SCIENCE

Air pollution causes Alzheimer's in babies, says study. Danger, Delhi?

alzheimers-reuters An Alzheimer's Disease patient | Reuters

It is estimated that over 3.7 million of India's population suffer from Alzheimer’s Disease—characterised by a slow deterioration of mental and cognitive capabilities—or other forms of dementia. According to reports, the numbers could double by 2030, and even triple by 2050. Yet, awareness of the disease is sadly lacking. A recent research report could trigger alarm bells for Delhi—which had become the most polluted city on Earth last November—as it links air pollution to a possible spurt in the neurodegenerative disease among a generation of growing children.

Lilian Calderón-Garcidueñas, a University of Montana researcher, led a team that studied 203 autopsies of Mexico City residents ranging from the ages of 11 months to 40 years. The researchers specifically looked at levels of two abnormal proteins associated with Alzheimer's—hyperphosphorylated tau and beta amyloid. The bodies, in most cases, displayed heightened levels of these two proteins in the brain, even in children less than one year old. 99.5 per cent of the subjects examined displayed clear evidence of early signs of Alzheimer’s disease.

“Alzheimer’s disease hallmarks start in childhood in polluted environments, and we must implement effective preventative measures early,” says Calderón-Garcidueñas. “It is useless to take reactive actions decades later.”

Some of the health risks of inhaling fine and ultrafine particles are well-established—asthma, lung cancer, and, most recently, heart disease. New evidence suggests that such exposure can also “pollute” the brain, accelerating cognitive aging, and may even increase risk of Alzheimer’s disease and other forms of dementia.

The “ultrafine” particles fall within a broader class of air pollutants commonly referred to as PM2.5. When it comes to toxicity, size actually matters: The smaller the particles that cells are exposed to, a young chemical engineer Arian Saffari says, the higher their levels of oxidative stress, marked by the production of chemically reactive molecules such as peroxides, which can damage DNA and other cellular structures. The pollutant particles destroy the brain by making their way directly to the brain or by triggering the release of inflammatory molecules, attacking it from a distance.

The ALS association defines Alzheimer's as a type of dementia that causes problems with memory, thinking and behaviour. Symptoms of Alzheimer’s usually develop slowly and get worse over time, becoming severe enough to interfere with daily tasks. It is the most common form of dementia, accounting for 60-80 per cent of it.

“Air pollution control has to be prioritised,” said Calderón-Garcidueñas. “Pollution is serious [and] chronic, people are exposed from conception to death.” 

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