What Causes Epilepsy?

Epilepsy is one of the most common brain disorders. About 150,000 people are diagnosed with it each year in the U.S. But doctors aren’t always able to figure out why it happens. In fact, they can't pinpoint the cause of about half of all cases. When the reason for your epilepsy can't be uncovered, that's called cryptogenic epilepsy.

Sometimes, doctors can trace where epilepsy came from or what most likely caused it. Most people get epilepsy either as a child or after age 60. Still, you can get it at any age.

The most common causes include:

Family history. Genes play a big part. As many as 40% of all epilepsy cases happen because the person with it has a genetic makeup that makes them more likely to get it. There isn’t just one gene behind epilepsy. In fact, some experts think there may be as many as 500.

If you have a parent or a sibling with epilepsy, you have a higher chance of getting it than someone who doesn't. Doctors aren’t sure how it’s passed down, but they think it may have something to do with a gene mutation that affects nerve cells in the brain. It’s also possible to have this mutation and never get epilepsy.

Experts think the combination of genetics and something else, like a medical condition, may be to blame.

Head or brain trauma. Either can trigger seizures. Sometimes they go away. If they do, you don't have epilepsy. However, if they continue, that's a sign that you have posttraumatic epilepsy, or PTE. It can also happen after brain surgery. You may not get epilepsy until long after your brain injury -- sometimes years later.

Brain conditions. Most cases of epilepsy in people older than 35 happen because of brain damage from a stroke. Other brain problems that can trigger epilepsy include:

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Infectious diseases. Conditions caused by a viral or bacterial infection can cause epilepsy, too, especially if they infect your brain. Some common culprits are:

Developmental disorders. Certain ones raise your chance of epilepsy, including:

Injury before, during, or soon after birth. Any problems with brain development in the womb or in early infancy raise the chance of epilepsy. Brain damage can happen to babies in the womb for many reasons, including:

  • An infection in the mother
  • Poor nutrition
  • Too little oxygen

If there are problems during birth, or if a baby is born with brain defects, this can also bring on epilepsy.

WebMD Medical Reference Reviewed by Neil Lava, MD on July 11, 2017

Sources

SOURCES:

National Institute of Neurological Disorders and Stroke: “The Epilepsies and Seizures: Hope Through Research.”

Mayo Clinic: “Epilepsy.”

University of Chicago Medicine: “Epilepsy.”

American Academy of Family Physicians: “Epilepsy.”

Cedars-Sinai: “Epilepsy.”

Medscape: “Posttraumatic Epilepsy.”

Epilepsy Society: “Causes of Epilepsy.”

Epileptic Disorders: “Epilepsy in children with Down syndrome.”

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