Air pollution may increase Alzheimer's risk

Higher levels of air pollution may increase risk of Alzheimer's disease in those who carry a gene associated with the debilitating brain disorder, suggests new research.

The researchers detected detrimental impact of air pollution on cognitive abilities of children carrying a version of the apolipoprotein E gene (APOE) associated with the risk for Alzheimer disease (AD).

"These results add to growing data suggesting APOE e4 carriers could have a higher risk of developing early AD if they reside in a polluted urban environment, and unfortunately this statement applies to individuals all around the world with high exposures to air pollutants regardless of ethnicity," said one of the researchers lilian Calderon-Garciduenas, professor at Universities of Montana in the US.

This study focused on children between ages 12 and 16, and one of their parents sharing the same APOE version of the gene. 

Researchers looked into the hippocampus, a key structure involved in higher cognitive function, particularly memory processes, and certain affective behaviors. 

Three major brain metabolites in the hippocampus were measured in each child/parent pair using proton magnetic resonance spectroscopy. 

In the right hippocampus, the ratio reflective of neuronal density and functional integrity, was significantly decreased in children carrying e4 version of the APOE gene who were exposed to higher level of pollution versus those exposed to low pollution. 

Researchers also found that the young children showed evidence of a spectral marker of neurodegeneration that is often seen in adults with mild cognitive impairment, and in Alzheimer patients.

Moreover, these seemingly healthy children have olfaction deficits, dysregulation of feeding regulatory hormones, deficiencies in attention and short-term memory, and below-average scores in verbal and full scale IQ compared to low air pollution children, the researchers said.

The study was published in the Journal of Alzheimer's Disease.