we breathe, drink and eat have multiplied. The open question is exactly how each pollutant damages the brain.
What environmental factors are linked to Alzheimer’s disease?
The concern is not only factory pollution or pesticides. Chemicals are everywhere: in the air, in water and in food. Car exhaust has grown on a massive scale, and some cities now have more cars than people. Some experts estimate there are nearly 80,000 toxic chemicals in the environment. And new nanomaterials (tiny man-made particles) are entering industry with almost no human safety studies behind them.
Why are Alzheimer’s and Parkinson’s more common than they used to be?
A century ago Alzheimer’s was a rare disease. Today it is among the leading causes of disability and death, and it affects millions. Genes cannot account for that jump, because our genes have not changed much in 50 years. Two things have changed sharply over the same century: how people live and the world they live in. That includes far more exposure to chemicals.
What is exposomics?
Exposomics is a new field of science. It studies how the chemicals a person is exposed to (the exposome) shape disease. Researchers use it to learn how pollutants feed brain disorders such as Alzheimer’s and Parkinson’s. The American Neurological Association put the exposome on the agenda of its 2022 annual meeting.
Why do some people exposed to pollutants never develop brain disease?
Genes change the risk. Some people exposed to high levels of pollutants never develop a brain or nerve condition because of their genes, while others do. That is why researchers say the real target is how genes and the environment act together, not the chemical alone. Comparing people exposed to more pollution with people exposed to less is only the first step.
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