Adding to the detrimental effects of air pollution, researchers have now suggested that exposure to higher levels of air pollution may increase risk of Alzheimer's disease in those who carry a gene associated with the debilitating brain disorder.
The researchers observed that air pollution has a detrimental impact on cognitive abilities of children carrying a version of the apolipoprotein E gene (APOE) that is associated with the risk for Alzheimer disease.
Lilian Calderon-Garciduenas, professor at Universities of Montana in the US and one of the researchers for the study, said, "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."
The study focused on children between 12 and 16 years of age, with one of their parents sharing the same APOE version of the gene. Investigators looked into the hippocampus, a key structure involved in higher cognitive function, particularly memory processes, and certain affective behaviors. They measured three major brain metabolites in the hippocampus in each child/parent pair using proton magnetic resonance spectroscopy.
The researchers observed that the ratio reflective of neuronal density and functional integrity was significantly decreased in the right hippocampus among children carrying e4 version of the APOE gene and who were exposed to higher level of pollution versus those exposed to low pollution. The team 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.
The researchers said, "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 study was published in the Journal of Alzheimer's Disease.