Many people with Migraines point to changes in the weather as one of their strongest Migraine triggers. Studies on high barometric pressure, temperature, and humidity have produced contradictory results. Now a study suggests that lightning may well be a trigger.
The study was conducted "to determine if lightning is associated with the frequency of headache in migraineurs."1
- Study participants meeting the International Headache Society criteria for Migraine were recruited from sites in Cincinnati, Ohio, and St. Louis, Missouri.
- There were 23 participants from Cincinnati and 67 from St. Louis, for a total of 90 study participants
- Participants completed a daily Migraine diary for three to six months, including:
- Data on the location, current, and polarity of cloud-to-ground lightning strikes was obtained for the Cincinnati and St. Louis areas for the time period of the study.
- Surface weather variables were recorded hourly from ground stations in the areas. The surface weather variables included:
- dry bulb temperature,
- relative humidity,
- wind speed,
- wind direction,
- barometric pressure,
- and precipitation.
- Data on other weather measurements was also obtained:
- isolation (a measure of solar radiation),
- convection available potential energy (CAPE), and
- lifted index (LI).
- Overall frequency of headache increased by 31% on lightning days.
- Overall frequency of Migraine days increased by 28%.
- Every 20kA decrease in the average current of lightning resulted in a 6% increase in the frequency of headache and an 8% increase of Migraine, indicating that days of lightning strikes with greater negative polarity resulted in increased frequency of Migraine and headache.
- The average current of lightning was significant in predicting headache, but not Migraine.
- Proposed mechanisms by which lightning and its associated meteorological factors could trigger Migraines:
- Low-frequency electromagnetic waves called sferics that are produced by electrical storms.
- Charged ions produced by electrical storms.
- Irritable aerosols that are produced by electrical storms such as nitrogen oxides and ozone.
- Negative ions produced by lightning that could produce more allergenic fungal spores.
* Clarifying headache vs. Migraine: The authors note that the study outcome measure for headache was less stringent than that for Migraine, and that the headache outcome included all headaches, regardless of their characteristics. They believe that both figures reflect Migraine since all of the study participants were Migraineurs, and headaches may have been Migraines that were in their early or late stages. Additionally, they note that early treatment with abortive medications may have prevented some Migraines from fully developing.
The authors concluded: