Some Air Pollutants Linked With Increased Migraine Prevalence, Severity

Ambient air pollutants such as nitrogen dioxide (NO2) and ozone may be associated with increased migraine prevalence and severity, according to research presented at the American Academy of Neurology’s 73rd Annual Meeting, being held virtually April 17-22, 2021.

NO2 is an air pollutant generated from automobiles and fuel combustion. It is also involved in the secondary formation of particulate matter (PM), and even short-term exposure to the pollutant can increase the risk of death from respiratory disease.

Previous research has explored the relationship between the effects of weather on migraine and found that higher relative humidity was associated with greater odds of migraine onset in warm season months. However, one study conducted in 2019 found a weak positive association between air pollutants and higher odds of migraines in the cold season.

To better understand the implications of environmental exposures for migraine in patients in one geographical region, investigators used a migraine probability algorithm (MPA) to assess migraine cases and controls among Sutter Health patients in Northern California.

“Prior studies report associations between fine particles (PM2.5), NO2, and ozone and migraine-related emergency department (ED) visits,” authors wrote. “To our knowledge, none have evaluated the importance of methane super-emitters or oil and gas wells, nor have any considered alternative proxies for migraine exacerbation beyond ED visits,” they added.

Between 2014 and 2018, a total of 89,575 migraine cases were identified at the health system, in addition to 270,564 frequency-matched controls. “Exposures included 2015 annual average block group-level PM2.5 and NO2 concentrations, inverse-distance weighted (IDW) methane emissions from super-emitters within 10km of participant residences between 2016–2018, and 2015 IDW active oil and gas wells within 10km of participant residences,” researchers explained.

To evaluate the association between environmental exposures and migraine case status and severity, researchers used logistic and negative binomial mixed models controlled for age, sex, race/ethnicity, Medicaid eligibility, primary care visits, population density and community poverty. Migraine severity was defined as an MRP score greater than 100, triptan prescriptions, neurologist visits, urgent care migraine visits and ED migraine visits.

Analyses revealed:

• For each 5 parts per billion increase in NO2­, there was a 2% increased odds of migraine case status (95% CI, 1.00-1.05)
• For each 100,000 kg/hour increase in IDW methane emissions, the odds of case status increased (odds ratio [OR] 1.04; 95% CI, 1.00-1.08)
• PM2.5 was linearly associated with neurology visits, migraine-specific urgent care visits, and MPA score >100, but not triptans or ED visits
• NO2­ was associated with migraine-specific urgent care and ED visits, but not other severity measures

Despite these links, overall, researchers “observed limited associations between continuous measures of methane emissions and proximity to oil and gas wells and migraine severity.”

Reference

Elser H, Morello-Frosch R, Jacobson A, et al. Air pollution, methane super-emitters, and oil and gas wells in Northern California: the relationship with migraine headache prevalence and exacerbation. Presented at: American Academy of Neurology 73rd Annual Meeting; April 17-22, 2021; Virtual. Accessed April 20, 2021. https://index.mirasmart.com/AAN2021/PDFfiles/AAN2021-001194.html