Neuro effects of pollution tested
Experts say air pollution threatens brain health.
While there has been a lot of focus on the impact of poor air quality on the lungs and cardiovascular system, pollution is now catching the attention of neuroscientists and toxicologists.
Neurotoxicologist Lucio Costa is investigating in a lab set up to mimic the contaminated air someone might breathe while sitting in traffic or living near a busy road.
There is mounting evidence linking a variety of neurological problems to dirty air, including findings of the hallmarks of Alzheimer’s disease in the brains of children living in Mexico City, and a nearly doubled risk of dementias for older women in highly polluted parts of the United States.
Dr Costa’s own research has identified autism-like social and behavioural issues in mice exposed to diesel exhaust. He says such pollution appears to be a pervasive yet overlooked menace to memory, attention, and behaviour.
“There are no death certificates that say air pollution exposure,” says Dr Dean Schraufnagel, a pulmonologist at the University of Illinois at Chicago.
“But we know that air pollution affects every organ in the body. If we stop the air pollution at its source, we can get strikingly important health benefits.”
Studies suggest that tiny PM2.5 particles - which are 30 times smaller than the width of the average human hair - can go up the nose and be carried straight to the brain via the olfactory nerve.
On the surfaces of these PM2.5 particles, they can carry contaminants, from dioxins and other chemical compounds to metals such as iron and lead. In this way, the particulate matter may act as a vector for a number of chemicals to get into the brain and cause damage.
Research shows that small particles can slip through the plasma membrane of alveoli in the lungs and get picked up by capillaries, where they can be distributed around the body in the blood.
This may allow the immune system to react to particles in the lung or bloodstream, triggering widespread inflammation that affects the brain.
Even an ingested particle could have indirect neurological effects, via the gut, due to the strong connections between the gut microbiome and the brain.
A study in the US compared official air quality data to Medicare data for nearly 7 million Americans between 2004 and 2013, some of whom lived in areas with strict PM2.5 regulations while others lived in unregulated areas.
The evidence suggested the regulations had led to nearly 182,000 fewer people with dementia in 2013.
More details are available in a new article for the science journal PNAS.