A research conducted by scientists from the US, Mexico and Canada, has determined that the typical air pollution in large cities may impair short-term memory, Intelligence Quotient (IQ) and cerebral metabolic rates. Children particularly are at increased risk for these adverse effects on the brain.
The study by Dr. Lilian Calderon Garcidueñas and colleagues, at the University of Montana in the US, reveals that people who are exposed since childhood and for most of their life to concentrations of air pollutants, exceeding the maximum acceptable levels established by US and other nations, have an increased risk of brain inflammation and neurodegenerative changes, including Alzheimer’s and Parkinson’s.
The researchers found that when air particulate matter and their components such as metals are inhaled or swallowed, they pass through damaged barriers, including respiratory, gastrointestinal and the blood-brain barriers and can result in long-lasting harmful effects.
According to the study, children living in Mexico City had significantly higher serum and cerebrospinal fluid levels of autoantibodies against key tight-junction and neural proteins, as well as combustion-related metals, which is an indicative of damage to their blood-brain barriers. The breakdown of the blood-brain barrier and the presence of autoantibodies to important brain proteins contribute to neuroinflammation.
Interestingly, clinically healthy children living in contaminated environments and who also carry certain variant of the gene APOE epsilon 4, already known for increasing the risk of developing Alzheimer’s disease, show lower cognitive responses compared to children carrying another variant APOE epsilon 3.
The metropolitan area of Mexico City is an extreme example of urban growth and severe environmental pollution, where 8 million children are unintentionally exposed to concentrations of harmful air particles every day since conception.
In the study, published in the Journal of Alzheimer’s Disease, two groups of children living in Mexico City were compared including multiple variables, such as age, gender, socioeconomic status and education, among others. Then, differences between children carrying the variant epsilon 4 with carriers of the epsilon 3 variant were analyzed. They found that the former had three notable changes: They showed short-term memory deficits, an IQ within the normal limits but 10 average points lower, and key metabolic changes in the brain, which resemble those of people with Alzheimer’s disease.
These results reaffirm previous studies suggesting that carriers of variant 4 may be at increased risk of developing Alzheimer’s disease early if living in a polluted urban environment.
Air pollution is a major concern for public health systems worldwide, since exposure to excessive concentrations of air pollutants has been associated with neuroinflammation and neuropathology, as well as increased mortality due to stroke, heart disease and respiratory problems. Mexico City is not a unique environment, several megacities in the world are in the same situation, and many others are approaching. In the US alone, for example, 200 million people live in areas where pollutants such as ozone and other harmful particles often exceed the maximum acceptable standards.
Source: Investigación y Desarrollo (ID)