Memory Loss & the Brain

Epilepsy is a brain disorder characterized by recurrent seizures, which are uncontrolled, excessive electric discharge by the neurons in the brain. The prevalence of seizures is very common; about 1 person in 20 will experience at least one seizure during a lifetime. However, the prevalence of epilepsy -- defined by multiple seizures -- is much smaller: about 1 person in 200. Epilepsy does run in families, although it is unlikely that a single gene accounts for the seizures.

One feature of epilepsy is the individual variation; for example, the interval between seizures may vary from minutes to weeks to even years. Many individuals with epilepsy experience an aura or warning of impending seizure (which may take the form of a sensation such as smell, or may simply be a "feeling" that a seizure is about to occur).

In many cases, epileptic seizures arise from a particular site or "focus" in the brain. When there is such a focus, it is often the medial temporal lobe. Repeated severe seizures can damage the underlying brain tissue. Thus, many individuals who suffer severe epilepsy show cognitive deficits, particularly memory deficits due to damage to the medial temporal lobe.

In many cases, epileptic seizures can be controlled or eliminated by the use of drugs, called anti-convulsant drugs or antiepileptic drugs. In cases where drugs are ineffective and seizures are so severe as to be life-threatening, surgery may be conducted to remove the part of the brain where the seizures arise. The surgery is only done on one side of the brain, leaving the other side intact. The surgery is often very effective, and patients may experience little or no impairments resulting from the lost tissue. (In fact, in some cases, patients appear to show cognitive improvement following surgery - possibly because relief from near-continual seizures allows them to concentrate better.)