We know that currently-available anti-epileptic drugs (AEDs) can stop seizures from occurring. However, we don't know much about what they do to the underlying epilepsy condition. Could early treatment with an AED prevent seizures developing in the first place?

Researchers at Yale University School of Medicine, Connecticut, USA, investigated whether dosing rats with ethosuximide (which is used to treat humans with absence seizures) could prevent them developing epilepsy. They investigated this in a breed of rat which has a genetic mutation making them develop absence seizures when about three months old. The researchers treated the rats with ethosuximide from when they were a month old to when they were five months old.

Dr Hal Blumenfeld and his colleagues found that rats treated with ethosuximide did not show the typical changes in brain cell function that are indicative of epilepsy. Though they all had the genetic mutation that normally alters the distribution of a number of ion channels throughout their brains, treatment with ethosuximide had blocked these changes.

The researchers also monitored the rats' epilepsy using EEG recordings at regular intervals. Treated animals had fewer and less severe seizures than untreated animals, and this effect carried on even after treatment with ethosuximide had been stopped. The study was published in the journal Epilepsia in December 2007.

This research shows in principle that it is possible to prevent a genetically-based epilepsy condition from developing, by dosing with an AED before seizures begin. This is the first indication that some types of epilepsy, due to an inherited gene mutation, or possibly due to another cause such as a head injury, may be preventable.

It's likely that in the future, drugs may be designed specifically to prevent seizures from developing in the first place, rather than suppressing them once they've started. However there's a great deal of work to do yet: these results need to be confirmed for other types of epilepsy and with other AEDs, before moving on to trying it in humans.

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