Can there be a link between earthquakes and seizures?

Earthquake-prediction techniques could help develop a way to forecast epileptic seizures, according to research which found striking similarities between the electrical activity in the brain before and during seizures and seismological data around earthquakes.

Both are usually preceded by small, barely detectable tremors and, as with an earthquake, the longer it has been since a seizure, the longer it will be until the next one. According to scientists, these shared features mean that the patterns are not random and could even be governed by similar mathematical rules.

Epilepsy comprises a set of conditions which disrupt the electrical activity in the brain and the main symptoms are recurrent, unprovoked seizures. It is one of the most common long-term neurological disorders, affecting 456,000 people in the UK and around 50 million worldwide.

The condition can often be controlled by drugs that damp down the brain's electrical activity, although surgery to remove the affected part of the brain is sometimes used in the most hard-to-treat cases.

Seizures often start suddenly in a region of the brain and can then spread to engulf the organ. An earthquake also appears as a sudden, potentially damaging vibration focused around a relatively well-defined point. The researchers said both seizures and earthquakes could be thought of as "relaxation events", in which accumulated energy is suddenly dissipated.

In their study researchers led by neurologist Ivan Osorio from the University of Kansas showed the frequency of both earthquakes and epileptic seizures could be described by "power laws", which can often explain the frequency of events that, on the surface, seem random. In earthquake prediction power laws link the size of an individual quake with the time that passes between quakes of that size.

Osorio suggested that the similarities between electrical activity in the brain and seismic activity could bring prediction and prevention of seizures a step closer. "This suggests a novel research direction for the prediction of seizures based on the notion that seizures beget seizures," he wrote in a paper uploaded to the Arxiv website, where scientists swap research findings before they undergo peer-review.

Matthew Walker of the experimental epilepsy group at University College London told New Scientist magazine that the research was an "attractive concept", adding that "a good predictive method could revolutionise people's lives". But he cautioned that the Kansas team had yet to show that its method worked in practice.