Epilepsy is a brain disorder that causes repeated seizures—sudden bursts of abnormal electrical activity that can change how a person moves, feels, or behaves. This chronic condition affects around 50 million people worldwide, making it one of the most common neurological diseases. While epilepsy cannot currently be cured, many people can manage their seizures effectively with proper treatment and care.
Epidemiology
Epilepsy affects a significant portion of the world’s population, with approximately 50 million people living with the condition globally. This makes it one of the most common neurological diseases, ranking as the fourth most common neurological condition after migraine, stroke, and Alzheimer’s disease. The widespread nature of epilepsy means that it touches lives across every continent and every community.[1][2]
In the United States alone, about 3 million adults had active epilepsy in 2021, and around 456,000 children aged 17 or younger were living with the condition in 2022. Each year, approximately 150,000 new cases are diagnosed in the United States. Worldwide, about 65 million people have epilepsy, reflecting the global burden of this brain disorder.[3][4]
The distribution of epilepsy is not equal across different parts of the world. Nearly 80% of people with epilepsy live in low- and middle-income countries, where access to proper diagnosis and treatment can be limited. This geographical disparity creates challenges for millions who struggle to receive the care they need.[2]
Anyone can develop epilepsy, regardless of age, race, gender, or ethnic background. However, the condition tends to be more common in certain age groups. Symptoms of epilepsy often start in young children and people over 50 years old, though it can develop at any time during a person’s life. Both males and females are affected equally by this condition.[4][6]
Access to treatment varies dramatically depending on where a person lives. In many low-income countries, three quarters of people with epilepsy do not receive the treatment they need. This treatment gap is particularly concerning because it is estimated that up to 70% of people living with epilepsy could live seizure-free if they were properly diagnosed and treated.[2]
Causes
Epilepsy can develop from many different conditions that affect the brain, though in about half of all cases, doctors cannot identify a specific cause. Understanding what triggers epilepsy in the brain helps researchers and doctors develop better treatments, even when the original cause remains unknown.[3]
When a cause can be identified, it often involves some form of injury or damage to the brain. Traumatic brain injury—damage to the brain from an accident or blow to the head—can lead to epilepsy. Similarly, strokes, which occur when blood flow to part of the brain is blocked, are a known cause of epilepsy, particularly in older adults. Brain tumors can also trigger seizures by disrupting normal brain function.[3]
Infections of the brain can lead to epilepsy as well. Cysticercosis, a parasitic infection, is actually the leading cause of epilepsy worldwide. This infection occurs when people consume food or water contaminated with tapeworm eggs, which then form cysts in the brain. Other infections such as meningitis, encephalitis, and AIDS can also damage the brain in ways that make seizures more likely.[3]
Loss of oxygen to the brain is another important cause. This can happen during birth complications, near-drowning incidents, or cardiac arrest. When brain cells are deprived of oxygen, even briefly, they can be damaged in ways that increase the risk of developing epilepsy later.[3]
Genetic factors play a significant role in some forms of epilepsy. Certain genetic conditions, such as Down syndrome, are associated with a higher risk of epilepsy. In primary generalized epilepsy, where seizures begin on both sides of the brain at once, hereditary factors are particularly important. While epilepsy itself is not contagious and cannot spread from person to person, the genetic tendency to have seizures can run in families.[3][8]
Other neurological diseases can also lead to epilepsy. Alzheimer’s disease and other forms of dementia are associated with an increased risk of seizures, especially as these conditions progress and cause more damage to brain tissue.[3]
Problems during brain development can result in epilepsy as well. Abnormalities in how the brain forms before birth, developmental disorders, or issues with brain wiring can all create conditions where seizures become more likely. An imbalance in the brain’s signaling chemicals, called neurotransmitters, can also contribute to epilepsy by making nerve cells overly active or preventing them from properly regulating their electrical activity.[5]
Less than half of newly diagnosed cases of epilepsy have an identifiable cause. In these situations, doctors diagnose epilepsy based on the pattern of seizures and test results, even without knowing exactly what started the condition. The lack of a clear cause does not prevent effective treatment in many cases.[3]
Risk Factors
While epilepsy can affect anyone, certain factors increase the likelihood of developing this condition. Understanding these risk factors helps people and their healthcare providers watch for early signs and take preventive measures when possible.
Age is one of the most significant risk factors. Children and people over the age of 50 are more susceptible to developing epilepsy. In children, the condition may be related to birth injuries, developmental problems, or genetic factors. In older adults, epilepsy often develops as a result of strokes, brain tumors, or degenerative diseases like Alzheimer’s.[6]
A history of head injury substantially increases epilepsy risk. People who have suffered a traumatic brain injury from accidents, falls, or sports injuries are more likely to develop seizures. The more severe the head injury, the greater the risk becomes.[3]
Having a stroke or experiencing other vascular problems in the brain raises the risk of epilepsy. When blood flow to the brain is interrupted, the resulting damage can create areas that generate abnormal electrical activity.[3]
Infections that affect the brain, particularly in childhood, increase the risk of epilepsy. Meningitis and encephalitis can leave lasting damage that makes seizures more likely. In many parts of the world, parasitic infections like cysticercosis remain a major risk factor for developing epilepsy.[3]
Certain behaviors and circumstances can trigger seizures in people who are already predisposed to epilepsy. Stress, sleep deprivation, and fatigue are common triggers. Not getting enough sleep or having disrupted sleep patterns can lower the threshold for seizures. Consuming alcohol or using illegal drugs can provoke seizures in people with epilepsy. Even insufficient food intake can trigger seizures in some individuals.[8]
Family history matters as well. People with close relatives who have epilepsy have a higher risk of developing the condition themselves, particularly in cases of primary generalized epilepsy where genetic factors play a larger role.[8]
Having certain medical conditions increases epilepsy risk. Genetic conditions like Down syndrome, autism spectrum disorders, and other developmental disabilities are associated with higher rates of epilepsy. People with dementia or Alzheimer’s disease also face increased risk as these conditions progress.[3]
For people who have already had one seizure, the likelihood of having another is significant. About half of people who experience one seizure without a clear cause will have another one, usually within six months. If there is a known brain injury or abnormality, the risk of a second seizure doubles. After two seizures, there is about an 80% chance of having more, which is when epilepsy is typically diagnosed.[8]
Symptoms
The main symptom of epilepsy is having seizures. A seizure is a sudden change in normal brain activity that lasts from a few seconds to a few minutes. What happens during a seizure depends on which part of the brain is affected and how the abnormal electrical activity spreads. Seizures can look very different from one person to another, and the same person may experience different types of seizures.[3]
Many people picture someone falling to the ground, shaking, and losing consciousness when they think of seizures. This type, called a tonic-clonic seizure, does occur, but it is not the most common presentation. During a tonic-clonic seizure, a person’s body becomes stiff, they may fall, their muscles jerk and shake, and they become unconscious. They may also lose control of their bladder or bowels. After the seizure ends, the person typically feels confused, tired, or weak, and may not remember what happened.[6][12]
More often, seizures cause less dramatic symptoms that can be easily missed or misunderstood. A person having a seizure may simply stare into space with a blank expression, appearing to daydream. They might become confused or unable to respond normally to questions. Some people wander around or engage in repetitive movements without being aware of what they are doing.[3]
Absence seizures are particularly common in children and involve brief lapses of awareness that last only seconds, usually less than 10 seconds. During these episodes, a child may stare blankly and show minor muscle movements like eye blinking, lip-smacking, or hand movements. These seizures are often mistaken for daydreaming or lack of attention, which can delay diagnosis.[4]
Some seizures cause unusual sensations or feelings. A person might experience strange smells, numbness, tingling, or changes in vision. They may feel sudden fear or other intense emotions. These symptoms occur when the seizure affects the parts of the brain responsible for processing sensations and emotions.[3][6]
Muscle symptoms vary widely. Some seizures cause specific body parts to jerk or twitch uncontrollably, often starting in the arms or legs. Atonic seizures cause muscles to suddenly go floppy or weak, which can make a person drop things or fall. Tonic seizures make muscles suddenly stiffen, also potentially causing falls. Myoclonic seizures cause brief muscle jerks.[6][12]
Physical injuries can result from seizures. People may fall suddenly and hit their heads or break bones. They can sustain fractures and bruising from injuries related to seizures. Burns can occur if a seizure happens while cooking or near heat sources. These physical problems add to the burden of living with epilepsy.[2]
The awareness level during seizures varies. In focal onset aware seizures, the person remains awake and conscious throughout the episode and can remember what happened. They might experience sensory changes, see flashing lights, feel dizzy, or have uncontrolled muscle jerking, but they know these symptoms are happening. In focal onset impaired awareness seizures, the person is confused or has lost awareness during the seizure. They may display a blank stare or perform repetitive movements but have no memory of the event afterward.[4]
Seizures are classified based on where they start in the brain. Focal seizures begin in one specific area on one side of the brain. Generalized seizures affect widespread areas on both sides of the brain from the start. The type of seizure determines what symptoms appear and how they affect the person.[4]
After a seizure ends, people often experience a recovery period. They may feel tired, sleepy, weak, or confused. Some people recover immediately, while others may take minutes to hours to feel normal again. This recovery period, sometimes called the postictal state, is a normal part of the seizure process.[5]
The frequency of seizures varies tremendously. Some people have seizures very infrequently, perhaps less than once per year. Others may experience multiple seizures every day. The unpredictability of when seizures will occur is often one of the most challenging aspects of living with epilepsy.[2]
Prevention
While epilepsy itself cannot always be prevented, many of the conditions that cause epilepsy can be prevented or managed to reduce risk. Taking steps to protect brain health throughout life significantly lowers the chances of developing epilepsy.
Preventing head injuries is one of the most important measures. Wearing seat belts in vehicles, using appropriate helmets when riding bicycles or motorcycles, and taking precautions to prevent falls—especially in older adults—can all reduce the risk of traumatic brain injury. Safe practices in sports and recreational activities help protect the brain from damage that could lead to epilepsy later.[3]
Preventing strokes through healthy lifestyle choices reduces epilepsy risk in older adults. Controlling blood pressure, managing cholesterol levels, avoiding smoking, maintaining a healthy weight, and exercising regularly all contribute to better vascular health and lower stroke risk. Since stroke is a common cause of epilepsy in people over 50, these preventive measures have significant impact.[3]
Proper prenatal and perinatal care helps prevent epilepsy related to birth complications. Ensuring adequate medical care during pregnancy, monitoring for problems during delivery, and quickly addressing any issues that arise can prevent brain damage from oxygen deprivation. This is particularly important in settings where access to quality obstetric care may be limited.[2]
Preventing and treating infections that affect the brain can reduce epilepsy cases. Vaccinations against diseases like measles and meningitis protect the brain from infections that could lead to epilepsy. In areas where cysticercosis is common, improving sanitation and food safety helps prevent this parasitic infection, which is the leading cause of epilepsy worldwide. Prompt treatment of brain infections when they do occur minimizes lasting damage.[3]
Managing chronic health conditions properly helps prevent complications that could lead to epilepsy. Controlling diabetes, treating high blood pressure, and managing other medical conditions according to doctor recommendations all contribute to better brain health. For people with conditions that increase epilepsy risk, regular monitoring and adherence to treatment plans are essential.[3]
For people already living with epilepsy, preventing seizures through good seizure management is crucial. Taking anti-seizure medications exactly as prescribed is the most important thing a person can do. Skipping doses or stopping medication without medical supervision can trigger withdrawal seizures and worsen the condition. Identifying and avoiding personal seizure triggers—whether stress, lack of sleep, flashing lights, or alcohol—helps reduce seizure frequency.[11]
Maintaining a healthy lifestyle supports overall seizure control. Getting adequate sleep on a regular schedule, managing stress through relaxation techniques, eating a balanced diet, and exercising regularly can all help reduce seizure frequency. Some people find that keeping a seizure diary helps them identify patterns and triggers so they can take preventive action.[18]
Genetic counseling may be appropriate for families with a history of epilepsy, particularly for types known to have a hereditary component. While this does not prevent epilepsy, it helps families understand their risks and make informed decisions.[5]
Pathophysiology
To understand epilepsy, it helps to know how the brain normally works. The brain contains billions of nerve cells called neurons that constantly communicate with each other. These neurons send messages using both electrical signals and chemical messengers called neurotransmitters. The electrical impulses travel in organized, rhythmic patterns that allow the brain to control thoughts, movements, sensations, and all body functions.[4]
In epilepsy, something disrupts this normal electrical activity. Instead of orderly signals, there are sudden, synchronized bursts of electrical energy that spread through groups of brain cells. These excessive electrical discharges happen much faster than normal brain activity—like an unpredictable lightning storm inside the head. This surge of abnormal electrical activity is what causes a seizure.[2][4]
The brain’s electrical rhythms have a tendency to become imbalanced in people with epilepsy. Many neurons fire their signals at the same time, creating a burst of electrical energy that overwhelms the brain’s normal regulation. This synchronized firing spreads the abnormal activity from its starting point to other areas of the brain, depending on the type of seizure.[8]
Different types of seizures reflect different patterns of electrical disruption. In focal seizures, the abnormal electrical discharge begins in one limited area of the brain. The symptoms that appear first often reflect the function of that specific brain area. For example, if the seizure starts in the part of the brain controlling hand movement, the person might first notice their hand jerking. Because the right side of the brain controls the left side of the body and vice versa, a seizure starting on the right side of the brain will affect the left side of the body.[8]
In generalized seizures, the electrical discharge involves both sides of the brain from the very beginning. This widespread involvement explains why generalized seizures often cause loss of consciousness and affect the entire body rather than just one part.[8]
The neurotransmitters in the brain play crucial roles in epilepsy. These chemical messengers either excite neurons, making them more likely to fire, or inhibit them, making them less likely to fire. In a healthy brain, excitatory and inhibitory signals are carefully balanced. In epilepsy, this balance is disrupted. There may be too much excitation, not enough inhibition, or problems with how neurons respond to these signals. This imbalance makes neurons more prone to firing in the abnormal, synchronized patterns that cause seizures.[14]
Anything that disturbs the normal pattern of nerve cell activity can lead to seizures. Physical changes in the brain—from injury, tumors, strokes, infections, or developmental abnormalities—can create areas where electrical activity becomes unstable. Scar tissue in the brain can act as a focus where seizures begin. Chemical imbalances in neurotransmitter levels or problems with the receptors that respond to these chemicals can also make seizures more likely.[5]
During a seizure, the abnormal electrical activity temporarily interrupts the messages being sent between nerve cells. This interruption causes the changes in consciousness, movement, sensation, emotion, and behavior that characterize different seizure types. The specific symptoms depend on which brain areas are affected and whether the person remains aware during the episode.[5]
Between seizures, the brain often functions normally in people with epilepsy, though some may experience ongoing effects. The tendency to have recurrent unprovoked seizures is what defines epilepsy as a condition, even when brain function appears normal between episodes.[2]
Understanding these electrical and chemical disruptions has helped researchers develop treatments that work by stabilizing electrical activity in the brain or by adjusting neurotransmitter levels. Anti-seizure medications target various aspects of this disrupted signaling to help prevent the abnormal bursts of electrical activity that cause seizures.[14]
