Children and young adults growing up in Mexico City show Alzheimer's and Parkinson's Disease-related symptoms due to air pollution.

If future studies confirm the pioneering finding, it will have global consequences. According to The Guardian, 90 percent of the world's population live in unhealthy air. 

Medical experts are skeptical about the results and said that while the nanoparticles are a probable cause of the injury, it remains to be seen if this contributes to disease later in life.

Previous studies have also shown that air pollution is associated with neurological disease rates. However, a documented causal link has never been demonstrated.

Researchers hope that this research will shed light on a potential physical mechanism that could explain how high pollution levels contribute to an increased risk of Alzheimer's Disease.

Dementia-like grey matter found in brains

As part of the research, scientists dissected the brains of 186 deceased young people from Mexico City who passed away. They range in age from 11 months to the age of 27.

Many of the individuals tested had signs of grey matter contamination and the researchers conclude that after being inhaled into the bloodstream, they penetrated the organ.

In substantia nigra, a region related to Parkinson's disease development, the nanoparticles were discovered.

The particles may also have wormed their way through the nose or gut into the human organs.

However, there was no sign of environmental chemicals in the brains of people who lived in unpolluted places, not in Mexico's smoggy capital.

Professor Barbara Mather of Lancaster University said the research is still observational, and it does not mean causality.

'But how could you expect these nanoparticles containing those metal species to sit inert and harmless inside critical cells of the brain?,' she says.

'That's the smoking gun - it seriously looks as if those nanoparticles are firing the bullets that are causing the observed neurodegenerative damage.'  

Other experts skeptical over results

Although the study is essential and opens up future studies, other scientists took the results with some skepticism.

David Dexter, Associate Director of Research at Parkinson's UK, says that while the study draws on research that connects air pollution to neurodegeneration, brain damage varies substantially from those previously examined.

The latest research authors suggest that the difference in molecular damage might be because the study's specimens were from Mexico City. At the same time, Parkinson's UK brain bank holds organs predominantly from the UK.

Dr Susan Kohlhaas, director of research at Alzheimer's Research UK, said air pollution is related to many adverse health conditions. She added that the risk of developing dementia is correlated with an increasing body of evidence.

"Proteins do build up in the brain years before we see visible dementia symptoms, but more research is needed before we can suggest air pollution drives brain changes associated with disease in children."

Despite not usually suffering from Alzheimer's or Parkinson's, children are valuable for this area of study because their brains are untouched by other variables, such as alcohol, which can be seen in adult organs.

The analysis is published in Environmental Research journal.

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