Low pressure and high humidity—conditions associated with thunderstorms—may put people with epilepsy at higher risk of a seizure. That’s according to a study published online on May 28 in Epilepsia.

Reports of a Weather-Seizure Connection

Epilepsy has a variety of triggers, including sleep deprivation and stress, but many seizures still occur without warning or explanation. Many patients with epilepsy also report anecdotally that bad weather induces seizures. Until now, though, researchers hadn’t investigated the association in a rigorous, long-term study.

Examining Weather’s Effects

To delve deeper into the weather-seizure connection, researchers at several institutions in Germany analyzed the records of patients who had been treated at Jena University Hospital in Jena, a town in central Germany with mild summers and moderately cool winters, between 2003 and 2010. They looked at the records of patients with epilepsy who had been hospitalized for a seizure as well as the records of those without epilepsy, which they used to compare.

The researchers then obtained meteorological records from the Meteorological Monitoring Station of the Jena University of Applied Sciences to determine the hourly ambient temperature, relative air humidity, and atmospheric pressure over the study period. They compared the patients’ hospitalization records with the meteorological data to find possible associations.

Bad Weather Heightens Seizure Risk

The researchers found that people were most likely to experience a seizure during times of high relative air humidity and low atmospheric pressure—conditions that can cause wind, rain, thunderstorms, and even tornadoes.

For people with epilepsy, every 10.7 hPa (hectopascals) lower average daily atmospheric pressure increased their risk of seizure by 14 percent. For people at least 60 years old, the risk was 19 percent. Conversely, high atmospheric pressure, which generally means sunny skies, was associated with a slightly decreased risk of seizures.

For every 18.4 percent higher relative air humidity, seizure risk increased by 22 percent for patients under 60. For those at least 60 years old, the risk increased by 47 over the following three days.

The researchers found no link between zero humidity and seizure risk. In general, patients with less severe epilepsy appeared to be more vulnerable to low atmospheric pressure and high humidity.

Finally, the researchers found that low air temperatures did not have an effect on seizure risk. And temperatures above 20 degrees Celsius (68 degrees Fahrenheit) seemed to have a slightly protective effect against seizures.

Bad Weather or Bad Decisions?

The findings, “suggest a significant association between weather and epileptic seizures,” the authors concluded. However, they cautioned, they weren’t able to tease out whether low atmospheric pressure and high humidity made patients feel depressed or stressed out or less likely to take their anti-epileptic medication or whether those conditions actually caused the seizures.

Still, patients who have epilepsy may want to be extra vigilante about medication and preparing for seizures during bad weather.

Source: Article by: S. Owens for Neurology Now