There are many causes of epilepsy, which vary with the age at which seizures begin and the nature of the seizures. However in 50% of cases, the cause is unknown. We know that structural abnormalities in the developing brain, infections such as meningitis or encephalitis, or lack of oxygen to the brain during birth or after a stroke, can cause epilepsy. A brain injury, which results in scar tissue, predisposes individuals to developing epilepsy, although there can be a long period, often years, between the damage occurring and the seizures commencing. Why this occurs, we still do not know. Epilepsy can result from a tumour (an uncommon cause in children) and, in the over 65's from degenerative conditions such as Alzheimer's disease.
Current research has identified that in many cases of epilepsy in very young children, genetics play an important role. But genetics can be a factor in developing epilepsy at any age. It appears that certain people are simply more prone to having seizures than others. This is, at times, described as having a 'low-seizure threshold'. A history of seizures in the family makes it more likely for them to develop epilepsy.