What Are the Main Causes of Epilepsy?

Epilepsy is a brain disorder that causes repeated seizures due to abnormal nerve activity. In about half of cases, the cause is unknown. For others, epilepsy can be linked to genetic factors, strokes, tumors, or developmental disorders.

Epilepsy can start at any age, including later in life due to infections or traumatic brain injuries (TBIs). Understanding the cause can help guide treatment, but many people manage epilepsy even without knowing the exact reason.

What Is Epilepsy?

Epilepsy is a chronic brain condition that causes repeated seizures. Seizures happen when nerve cells send abnormal electrical signals, temporarily disrupting brain function. This can affect movement, awareness, behavior, or sensations.

Epilepsy is one of the most common neurological conditions, affecting millions of people worldwide. It can develop at any age and occurs in people of all backgrounds. While some cases have a known cause, many do not. A person is diagnosed with epilepsy after having at least two unprovoked seizures more than 24 hours apart.

Although epilepsy is a lifelong condition for some, many people manage their seizures effectively with medication and other treatments. With the right care, most individuals with epilepsy can lead full, active lives.

What Is a Seizure?

A seizure is a sudden, uncontrolled burst of electrical activity in the brain. Normally, brain cells (neurons) communicate in an organized way to control movement, thoughts, and sensations. During a seizure, the brain's signals misfire all at once, briefly disrupting how it works. This can affect awareness, movement, emotions, or behavior for a short time.

Seizures can last from a few seconds to several minutes. They may start in one part of the brain (focal seizure) or affect both sides from the beginning (generalized seizure). Some seizures stay in one area, while others spread across the brain.

Causes

Epilepsy can develop in anyone, regardless of age, gender, or background. In about half of all cases, the cause of epilepsy is unknown, but it can also be linked to various factors that affect brain function.

Some cases of epilepsy are linked to genetic factors, brain structure abnormalities, brain injuries, infections, or developmental disorders. Anything that disrupts normal nerve cell activity can lead to seizures.

Genetics

Genetics can play a big role in epilepsy, especially when it runs in families. Some people inherit epilepsy, while others develop it due to random gene changes (called mutations). However, genes don’t always cause epilepsy on their own—they may just increase the risk, especially if combined with other risk factors like brain injuries or illnesses.

Some types of epilepsy happen because of gene mutations that affect ion channels—tiny pathways in brain cells that help control electrical signals. Other genetic changes can affect how the brain develops, how neurons send messages, or even how someone responds to epilepsy medications.

Some of the most common genetic epilepsies include:

• Dravet syndrome: A severe type of epilepsy that starts in infancy or early childhood. It is often triggered by fever and causes prolonged and frequent seizures as well as other problems with growth and development.
• Juvenile myoclonic epilepsy (JME): A common type that starts in the teen years. It can cause different types of seizure symptoms, ranging from short staring spells, to brief muscle jerks in the upper arms, shoulders, or neck, and more dramatic convulsions.
• Childhood absence epilepsy (CAE): Causes staring spells that last only a few seconds, and is linked to gene changes that affect brain cell activity. Some children with CAE experience other types of seizures that can be more dramatic.

Even though genes can play a role, epilepsy is complicated. Some people with a family history never develop it, while others with no known genetic link still do. Scientists are still studying how different genes may contribute to the condition.

Brain Injuries and Trauma

Up to 6% of all epilepsy cases are caused by a traumatic brain injury (TBI). The risk of epilepsy after a TBI depends on its severity, increasing by 3% for mild cases and up to 16% for more serious brain injuries.

When seizures begin more than a week after a TBI, it’s called post-traumatic epilepsy (PTE). About 80% of people with PTE are diagnosed within two years of their injury. Researchers believe that brain inflammation, nerve cell damage, and changes in brain connections may trigger epilepsy after a TBI.

Seizures after a TBI are grouped into three types:

• Immediate seizures: Instantaneous or within 24 hours of injury
• Early seizures: Within the first week
• Late seizures: More than a week after the injury

Having other risk factors, such as a history of alcohol abuse, smoking, or obesity increases the risk of developing epilepsy after a traumatic brain injury.

Brain Structure Abnormalities

Changes in brain structure can increase the risk of epilepsy by interfering with normal electrical signals. These changes may be present at birth or result from injury, stroke, infection, or tumors.

Common structural causes of epilepsy include:

• Focal cortical dysplasia (FCD): With this problem with brain development, cells don’t form correctly, creating areas that trigger seizures.
• Hippocampal sclerosis: Scarring in the hippocampus, a brain region important for memory, can disrupt normal electrical signals and lead to seizures.
• Brain tumors: Both cancerous and noncancerous tumors can press on brain tissue and disrupt electrical activity.
• Stroke: This is a major cause of epilepsy in older adults, as damaged brain tissue can lead to abnormal electrical activity.
• Perinatal brain injury: Lack of oxygen or bleeding in the brain before or during birth can increase seizure risk.

While structural brain changes can increase the risk of epilepsy, not everyone with an abnormality will have seizures. This depends on factors like genetics, environment, and how well the brain's neurons communicate and regulate electrical activity.

Infections and Illnesses

Infections that affect the brain can lead to epilepsy by causing inflammation, scarring, or structural damage. This is a major cause of epilepsy worldwide, especially in low-resource areas.

Some infections linked to epilepsy include:

• Neurocysticercosis: This parasitic infection from the pork tapeworm Taenia solium forms cysts in the brain and triggers seizures.
• Cerebral malaria: A severe complication of malaria, it can cause brain swelling, coma, and seizures.
• TORCH infections: Infections passed to a baby during pregnancy—such as toxoplasmosis, rubella, and herpes simplex—can lead to seizures, developmental delays, and other brain issues.
• Bacterial meningitis: This bacterial infection inflames the brain and spinal cord. Seizures may occur early on but often stop once the infection is treated.
• Viral encephalitis: This viral brain infection can cause lasting brain damage and increase the risk of epilepsy.
• Tuberculosis (TB): When TB spreads to the brain, it can cause inflammation and seizures.
• HIV/AIDS: HIV/AIDS: The virus itself can cause brain inflammation, and people with HIV are more prone to brain infections that can cause epilepsy like meningitis or encephalitis.

The risk of developing epilepsy depends on the severity of the infection, how the immune system responds, and genetic factors. Early treatment can lower the chances of long-term effects, but in some cases, seizures may appear years after the illness.

Developmental Disorders

Some developmental disorders raise the risk of epilepsy because of brain differences, genetic causes, or problems with brain signals. Seizures are often one of many symptoms.

Developmental disorders linked to epilepsy include:

• Autism spectrum disorder (ASD): Up to 30% of people with autism have seizures, especially those with intellectual disabilities.
• Rett syndrome: A rare genetic disorder that affects brain development, it causes movement and speech problems along with seizures.
• Angelman syndrome: This genetic condition that leads to developmental delays, trouble with movement and balance, and epilepsy.
• FOXG1 syndrome: This severe brain development disorder causes intellectual disabilities, motor issues, and frequent seizures.
• Dup15q syndrome: This chromosomal disorder is linked to autism, intellectual disabilities, and epilepsy.

The risk of seizures depends on the condition. Some disorders change the brain’s structure, while others affect how brain cells work. Treating the main condition may help control seizures.

Alcohol and Substance Use

Alcohol and drugs can trigger seizures and, in some cases, contribute to epilepsy. They may directly affect the brain, cause withdrawal-related seizures, or lead to long-term brain damage.

• Alcohol and seizures: Binge drinking increases the risk of developing seizures, either directly from heavy drinking or during withdrawal.
• Stimulant drugs: Cocaine, amphetamines, and MDMA (ecstasy) can overstimulate the brain and trigger seizures, even in people without epilepsy.
• Benzodiazepine withdrawal: Stopping medications like Xanax or Valium too quickly can lead to seizures.

For people with epilepsy, alcohol and drugs can make seizures worse by affecting medications and raising the risk of seizures. Avoiding these substances helps keep epilepsy under control.

Unknown Causes

In many cases, the cause of epilepsy is unknown. If no clear brain injury, genetic mutation, infection, or other cause is found, it’s called idiopathic epilepsy or epilepsy of unknown origin.

Idiopathic epilepsy often runs in families, suggesting a genetic link, but no single gene causes it. Instead, multiple genes may affect how the brain controls electrical activity. Unlike epilepsy from injury or disease, it usually appears in childhood or adolescence without a clear trigger.

New research in brain imaging and genetics is helping identify causes of unexplained epilepsy. But even without a known cause, treatment can still control seizures and improve quality of life.

Types of Epileptic Seizures

Epileptic seizures are broadly categorized into focal seizures and generalized seizures, based on where they originate in the brain and how they affect consciousness and movement.

Focal Seizures

Focal seizures start in one area of the brain but can affect different parts of the body and consciousness. They can cause changes in awareness, behavior, sensation, or abnormal movements that usually occur on just one side of the body.

There are two main types of focal seizures:

• Focal aware seizures: The person stays awake and aware. They might feel strange sensations, see flashing lights, or have sudden jerking in one part of the body.
• Focal impaired awareness seizures: The person becomes confused or unresponsive. They may stare blankly, make repeated movements like smacking their lips, or seem dazed.

Focal seizures are often barely noticeable. However, the effects depend on which part of the brain is involved and how far the seizure spreads.

Generalized Seizures

Generalized seizures affect both sides of the brain from the start, leading to widespread symptoms. They vary in intensity—some cause brief lapses in awareness, while others result in full-body convulsions.

Healthcare providers use different words to describe generalized seizures, such as:

• Absence seizures: Brief staring spells where the person may seem "zoned out" for a few seconds. These often go unnoticed.
• Tonic seizures: Sudden muscle stiffening, which can cause a person to fall if standing
• Atonic seizures: A sudden loss of muscle tone, leading to a collapse or head drop
• Clonic seizures: Repeated jerking movements, usually in the arms and legs
• Myoclonic seizures: Quick, shock-like muscle jerks, often in both arms at the same time
• Tonic-clonic seizures: The most dramatic type, known as a grand mal seizure. It involves stiffening (tonic phase) followed by full-body jerking (clonic phase), often with loss of consciousness.

Symptoms

Seizure symptoms vary based on the type of seizure. Common signs and warning signals include:

• Staring blankly
• Jerking movements in the arms and legs
• Stiffening of the body
• Passing out or not being aware of what's happening
• Trouble breathing or briefly stopping breathing
• Losing control of the bladder or bowels
• Suddenly falling for no clear reason, especially if unconscious
• Not reacting to sounds or words for a short time
• Looking confused or dazed
• Head nodding in a rhythmic way, especially with loss of awareness
• Rapid eye blinking and staring
• Changes in hearing that might feel like you're underwater
• Distortions in your environment, such as feeling very small or large compared to the things around you
• Déjà vu, a sense that things seem very familiar
• Jamais vu, a sense that things are unfamiliar even if you know them well

During a seizure, a person’s lips may turn blue due to irregular breathing and low oxygen levels. Seizures can be physically exhausting, often leaving the person feeling tired and confused afterward.

Common Triggers

Certain circumstances or situations may increase the likelihood of having a seizure. These are known as triggers, and identifying them can help manage and prevent seizures.

Factors that may contribute to seizures include:

• Sleep deprivation
• Missing or skipping medication
• Illness, with or without fever
• Stress
• Medications that interfere with seizure medication
• Low blood sugar
• Hormonal changes (menstrual cycles, puberty, menopause)
• Flashing lights (photo convulsive epilepsy)
• Certain foods, activities, or noises
• Heavy alcohol use or alcohol withdrawal
• Recreational drug use

When to See a Healthcare Provider

Most seizures are brief and do not require emergency care. However, call 911 immediately if:

• The seizure lasts longer than two minutes.
• The person does not wake up or regain awareness after the seizure.
• The person has multiple seizures in a row without regaining consciousness.
• The seizure happens in water, increasing the risk of drowning.
• The person is injured during the seizure.
• The person has trouble breathing after the seizure.
• It is their first seizure ever.

If you have a seizure, even if it’s short, follow up with a healthcare provider. Your primary care provider can evaluate your symptoms and refer you to a neurologist if needed. A specialist can check your risk of future seizures and decide if treatment is necessary.

Diagnosis

Having one seizure doesn’t always mean you have epilepsy, but the chance of having another within two years is between 21% and 45%. A neurologist can help assess your risk and recommend the right next steps.

To determine if you have epilepsy, a neurologist may perform the following tests:

• Electroencephalogram (EEG): Measures brain activity using electrodes on the scalp to detect abnormal electrical signals
• Prolonged EEG: Continuous video-EEG monitoring over several days in a hospital setting to capture seizure activity
• Magnetic resonance imaging (MRI): Produces detailed brain images to identify structural issues like tumors, scars, or malformations
• Functional MRI: Maps brain functions like speech and memory to assess potential seizure-related areas
• Positron emission tomography (PET): Detects changes in brain metabolism to help locate seizure activity
• Single photon emission computed tomography (SPECT): Captures blood flow changes during and after a seizure to pinpoint affected areas
• Intracranial monitoring: Uses implanted electrodes (depth, strip, or grid) to record brain activity for surgical planning
• Wada test: Temporarily numbs one side of the brain to assess language and memory function before surgery
• Neuropsychological assessment: Evaluates memory, thinking, and cognitive abilities to identify seizure-related brain function issues

Treatment

Anti-seizure medicines help control seizures in about two-thirds of people. Finding the right medicine may take time, and some people need a combination of medications.

Surgery may be an option if seizures come from one specific area of the brain. Removing that area can stop or reduce seizures.

Vagus nerve stimulation (VNS) involves implanting a small device in the chest that sends electrical signals to the brain through the vagus nerve to help prevent seizures.

Responsive nerve stimulation (RNS) is a device placed in the brain that detects seizure activity and stops it with electrical pulses.

A ketogenic diet, which is high in fat and low in carbohydrates, may help when medication and surgery aren’t options. It is usually prescribed for children with hard-to-control seizures and must be monitored by a healthcare provider and dietitian.

Can People With Epilepsy Live a Normal Life?

Most people with epilepsy can live a normal life with the right treatment and lifestyle adjustments. Medications, surgery, or other therapies help control seizures for many. Avoiding triggers, managing stress, and following a healthcare provider’s guidance can improve quality of life.

While some people may face challenges, most can work, drive, and participate in daily activities by collaborating with healthcare providers to manage their condition.

Summary

Epilepsy causes repeated seizures, which happen when the brain's electrical activity is not working normally. Seizures can affect one part of the brain (focal) or both sides (generalized).

Healthcare providers use tests like an EEG, MRI, and PET scan to find out what’s causing them. Treatment includes seizure medicine, surgery, nerve stimulation devices, and special diets. Many people can manage their seizures with the right care, but regular checkups are important.