Prevalence and impact

Epilepsy is a serious, chronic, debilitating, neurological disease affecting people of all ages, ethnicities and socio-economic classes.

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Pubblished: 01/07/2022

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Epilepsy is a serious, chronic, debilitating, neurological disease affecting people of all ages, ethnicities and socio-economic classes.1

Epilepsy is defined by the International League Against Epilepsy (ILAE) as having any of the following conditions:2

  • At least two unprovoked seizures occurring >24 hours apart

  • One unprovoked seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10 years

  • Diagnosis of an epilepsy syndrome

It is characterised by abnormal electrical activity in the brain, that can cause seizures, unusual behaviour or sensations, and sometimes loss of awareness.1

Epilepsy is not a single diagnosis, but a symptom with many underlying causes.3,4 Causes can be grouped into the following aetiologies: genetic, structural, metabolic, immune, infectious and unknown.5,6

Types of epileptic seizure

The International League Against Epilepsy (ILAE) has a working classification of seizures and epilepsy. Seizure classification begins with looking at the area of onset - where the seizure starts in the brain.7

There are three broad types of seizure:7

  • Focal onset

Seizures start in one area of the brain

  • Generalised onset

Seizures affect both sides of the brain at the same time

  • Unknown onset

Seizures where the area of onset is not known

For focal seizures, the level of awareness optionally may be included in the seizure type, and optionally may be further characterised by motor onset or non-motor onset signs and symptoms. The seizure type “focal to bilateral tonic-clonic” is the current term for what was formerly known as “partial onset with secondary generalisation”. Generalised seizures are divided into motor and non-motor (absence) seizures. Seizures of unknown onset may be referred to as “unclassified” or with additional features, including motor or non-motor. 

Prevalence of epilepsy

Accurate estimates of prevalence are difficult because identifying people who may have epilepsy is not straightforward. 

The highest risk of epilepsy is in infants and people over the age of 50 years. New- onset epilepsy in the elderly is increasing.4 People with learning difficulties have higher rates of epilepsy than the general population4 - they make up about 25% of the total of people with epilepsy.4

Around 50 million people worldwide have epilepsy, making it one of the most common neurological diseases.1

Impact of epilepsy

The burden of disease is high.

The lifetime risk of sudden unexpected death in epilepsy (SUDEP) ranges from 10-17% in all epilepsy patients to 10-50% in people who continue to experience seizures.8 SUDEP is the most common cause of premature death among people with epilepsy.Other causes of premature death include accidents such as drowning, motor vehicle and bicycle accidents, status epilepticus, and suicide.10

Common comorbidities suffered by people with epilepsy include memory or attention difficulties, mental health conditions such as depression or anxiety, sleep disorders, and migraines.11

People with epilepsy are more at risk of injury or accidents than people without epilepsy, and the risk is highest in the first two years after seizures start.12

Compared with people with epilepsy who were seizure free*, those whose seizures were poorly controlled (one or more seizures within the past 5 years) were:13

  • >6x more likely to be depressed
  • ~4x more likely to have limitations to usual activities
  • ~3x more likely to have poorer health
  • ~3x more likely to have limited employment
  • 4x more likely to need daily informal help from family/friends
  • 4.5x more likely to be prevented from driving
  • ~2x more likely to have limited education
  • ~3x more likely to have no job or be unable to work
  • >2x more likely to experience stigma/be avoided by others


*No seizures within the last 5 years.13

†Measured using the Health Utility Index, an assessment of health status and quality of life in eight domains (hearing, vision, speech, mobility, dexterity, emotion, cognition, and pain).13

ILAE = International League Against Epilepsy, SUDEP = sudden unexplained death in epilepsy.

  1. Epilepsy: a public health imperative. Geneva: World Health Organization; 2019. Licence: CC BY-NC-SA 3.0 IGO.
  2. Fisher RS, et al. ILAE Official Report. A practical clinical definition of epilepsy. Epilepsia 2014;55(4):475-82.
  3. Nunes VD, et al. Diagnosis and management of the epilepsies in adults and children: summary of updated NICE guidance. BMJ 2012;344:e281
  4. Tidy, C. Epilepsy in Adults. Available at: https://patient.info/doctor/epilepsy-in-adults. Accessed October 2021.
  5. Scheffer IE, et al. ILAE classification of the epilepsies: position paper of the ILAE Commission for Classification and Terminology. Epilepsia 2017;58(4):512-21.
  6. International League Against Epilepsy. Diagnostic Manual: epilepsy etiologies. Available at: www.epilepsydiagnosis.org. Accessed October 2021.
  7. Fisher RS, et al. Operational classification of seizure types by the International League Against Epilepsy: position paper of the ILAE Commission for Classifications and Terminology. Epilepsia 2017;58(4):522-30.
  8. Sowers LP, et al. Sudden unexpected death in epilepsy: fatal post-ictal respiratory and arousal mechanisms. Respir Physiol Neurobiol 2013;189(2):315-23.
  9. Lhatoo S, et al. Sudden unexpected death in epilepsy: identifying risk and preventing mortality. Epilepsia 2015;56(11):1700-6.
  10. Devinsky O, et al. Recognizing and preventing epilepsy-related mortality: a call for action. Neurology 2016;86(8):779-86.
  11. Mula M. The comorbidities of epilepsy explained. Expert Rev Neurother 2020;20(12):1207-9.
  12. Mahler B, et al. Risk for injuries and accidents in epilepsy. Neurology 2018;90(9):e779-89.
  13. Josephson CB, et al. The impact of seizures on epilepsy outcomes: a national community-based survey. Epilepsia 2017;58(5):764-71.

© NICE 2021 Epilepsies: diagnosis and treatment. Clinical guideline CG137. Available at: www.nice.org.uk/guidance/cg137. © NICE 2021 NICE NG27 cost statement. Available at: https://www.nice.org.uk/guidance/ng27/resources/costing-statement-2187244909 All rights reserved. Subject to rights notice. NICE guidelines are produced for the National Health Service in England. All NICE guidelines are reviewed regularly and may be updated or withdrawn. NICE accepts no responsibility for the use of its content in this product/publication.