Epilepsy causes recurring seizures, but its effects reach well beyond the seizures themselves. The condition can affect memory, mood, heart function, and overall quality of life depending on the type of epilepsy, how often seizures occur, and which parts of the brain are involved. About 50% of epilepsy cases globally have no identifiable cause, according to the World Health Organization, which means many people living with it are managing effects without a clear underlying explanation.
What Happens During a Seizure
Seizures are the most visible effect of epilepsy, and they look very different depending on where in the brain the abnormal electrical activity starts. At the cellular level, the brain’s signaling system gets thrown off balance. The brain’s main excitatory chemical ramps up while its main calming chemical loses effectiveness. During prolonged seizures, the receptors that normally slow brain activity get pulled inside nerve cells while excitatory receptors move to the surface, creating a feedback loop of overactivity.
Focal seizures start on one side of the brain and can be surprisingly subtle. Some cause a wave of déjà vu or a strange rising feeling in the stomach without any loss of awareness. Others cause confusion, lip smacking, or repetitive picking at clothing, and the person can’t respond to questions for several minutes. Movements typically affect only one side of the body.
Generalized seizures involve both sides of the brain simultaneously. The motor type is what most people picture: loss of consciousness, falling, muscle stiffening and jerking. A person may cry out at the onset. The nonmotor type, called absence seizures, looks completely different. A person stares blankly into space and may blink rapidly or make subtle chewing motions. These episodes are brief and easy to miss, especially in children.
Cognitive Effects
Memory problems are one of the most common and frustrating effects of epilepsy. People with temporal lobe epilepsy tend to experience the most significant memory impairment because the hippocampus, a structure critical for forming and retrieving memories, sits in the temporal lobe and is particularly vulnerable to seizure-related damage. More frequent and longer seizures are associated with greater shrinkage of the hippocampus, which worsens memory over time.
Cognitive problems extend beyond memory. People with epilepsy consistently perform worse on tests of attention, processing speed, verbal fluency, and executive functions like planning and organizing. Those with frontal lobe epilepsy tend to struggle most with complex behaviors: initiating tasks, holding information in working memory, and shifting between activities. The earlier epilepsy begins in life, the greater its impact on working memory and executive function, regardless of how seizures spread through the brain.
One finding that surprises many people: cognitive impairment can appear even in newly diagnosed epilepsy, before medication starts and after only a few recorded seizures. People with no visible structural changes on brain imaging can still show measurable deficits in memory recall, executive function, and processing speed compared to healthy individuals. This suggests that the underlying brain changes driving epilepsy, not just the seizures or medications, contribute to cognitive difficulties from the start.
Depression, Anxiety, and Mood Changes
Epilepsy roughly triples the risk of depression compared to the general population. A large meta-analysis covering over one million people found that about 23% of adults with epilepsy experience active depression. Anxiety disorders affect around 20% of people with epilepsy, with generalized anxiety disorder being the most common type at about 10%. These aren’t simply reactions to living with a chronic condition. The same brain regions and chemical pathways involved in seizures overlap with circuits that regulate mood, meaning epilepsy and psychiatric conditions share biological roots.
Immediately after a seizure, people commonly experience fatigue, headache, difficulty concentrating, speech problems, and abnormal behavior. These post-seizure symptoms are temporary but can last hours, and they compound the psychological burden of the condition over time.
Effects on the Heart and Autonomic Nervous System
Seizures trigger surges in the sympathetic nervous system, the body’s fight-or-flight response. This drives up heart rate and blood pressure acutely, and repeated surges can stress the cardiovascular system over time. Research comparing people with epilepsy to healthy controls has found measurable differences in heart function even between seizures: people with epilepsy tend to have lower resting heart rates and longer QT intervals on electrocardiograms, a marker of altered electrical recovery in the heart.
The autonomic nervous system also controls skin responses and blood pressure regulation, and these show measurable changes in epilepsy. The body’s electrical skin response is slower in people with epilepsy, reflecting broader disruption of how the brain communicates with organs. This autonomic dysfunction is believed to play a role in sudden unexpected death in epilepsy (SUDEP), a rare but serious complication.
Sudden Unexpected Death in Epilepsy
SUDEP is the most severe consequence of epilepsy. It affects roughly 1 in 1,000 adults with epilepsy per year, meaning that in any given year, 999 out of 1,000 adults with epilepsy will not be affected. The risk is lower in children: about 1 in 4,500 per year. SUDEP is not caused by a single mechanism but appears to involve a cascade of events affecting heart rhythm and breathing regulation during or after a seizure. Poorly controlled seizures, particularly generalized convulsive seizures, are the strongest risk factor.
What Prolonged Seizures Can Do
A seizure lasting more than five to ten minutes, or repeated seizures without recovery between them, is classified as status epilepticus. This is a medical emergency. Prolonged seizure activity can cause direct damage to brain cells. Even when seizures are eventually controlled, survivors of prolonged status epilepticus may experience progressive brain shrinkage and lasting functional impairment. The phrase “time is brain” applies here just as it does with stroke: the longer abnormal electrical activity continues, the greater the potential for permanent harm.
Known Causes of Epilepsy
When a cause can be identified, it generally falls into a few categories. Structural causes include anything that physically alters brain tissue: traumatic brain injury, stroke, tumors, or developmental abnormalities present from birth. Hippocampal sclerosis, where one hippocampus shrinks compared to the other, is a common structural finding in temporal lobe epilepsy.
Infections are the most common identifiable cause of epilepsy in many parts of the world. Different infections damage the brain in different ways: some viruses cause tissue death in the brain’s outer layers, bacterial meningitis can block blood flow and cause small strokes, cerebral malaria starves tissue of oxygen, and parasitic infections like neurocysticercosis leave calcified scars surrounded by inflammation.
Genetic causes account for a significant portion of cases. The SCN1A gene is one of the most commonly implicated, with over 1,800 known mutations. About 80% of SCN1A mutations cause Dravet syndrome, a severe form of epilepsy that begins in infancy. But mutations in this same gene can produce a wide spectrum of outcomes, from relatively mild febrile seizure disorders to other serious conditions including Lennox-Gastaut syndrome and West syndrome. Some SCN1A mutations also cause non-epileptic problems like hemiplegic migraine and autism spectrum disorder.
Metabolic causes involve disruptions to the body’s chemical processes that affect brain function. These are often genetic in origin and can cause problems ranging from abnormal cell development to damage of the protective coating around nerve fibers. In these cases, seizures are one symptom of a broader metabolic disorder rather than the primary condition.