Exposure to polycyclic aromatic hydrocarbons (PAHs) may increase the risk of developing Alzheimer’s disease, a new study suggests.
PAHs are contaminants produced by the burning of carbon-based materials such as coal and oil. They can find their way into what we eat either via the environment from things like cigarette smoke and vehicle exhaust fumes, or during food processing. Some are known to cause respiratory disease and cancer as they can damage DNA.
They can also be produced during cooking, especially from charred or grilled foods.
The study published in the journal Frontiers of Environmental Science and Engineering found the highest concentrations of PAHs in Chinese kitchens, fire stations and ships.
Researchers from Nazarbayev University in Astana, Kazakhstan, and Tokyo University of Science and their teams, collaborated on the study to work out what the molecular interaction is between Aβ polypeptides – the main component of the amyloid plaques found in the brains of people with Alzheimer’s disease – and PAHs.
It is already known that Aβ oligomers – considered upstream triggers of Alzheimer’s disease – may contribute to the development of the progressive, neurodegenerative disease by damaging neurons and disrupting electrochemical signals.
PAHs, including phenanthrene (used to make dyes, plastics and pesticides, explosives and drugs), pyrene (emitted through forest fire, volcanic eruptions, cigarette smoke, and burnt food such as coffee) and benzo[a]pyrene, (found in coal tar, tobacco smoke and grilled meats) increased the aggregation kinetics of Aβ-peptide.
The study reveals that Aβ polypeptides interact strongly with PAHs of different properties, and that these organic pollutants alter the structure of Aβ42, promoting the progression of Alzheimer’s.
The research team found that the structure of Aβ42 peptide monomer was affected by benzo[a]pyrene, nicotine and phenanthrene molecules depending on their hydrophobicity, size, and hydrogen bonding capacity.
Credit: Higher Education Press Limited Company
The secondary structure of Aβ42 peptide was altered by organic pollutants, with an almost 50% decrease in the α-helix and a 2 %–10 % increase in the β-sheets of the peptide.
The team’s results also suggested that benzo[a]pyrene, nicotine, and phenanthrene might have an effect on the progression of Alzheimer’s disease.
While the study doesn’t prove that PAH exposure directly causes Alzheimer’s, it does suggest there may be a link between the two.
The authors write: “Consequently, further in-depth analysis on the effect of organic pollutants on the oligomerization of Aβ peptides would be necessary to gain further insights into the effect of the air pollution on the neurodegenerative diseases.”
There is currently no known cure for Alzheimer’s but there are risk factors that researcher’s already know could increase the chances of developing it.
Uncontrollable underlying characteristics that can influence a person’s possibility of contracting the disease include age, genes, race and gender.
But people do have control over their lifestyle and behaviour which can influence their risk of developing certain diseases.
For Alzheimer’s and related dementias, no behaviour or lifestyle factors have yet come to light that researchers can definitely say contribute to the development of the disease. But in general leading a healthy lifestyle, controlling high blood pressure, exercise, staying mentally active, getting enough sleep, and stopping smoking may help reduce the risk.
Given this latest study it may also be wise to reduce exposure to PAHs – and not just because their impact could be linked to an increased risk of Alzheimer’s, but other diseases too.
This can include avoiding areas with high levels of air pollution, giving up smoking, and reducing the amount of grilled or charred foods in the diet, like meat and vegetables popular at barbecues.