In over half of epilepsy cases, a cause cannot be found. If there is an identifiable cause, it usually involves the brain being affected by a condition.

The brain is a delicate mix of nerve cells, electrical impulses and chemicals, known as neurotransmitters. Any damage has the potential to disrupt the workings of the brain and cause seizures.

There are two main categories of epilepsy:

• idiopathic (or primary) epilepsy – where no apparent cause for epilepsy can be found, but there may be a family history, suggesting that the condition is inherited
• symptomatic (or secondary) epilepsy – where there is a known cause for a person’s epilepsy

Idiopathic epilepsy

In many cases, no cause of epilepsy is found. This may be because medical equipment is not advanced enough to spot some types of damage, or because the epilepsy has a genetic cause.

Many researchers have suggested that small genetic changes in the brain could be the cause of epilepsy. Current research is looking for defects in certain genes that may affect electrical transmission in the brain.

A number of studies have been carried out; however, no strong association has so far been found between any particular genes and the development of epilepsy.

Symptomatic epilepsy

Causes of symptomatic epilepsy can include:

• cerebrovascular disease (problems with the blood vessels that supply the brain) – such as a stroke or subarachnoid haemorrhage
• brain tumours
• severe head injuries
• drug abuse and alcohol misuse
• infections that can damage the brain – such as meningitis
• problems during birth that cause a baby to be deprived of oxygen – such as the umbilical cord getting twisted or compressed during labour
• some parts of the brain not developing properly

Although some of these problems can cause epilepsy in childhood, symptomatic epilepsy is generally more common in older people – particularly those over 60 years of age.

Seizure triggers

For many people with epilepsy, seizures can occur without any obvious trigger. However, certain circumstances or the use of certain substances can sometimes precede a seizure. These include:

• stress
• lack of sleep
• drinking alcohol
• some medications and illegal drugs
• in women, monthly periods
• flashing lights (this is an uncommon trigger that affects only 5% of people with epilepsy, and is known as photosensitive epilepsy)

Keeping a seizure diary is a good way to help find out what might trigger your seizures. Every time you have a seizure, record it and make a note of what you were doing. Over time, you might notice some potentially avoidable things that seem to trigger your symptoms.