Air pollution linked to increased risk of Parkinson’s in Italian study
Lower levels of lipoprotein a may also play role in disease risk
Exposure to PM10 — air pollution that can come from wildfire smoke, construction dust, and vehicle exhaust — was associated with an increased risk of developing Parkinson’s disease in a recent Italian study.
Part of the relationship was explained by blood levels of lipoprotein a, which is a protein that transports fats like cholesterol through the bloodstream.
“These findings point towards PM10 as a potential target to lower neurodegenerative risk in the Italian population and warrant further investigations on lipids-related pathways to clarify potential mechanisms underlying PD [Parkinson’s disease] etiology,” researchers wrote.
The study, “Prominent role of PM10 in the link between air pollution and incident Parkinson’s Disease,” was published in npj Parkinson’s disease.
The exact causes of Parkinson’s aren’t fully known, but it’s thought to arise from a combination of genetic and environmental risk factors.
PM10 refers to inhalable particles that are 0.01 mm or less
Over recent decades, exposure to air pollution has emerged as a possible contributor to a variety of diseases, including Parkinson’s. Among the possible culprits is PM10, referring to inhalable particles from things like dust and smoke that are 0.01 mm or less in diameter.
However, findings across different studies vary, and long-term studies carried out in large groups of people are still lacking, making it difficult to fully establish the independent role of air pollutants in driving Parkinson’s disease.
In this study, the scientists evaluated the influence of air pollution on Parkinson’s risk in a large group of 23,841 people from the Molise region in Italy. Yearly exposure to 10 different pollutants was estimated based on the geographical location of each person’s residence.
Over a median follow-up of a little over 11 years, 213 people, or less than 1%, developed Parkinson’s.
This amounted to a standardized incidence of 0.61 annual Parkinson’s cases per 1,000 people in females, 1.04 annual cases per 1,000 males, and 2.4 annual cases per 1,000 people 65 years or older.
A particular group of pollutants, characterized by high exposure to PM10, was significantly associated with an increased Parkinson’s risk even when adjusting for other factors including professional aspects, like exposure to toxic compounds, smoking, and living in urban settings.
The scientists then looked at the relationship between average PM10 exposure and Parkinson’s risk, again revealing that the pollutant was associated with an elevated risk of the neurodegenerative disease.
Particularly, every unit increase in PM10 was associated with an 18% higher risk of Parkinson’s, with the link remaining stable when adjusting for potentially influential lifestyle factors such as alcohol use, diet, physical activity, and body mass index.
People exposed to higher PM10 levels at risk of Parkinson’s
People exposed to PM10 levels above the median level seen across the entire population showed about a 14 times higher risk of Parkinson’s compared with those exposed to lower levels.
Overall, “we identified a significant direct influence of PM10 levels on incident PD risk in an Italian population cohort,” the researchers wrote.
PM10 has been associated with Parkinson’s risk in past studies, but the link has never been definitively established, and not all studies have seen the association, according to the researchers. As such, they recommended “caution in the interpretation of our findings.”
The possible mechanisms through which PM10 might increase the risk of neurodegenerative disease also isn’t known. To learn more, the researchers looked for other factors that could help explain, or mediate, the relationship.
They found blood levels of lipoprotein a explained a small (2.8%), but significant part of the association. Lower levels of the protein were linked to a higher Parkinson’s risk and PM10 exposure.
Some studies have suggested lipoprotein a could play a role in Parkinson’s. While the recent findings indicate the protein “may play a fundamental role in the link between air pollution and neurodegenerative risk,” more studies are needed to understand its specific relationship with PM10 exposure.
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