Epilepsy in Autistic People: One in Ten, Rising to One in Five Adults

Epilepsy is one of the most common health conditions autistic people live with, and one of the most serious. Research pooled from dozens of studies puts it at about one in ten autistic people and close to one in five autistic adults, mostly counting anyone ever diagnosed^[1]. In the general population, on a narrower measure, 4 to 10 in every 1,000 people have active epilepsy at any one time^[2].

Behind those percentages are routines that rarely make the news. It is the parent who has learned to listen for one particular sound in the night. It is the autistic teenager whose first seizure arrives years after their autism diagnosis, just as children's services start to let go. It is the autistic adult with a learning disability whose seizures are described to a doctor by a support worker who has known them for a few weeks. Epilepsy in autistic people is common and can be dangerous, but much of that danger is well understood, and that means much of it can be reduced.

About one in ten autistic people has epilepsy, many times the general-population rate

The most comprehensive recent estimate is a 2022 meta-analysis by Liu and colleagues in Autism, pooling 66 studies published up to 2020. It found epilepsy in 10% of autistic people (95% confidence interval 6–14%): 9% in population-based surveys, 7% in cohort studies and 19% in clinic samples, which are likely to include more people with complex health needs^[1]. An earlier review of 74 studies by Lukmanji and colleagues found a median period prevalence of 12.1%^[4].

WHO estimates that 0.4% to 1% of the general population have active epilepsy at a given time^[2]. Most autism studies count anyone ever diagnosed, a broader measure, so the two cannot be divided into a precise multiple. Where studies compare autistic people with a matched group directly, though, the gap is stark:

• Denmark: of 118 people diagnosed in childhood with infantile autism and followed to a mean age of 42.7, 24.6% had an epilepsy diagnosis in hospital records, against 1.5% of 336 matched controls^[5].
• United States: among Medicare enrollees aged 65 and over in 2016–17, 26.4% of 4,685 autistic older adults had epilepsy, against 1.9% of 46,850 matched comparisons: 18.9 times the odds (95% CI 17.2–20.7)^[6].
• Denmark again: among 4,180 young people diagnosed with Asperger's syndrome, 3.9% had an epilepsy diagnosis by a mean age of 18.1, against the authors' estimate of about 2.0% for the general population of the same age^[7]. The smaller gap is explained below.

The link runs in both directions

Epilepsy services see the overlap from the other side. Lukmanji's review found a median of 9.0% of people with epilepsy were autistic^[4], and a meta-analysis of 19 studies put it at 6.3%^[8]. In a Swedish register study of 85,201 people with epilepsy, 1.6% were later diagnosed as autistic, against 0.2% of matched controls (hazard ratio 10.49, 95% CI 9.55–11.53), with the highest risk when epilepsy began in childhood^[9]. Scotland's autism guideline notes that unrecognised autism in children may first reach services as another problem, such as epilepsy, and says autism "should always be considered as part of a wider clinical presentation, irrespective of the reason for referral"^[10].

Seizures often start in adolescence, and the gap widens with age

For autistic people, epilepsy is not only a childhood condition. In the Liu meta-analysis, pooled prevalence was 7% (95% CI 4–11%) in autistic children and 19% (95% CI 14–24%) in autistic adults, and adolescence was linked to higher prevalence than the school-age years^[1].

Long-term follow-up shows why. In a UK cohort of 150 people diagnosed as autistic in childhood and followed up at 21 or older, 22% had developed epilepsy, and in most of them seizures began after age 10. Generalised tonic-clonic seizures, which affect the whole body, were the main type (88%)^[11]. In the Danish cohort, almost one in four had an epilepsy diagnosis by a mean age of 42.7^[5]; among autistic Medicare enrollees aged 65 and over, more than one in four did^[6]. These studies differ in country, decade and records, so they are not one trend line, but they point the same way.

There is hopeful news too. In the UK cohort, seizures were controlled with one or two anti-seizure medicines in 28 of 31 people^[11], and WHO estimates that up to 70% of people with epilepsy could live seizure-free if properly diagnosed and treated^[2]. Because onset often comes in the teenage years, epilepsy needs to stay on the radar through the move to adult healthcare and into older age.

Intellectual disability is the clearest marker of risk, and autistic girls and women are more affected

The factor most consistently linked with epilepsy in autistic people is intellectual disability. A 2008 meta-analysis by Amiet and colleagues found epilepsy in 21.5% of autistic people with an intellectual disability, against 8% of those without^[12]. A 2012 review by Woolfenden and colleagues found 23.7% in studies where most participants had an intellectual disability and were older than 12, against 1.8% where most did not and were younger^[13]. The Liu meta-analysis and the UK and Danish cohorts point the same way^{[1], [11], [5]}.

That explains the smaller gap in the Danish Asperger's cohort: under ICD-10, Asperger's syndrome was distinguished from autism by the absence of a general delay in language or cognitive development^[14]. But "without an intellectual disability" does not mean "at general-population levels". Amiet's 8% is still well above WHO's range for active epilepsy, although the measures differ^{[12], [2]}.

Several studies also find epilepsy relatively more common among autistic girls and women, which is easy to miss when research samples are mostly male. Amiet found a male-to-female ratio close to 2:1 among autistic people with epilepsy, against 3.5:1 among those without^[12]. Liu, Lukmanji and the UK cohort also linked epilepsy with being female^{[1], [4], [11]}; the Danish infantile-autism cohort did not^[5].

Liu also found epilepsy less common in studies from countries with a high human development index; the reasons are unclear, and could include who gets diagnosed, which studies get done, or care^[1]. Nearly 80% of people with epilepsy live in low- and middle-income countries, and three quarters of those in low-income countries do not get the treatment they need^[2]. Our article on autism and intellectual disability covers the wider health picture for people with both.

Epilepsy is a leading cause of early death for autistic people with an intellectual disability

WHO puts the risk of premature death for people with epilepsy at up to three times that of the general population^[2]. For autistic people, the clearest national evidence comes from Sweden. Hirvikoski and colleagues compared 27,122 people diagnosed as autistic between 1987 and 2009 with 2,672,185 controls matched on sex, age and county. During follow-up, 2.60% of the autistic group died, against 0.91% of controls: 2.56 times the odds (95% CI 2.38–2.76)^[3].

Among the causes of death studied, the odds ratio for diseases of the nervous system was one of the highest: 7.49 (95% CI 5.78–9.72) for autistic people overall, 40.56 (26.82–61.33) for those with an intellectual disability and 3.98 (2.76–5.74) for those without. Epilepsy was the most common cause of death in the group with an intellectual disability^[3].

Denmark adds a nuance. In a cohort of 1.9 million people born between 1980 and 2010, autistic people had twice the mortality risk of non-autistic people through young adulthood (adjusted hazard ratio 2.0, 95% CI 1.5–2.8), though deaths were rare: 68 among 20,492 autistic people. Among people with a neurological condition, being autistic added no measurable extra risk (adjusted hazard ratio 0.7, 95% CI 0.4–1.3), and the authors suggest the mechanisms "may be mediated through or shared with neurologic or mental/behavioral disorders"^[15]. That does not make autism irrelevant. It does suggest that conditions such as epilepsy are a large part of where the excess risk shows up, and those are conditions health services know how to treat and monitor. See also our article on the autism mortality gap.

SUDEP: what is known, and what is missing

Sudden unexpected death in epilepsy (SUDEP) is the sudden, unexpected death of a person with epilepsy, with or without a seizure, not caused by injury or drowning, where a post-mortem finds no structural or toxicological cause^[16]. A 2017 guideline from the American Academy of Neurology and the American Epilepsy Society put it at about 1 in 4,500 children and 1 in 1,000 adults with epilepsy each year, and states that seizure freedom, "particularly freedom from GTCS" (generalised tonic-clonic seizures), "is strongly associated with decreased SUDEP risk"^[17].

We did not find a population study reporting SUDEP rates for autistic people as a group. The nearest evidence concerns people with an intellectual disability, a group that includes many autistic people with epilepsy: in a study of 904 such adults across England and Wales, 37% were autistic^[18]. In Leicestershire, England, SUDEP was the second most common cause of death among adults with an intellectual disability and epilepsy between 1993 and 2010. Standardised mortality ratios for SUDEP, against the general population, were 37.6 for men (95% CI 21.9–60.2) and 52.0 for women (95% CI 23.8–98.8), based on 26 deaths. In most of these deaths there had been no communication with the person or their carers about SUDEP risk^[19].

Part of the reason the evidence is thin is that autism is often invisible in death records. In a US study following 23,393 autistic young people identified through CDC surveillance, only 11% of those who died had autism coded on their death certificate^[20]. Deaths that go uncounted cannot be studied.

What joined-up care looks like, on paper and in practice

We found no guideline devoted to epilepsy care for autistic people. Epilepsy guidelines that address people with an intellectual disability, SUDEP guidance and autism guidelines together describe what good care should include.

Guidance	What it asks for
SIGN 143, Scotland (adult epilepsy, 2015, updated 2018)	People with a learning disability get the same range of investigations and treatment as everyone else; enough consultation time; accessible information; a multidisciplinary team with epilepsy expertise; aiming for complete seizure freedom; SUDEP counselling to be considered for people with epilepsy, at an appropriate time[16]
American Academy of Neurology and American Epilepsy Society (2017)	Tell people with epilepsy, and parents, about SUDEP and how often it happens; explain that seizure freedom is strongly associated with lower SUDEP risk[17]
ILAE Task Force on Intellectual Disabilities and Epilepsy (2014)	Standards for diagnosis and treatment, including rescue medication; multidisciplinary teamwork and better communication; links between health services, schools, employment services and families[21]
SIGN 145, Scotland (autism, 2016)	In autism assessment, epilepsy is common but an EEG is not indicated without other clinical grounds; treatment of co-occurring conditions such as epilepsy is outside its scope[10]

UK data show the gap between standards and practice. Among the 904 adults with an intellectual disability and epilepsy, over 90% had had an epilepsy review in the past year, yet 25% had no epilepsy care plan and only 61% had a documented SUDEP discussion, with both gaps wider for people with a mild intellectual disability^[18]. A related case-control study by the same team compared 190 people with an intellectual disability and epilepsy who had died with 910 living controls. Those who died were less likely to have had an epilepsy risk assessment, and having no epilepsy review in the previous 12 months was associated with higher risk of death^[22]. Neither study reports results for autistic people separately.

What the evidence asks of us

The research does not ask for anything exotic. It asks health systems to apply, reliably and for autistic people, standards they have already written down.

• Treat epilepsy as core autistic healthcare, for life. Prevalence rises into adulthood and stays high in older age^{[1], [6]}, so adult and older-age services need it on their radar, not only children's services.
• Make care plans and SUDEP conversations universal. Guidelines recommend SUDEP counselling^{[16], [17]}, and Scotland's says that where a care plan is needed it should be used by everyone working with the person and reviewed regularly^[16], yet a quarter of adults in a large UK cohort had no care plan^[18].
• Guarantee equal access to treatment. People with a learning disability should have "the same range of investigations and treatment as the rest of the population"^[16].
• Join up autism and epilepsy care. Scotland's autism guideline leaves epilepsy treatment out of scope^[10], while the ILAE task force calls for multidisciplinary teamwork^[21]. Commissioners can build pathways where autism teams, epilepsy nurses, learning disability services and families share one plan.
• Count autistic people properly. Record autism in epilepsy services and on death certificates^[20], and fund research on SUDEP in autistic people, on autistic adults without an intellectual disability, and in low- and middle-income countries^[2].

Autistic people and their families already do much of the daily work of living with epilepsy. The evidence says health systems can share more of it, and that doing so would save lives.

Language: this piece uses identity-first language ("autistic people"), the preference of most autistic-led organisations, and uses clinical terms such as "autism spectrum disorder" only when naming a study or diagnostic category. Older labels such as "infantile autism" and "Asperger's syndrome" are kept where a study used them.

Why we're publishing this

Health Insurance UK is a commercial health-insurance resource, not a charity and not a campaign. We compiled this evidence because autistic people, families and autistic-led organisations pushing for better epilepsy care deserve the numbers clean, sourced and in one place, ready for a commissioner, a clinical lead, an MP or a journalist. The case is theirs. Our part is to say plainly what the research shows: epilepsy is common among autistic people, becomes more common with age, and is a leading cause of early death for autistic people with an intellectual disability. Guidelines already describe how to reduce that risk.

How to read this data

Most figures come from meta-analyses of studies of varying quality, national registers in Denmark and Sweden, US insurance claims and UK clinical cohorts. Autism studies mostly count anyone ever diagnosed with epilepsy, while WHO's figure counts active epilepsy, so they are not like-for-like. Clinic samples give higher estimates than population surveys. Because intellectual disability is linked to both epilepsy and mortality, results for autistic people as a whole depend on how many participants had one. Mortality figures are odds ratios, hazard ratios or standardised mortality ratios, as labelled, and show associations, not causes. SUDEP evidence specific to autistic people is thin, and most research comes from high-income countries. For several studies only the abstract was available, and we have used only what it reports.

Use this data

Free to cite with attribution to Health Insurance UK. Charities, campaigners and journalists are welcome to reuse these figures and charts. For the underlying figures as a spreadsheet, get in touch. More articles are in our Autism & Health research library.

Important: This article summarises published research for general information. It is not medical advice and cannot be used to diagnose, treat or predict anything about an individual. If you have concerns about your own or someone else's health, please speak to a qualified health professional.

Sources

1. Liu X, Sun X, Sun C, Zou M, Chen Y, Huang J, Wu L, Chen WX. Prevalence of epilepsy in autism spectrum disorders: a systematic review and meta-analysis. Autism 26(1):33–50, 2022. eric.ed.gov/?id=EJ1324101
2. World Health Organization. Epilepsy (fact sheet, 7 February 2024). WHO, 2024. who.int/news-room/fact-sheets/detail/epilepsy
3. Hirvikoski T, Mittendorfer-Rutz E, Boman M, Larsson H, Lichtenstein P, Bölte S. Premature mortality in autism spectrum disorder. British Journal of Psychiatry 208(3):232–238, 2016. doi.org/10.1192/bjp.bp.114.160192
4. Lukmanji S, Manji SA, Kadhim S, Sauro KM, Wirrell EC, Kwon CS, Jetté N. The co-occurrence of epilepsy and autism: a systematic review. Epilepsy & Behavior 98(Pt A):238–248, 2019. europepmc.org/article/MED/31398688
5. Mouridsen SE, Rich B, Isager T. A longitudinal study of epilepsy and other central nervous system diseases in individuals with and without a history of infantile autism. Brain & Development 33(5):361–366, 2011. europepmc.org/article/MED/20655678
6. Hand BN, Angell AM, Harris L, Carpenter LA. Prevalence of physical and mental health conditions in Medicare-enrolled, autistic older adults. Autism 24(3):755–764, 2020. europepmc.org/article/MED/31773968
7. Mouridsen SE, Rich B, Isager T. Epilepsy in individuals with a history of Asperger's syndrome: a Danish nationwide register-based cohort study. Journal of Autism and Developmental Disorders 43(6):1308–1313, 2013. europepmc.org/article/MED/23054204
8. Strasser L, Downes M, Kung J, Cross JH, De Haan M. Prevalence and risk factors for autism spectrum disorder in epilepsy: a systematic review and meta-analysis. Developmental Medicine & Child Neurology 60(1):19–29, 2018. europepmc.org/article/MED/29119560
9. Sundelin HE, Larsson H, Lichtenstein P, Almqvist C, Hultman CM, Tomson T, Ludvigsson JF. Autism and epilepsy: a population-based nationwide cohort study. Neurology 87(2):192–197, 2016. europepmc.org/article/MED/27306624
10. Scottish Intercollegiate Guidelines Network. Assessment, diagnosis and interventions for autism spectrum disorders (SIGN 145). SIGN, 2016. sign.ac.uk/media/1081/sign145.pdf
11. Bolton PF, Carcani-Rathwell I, Hutton J, Goode S, Howlin P, Rutter M. Epilepsy in autism: features and correlates. British Journal of Psychiatry 198(4):289–294, 2011. europepmc.org/article/MED/21972278
12. Amiet C, Gourfinkel-An I, Bouzamondo A, Tordjman S, Baulac M, Lechat P, Mottron L, Cohen D. Epilepsy in autism is associated with intellectual disability and gender: evidence from a meta-analysis. Biological Psychiatry 64(7):577–582, 2008. europepmc.org/article/MED/18565495
13. Woolfenden S, Sarkozy V, Ridley G, Coory M, Williams K. A systematic review of two outcomes in autism spectrum disorder – epilepsy and mortality. Developmental Medicine & Child Neurology 54(4):306–312, 2012. europepmc.org/article/MED/22348343
14. World Health Organization. ICD-10 Version 2019: F84.5 Asperger syndrome. WHO, 2019. icd.who.int/browse10/2019/en (F84.5)
15. Schendel DE, Overgaard M, Christensen J, Hjort L, Jørgensen M, Vestergaard M, Parner ET. Association of psychiatric and neurologic comorbidity with mortality among persons with autism spectrum disorder in a Danish population. JAMA Pediatrics 170(3):243–250, 2016. europepmc.org/article/MED/26752506
16. Scottish Intercollegiate Guidelines Network. Diagnosis and management of epilepsy in adults (SIGN 143, updated 2018). SIGN, 2015. sign.ac.uk/media/1079/sign143_2018.pdf
17. Harden C, Tomson T, Gloss D, et al. Practice guideline summary: sudden unexpected death in epilepsy incidence rates and risk factors. Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology and the American Epilepsy Society. Neurology 88(17):1674–1680, 2017. europepmc.org/article/MED/28438841
18. Sun JJ, Perera B, Henley W, et al. Epilepsy related multimorbidity, polypharmacy and risks in adults with intellectual disabilities: a national study. Journal of Neurology 269(5):2750–2760, 2022. europepmc.org/article/MED/35067759
19. Kiani R, Tyrer F, Jesu A, Bhaumik S, Gangavati S, Walker G, Kazmi S, Barrett M. Mortality from sudden unexpected death in epilepsy (SUDEP) in a cohort of adults with intellectual disability. Journal of Intellectual Disability Research 58(6):508–520, 2014. europepmc.org/article/MED/23647577
20. Shaw KA, McArthur D, Bilder DA, et al. Mortality among youth and young adults with autism spectrum disorder, intellectual disability, or cerebral palsy. JAMA Pediatrics 180(4):402–412, 2026. europepmc.org/article/MED/41661606
21. Kerr M, Linehan C, Thompson R, Mula M, Gil-Nagel A, Zuberi SM, Glynn M. A White Paper on the medical and social needs of people with epilepsy and intellectual disability: the Task Force on Intellectual Disabilities and Epilepsy of the International League Against Epilepsy. Epilepsia 55(12):1902–1906, 2014. europepmc.org/article/MED/25378101
22. Sun JJ, Watkins L, Henley W, et al. Mortality risk in adults with intellectual disabilities and epilepsy: an England and Wales case–control study. Journal of Neurology 270(7):3527–3536, 2023. europepmc.org/article/MED/37022478