Seizures occur in autistic individuals at far higher rates than in the general population, with roughly one in ten autistic people developing epilepsy over their lifetime. The seizures themselves look the same as they do in anyone else, but recognizing them can be harder when a person already has behavioral differences, communication challenges, or sensory sensitivities that overlap with how seizures sometimes present. Understanding which signs to watch for, when seizures tend to emerge, and what puts an autistic person at higher risk matters for getting timely treatment and avoiding complications that can worsen both conditions.
How Common Are Seizures in Autism
Estimates of epilepsy among autistic people have varied widely depending on the study population, but a large systematic review and meta-analysis put the overall prevalence at about one in ten.1PubMed. Prevalence of epilepsy in autism spectrum disorders: A systematic review and meta-analysis That figure is roughly five to ten times higher than in the general population. Rates climbed higher in certain subgroups: adolescents, adults, females, and those with intellectual disability were all more likely to have epilepsy alongside autism. Conversely, autism is also overrepresented among people who have epilepsy, with estimates of about 20% of epilepsy patients meeting criteria for autism.2PubMed Central. Epilepsy in patients with autism: links, risks and treatment challenges The overlap runs in both directions, which tells researchers these are not two entirely separate conditions that just happen to show up together.
The numbers have shifted as diagnostic criteria for autism have broadened. Because more people with milder presentations now receive an autism diagnosis, the percentage who also have epilepsy has probably drifted downward in recent studies compared to older estimates that drew from more severely affected clinical populations.3PubMed Central. Epilepsy in patients with autism: links, risks and treatment challenges When reading any prevalence figure, it is worth keeping in mind how the sample was defined.
What Seizures Actually Look Like in Autistic People
There is no single seizure type that goes hand in hand with autism. The full range of epilepsy syndromes has been documented, though focal seizures, which start in one area of the brain, tend to be the most commonly reported.4PubMed. Clinical characteristics of children and young adults with co-occurring autism spectrum disorder and epilepsy In one study of 74 autistic patients with epilepsy, focal epilepsies accounted for about 58% of cases, generalized epilepsies for roughly a quarter, and epileptic encephalopathies for about 11%.5PubMed. Focus on epilepsy and epilepsy syndromes in children with autism spectrum disorders: a study of 74 patients
In practical terms, the signs a parent or caregiver might see include:
- Staring spells: The person appears to “zone out” for seconds at a time, sometimes with subtle eye blinking or lip smacking. These absence seizures can be mistaken for the inattention or self-absorption that is already part of the autism profile.
- Convulsions: Tonic-clonic (formerly called grand mal) seizures involve stiffening followed by rhythmic jerking of the limbs. These are usually unmistakable, but in younger children they can be confused with intense tantrums if the jerking phase is brief.
- Myoclonic jerks: Sudden, brief muscle twitches of the arms, shoulders, or whole body. They can look like a startle response.
- Focal aware seizures: The person stays conscious but experiences involuntary movements on one side of the body, unusual sensations, or sudden emotional changes like unexplained fear. Because many autistic individuals already have atypical emotional responses, these episodes can go unrecognized.
- Drops or falls: Atonic seizures cause a sudden loss of muscle tone, leading to collapses. In a child who already has motor clumsiness, a caregiver may chalk these up to coordination problems.
The challenge is that many of these presentations overlap with behaviors commonly associated with autism itself. Repetitive movements could be stimming or could be seizure activity. A sudden behavioral arrest could be a sensory overload moment or an absence seizure. If you notice episodes that are brief, stereotyped (always look the same), occur in clusters, or are followed by confusion or drowsiness, those features point more toward seizures than toward typical autism-related behavior.
Why Do Autism and Seizures Co-Occur So Often
The two conditions share biological roots. At the cellular level, both preclinical and clinical research points to a disturbance in the balance between excitatory and inhibitory signaling in the brain. When the brain’s excitatory circuits fire too easily or its inhibitory circuits cannot keep pace, the threshold for seizures drops, and the same imbalance appears to disrupt the neural circuits involved in social cognition, language, and sensory processing.6PubMed. Neurobiological bases of autism-epilepsy comorbidity: a focus on excitation/inhibition imbalance This excitatory-inhibitory imbalance is not caused by one gene or one brain region. It can emerge from mutations affecting synaptic channels, from disruptions in how neurons form connections during development, or from abnormalities in the molecules that regulate gene activity in the brain.7PubMed Central. Shared Etiology in Autism Spectrum Disorder and Epilepsy with Functional Disability
There is also evidence that neuroinflammation plays a role. A review of studies examining brain tissue and imaging found consistent signs of activated immune cells in the brain (microglia) across multiple brain regions in autistic individuals, with changes in both cell number and cell shape pointing to ongoing inflammatory processes.8PubMed Central. Microglia mediated neuroinflammation in autism spectrum disorder Neuroinflammation can lower the seizure threshold further, creating a feedback loop where inflammation promotes seizures and seizures promote more inflammation.
Brain imaging adds another layer. Abnormal gray and white matter volumes appear to be present before the onset of autism symptoms and at the time epilepsy begins, suggesting these structural differences are not just consequences of either condition but precursors to both.9PubMed. Structural MRI biomarkers of shared pathogenesis in autism spectrum disorder and epilepsy Atypical brain growth trajectories, including blunted gray and white matter maturation, are common across both disorders.
Who Is at Higher Risk
Not every autistic person will develop seizures. The single strongest predictor identified in the research is intellectual disability. A systematic review found that a lower cognitive level or the presence of intellectual disability was associated with a higher occurrence of epilepsy in 12 out of 13 studies that examined the question, including all four studies rated as good quality.10PubMed Central. Factor associated with the occurrence of epilepsy in autism: a systematic review This means an autistic individual with average or above-average cognitive abilities has a meaningfully lower seizure risk than someone with co-occurring intellectual disability, though the risk is still elevated compared to the general population.
Age is another factor. Seizures in autism tend to peak at two different windows: early childhood and adolescence. The adolescent peak is thought to be driven partly by hormonal changes and ongoing brain maturation, and it catches some families off guard when a teenager who never had seizures as a young child begins having them. Female sex is also associated with higher rates, as noted in the meta-analytic data. Certain genetic conditions that feature both autism and epilepsy, such as Dravet syndrome and duplications of chromosome 15, carry particularly high seizure burdens.
Epileptiform Activity Without Obvious Seizures
A complicating feature of the autism-epilepsy overlap is that many autistic individuals show abnormal electrical activity on an EEG (electroencephalogram) even when they have never had a recognized seizure. Rates of these “epileptiform discharges” have been reported as high as 60% in some studies of autistic children.11PubMed Central. The role of epilepsy and epileptiform EEGs in autism spectrum disorders Some researchers have proposed that this subclinical electrical activity could itself contribute to the cognitive and behavioral features of autism, though this remains debated.
A study of 151 autistic children who underwent overnight EEG found that about 17% went on to develop unprovoked seizures. Children whose initial EEGs showed epileptiform discharges had roughly four times the risk of developing seizures later, and those with background slowing on EEG had about three times the risk.12PubMed. Overnight Electroencephalogram to Forecast Epilepsy Development in Children with Autism Spectrum Disorders This makes overnight EEG a potentially useful screening tool for identifying which autistic children are most likely to develop epilepsy, even before any clinical seizure has occurred. Sleep EEGs are generally preferred for this purpose because epileptiform activity is more likely to show up during sleep.
Regression, Seizures, and the Chicken-or-Egg Question
Some autistic children experience a period of regression, losing language, social skills, or other abilities they had previously acquired, typically between 15 and 24 months of age. When seizures or epileptiform activity are present around the same time, families and clinicians naturally wonder whether the seizures caused the regression. The relationship is genuinely murky. In one study examining children with pervasive developmental disorders, regression occurred at similar rates among children with and without epilepsy, suggesting that seizures are not the sole driver of skill loss.13Pediatrics. Regression in Pervasive Developmental Disorders: Seizures and Epileptiform Electroencephalogram Correlates
That said, certain epileptic encephalopathies can cause severe regression. In conditions like epilepsy with continuous spike-and-wave during sleep (sometimes called ESES or CSWS), the constant abnormal electrical activity during sleep actively disrupts brain development and can produce dramatic losses in language and cognition.14PubMed Central. Autism and epilepsy: what has regression got to do with it? These are relatively rare situations, but they are important to catch because treating the seizure activity aggressively can sometimes halt or partially reverse the regression. If your child has lost skills and you have not explored whether subclinical seizures might be playing a role, it is worth discussing an EEG with their neurologist.
The Sleep Connection
Sleep problems are strikingly common in autism. Difficulty falling asleep, frequent night wakings, and shortened total sleep time affect a large proportion of autistic children and adults. This creates a problematic interaction with seizures, because sleep deprivation is one of the most reliable triggers for seizure activity, and seizures in turn can fragment sleep architecture, setting up a vicious cycle.15PubMed. Sleep disorders, epilepsy, and autism Addressing sleep problems in an autistic person who also has seizures is not just about comfort or daytime functioning. It can directly improve seizure control. Sleep hygiene measures, melatonin supplementation (which has a reasonably good evidence base in autism), and behavioral sleep interventions are all worth trying alongside seizure-specific treatment.
Nocturnal seizures add another layer of difficulty. A seizure that happens during sleep may go completely unwitnessed, and the only clue the next morning might be unexplained fatigue, bed-wetting in a child who had been dry, a bitten tongue, or unusual irritability. In nonverbal autistic individuals, these clues are easy to miss or attribute to other causes.
When Brain Imaging Helps
Brain MRI is not routine for every autistic person, but it becomes more informative when seizures are part of the picture. A review of MRI studies found that among autistic children referred for imaging, the prevalence of definite brain abnormalities was about 22% in those with seizures, compared to only about 7% in those referred for autism alone.16PubMed. The Implications of Brain MRI in Autism Spectrum Disorder The types of abnormalities found can include cortical malformations, white matter abnormalities, and other structural changes that may point toward a specific underlying cause. In a separate study of autistic children undergoing MRI, epilepsy was the second most common reason for referral after developmental delay.17PubMed Central. Yield of brain MRI in children with autism spectrum disorder The takeaway for families is that if an autistic person develops seizures, an MRI is generally a reasonable next step and occasionally reveals something actionable.
Treatment Challenges
Treating seizures in autistic individuals follows the same general principles as treating epilepsy in anyone else, but with some important wrinkles. Despite the strong association between the two conditions, there is remarkably little high-quality evidence specifically addressing which anti-seizure medications work best in this population. A pharmacotherapy review noted that no Level 1 evidence (from well-designed randomized controlled trials) or national treatment guidelines exist specifically for epilepsy in autism.18PubMed. A review of the pharmacotherapeutic considerations for managing epilepsy in people with autism In practice, clinicians draw on the broader epilepsy treatment literature and then tailor their approach based on the individual’s seizure type, EEG findings, and tolerance of side effects.
Side effects are a particular concern. Many anti-seizure medications can affect mood, cognition, and behavior. In someone who already has challenges in these domains, a drug that causes drowsiness, irritability, or cognitive slowing may worsen quality of life even as it controls seizures. The general recommendation is to start at low doses and increase slowly, paying close attention to behavioral changes.19PubMed. A review of the pharmacotherapeutic considerations for managing epilepsy in people with autism Communication barriers make this monitoring harder. A verbal adult can tell you that a new medication is making them feel foggy or sad. A nonverbal child cannot, so caregivers need to track behavior systematically and report changes proactively.
For drug-resistant cases, where seizures persist despite trials of two or more appropriate medications, there are additional options. Vagus nerve stimulation, which involves a small implanted device that sends electrical pulses to the brain via a nerve in the neck, has been used for refractory epilepsy and may also improve some autism-associated symptoms. Deep brain stimulation is another option in severe cases. Dietary approaches, particularly the ketogenic diet and its variants, have shown benefit for seizure control in some individuals and are sometimes considered when medications are not enough.20Neural Regeneration Research. Autism spectrum disorder comorbid with epilepsy: Etiology, mechanism, and therapy
Cannabis-Based Treatments
Interest in cannabidiol (CBD) and cannabis-based treatments has surged among autism families, driven partly by its approval for certain severe epilepsy syndromes. In an observational study of autistic patients treated with cannabis oil (predominantly CBD with low THC), seizure symptoms were reported to have disappeared in the majority of those who had seizures at baseline, with the remainder reporting improvement. Side effects were mostly mild, with restlessness being the most commonly reported.21Scientific Reports. Real life Experience of Medical Cannabis Treatment in Autism: Analysis of Safety and Efficacy A separate randomized, double-blind, placebo-controlled trial of a CBD-rich cannabis extract in autistic children found improvements in social interaction, anxiety, and psychomotor agitation compared to placebo, with adverse effects reported in about 10% of the treatment group.22Trends in Psychiatry and Psychotherapy. Evaluation of the efficacy and safety of cannabidiol-rich cannabis extract in children with autism spectrum disorder: randomized, double-blind, and placebo-controlled clinical trial
These results are promising but should be interpreted carefully. The observational study lacked a control group, and the randomized trial was relatively small. CBD can also interact with anti-seizure medications, sometimes raising blood levels of drugs like clobazam or valproate. Anyone considering CBD or cannabis-derived products for an autistic person with seizures should work with a neurologist who can monitor drug levels and adjust dosing accordingly.
Mortality and Long-Term Outlook
The combination of autism and epilepsy carries higher stakes than either condition alone. A systematic review estimated that autistic individuals have a standardized mortality ratio of roughly 2.8, meaning they die at nearly three times the rate expected for the general population after adjusting for age and sex.23PubMed. A systematic review of two outcomes in autism spectrum disorder – epilepsy and mortality Epilepsy is one of the leading contributors to this excess mortality. Sudden unexpected death in epilepsy (SUDEP), a rare but devastating event in which a person with epilepsy dies without a clear structural or toxicological cause, is a particular concern. A review of SUDEP genetics found that Dravet syndrome and autism with chromosome 15 duplication together accounted for about a fifth of cases where an antemortem diagnosis was recorded.24PubMed Central. Systematic Review of the Genetics of Sudden Unexpected Death in Epilepsy: Potential Overlap With Sudden Cardiac Death and Arrhythmia-Related Genes
These numbers are not meant to frighten but to underscore why seizures in autistic individuals deserve serious clinical attention. Good seizure control, attention to sleep safety (avoiding prone sleeping positions during seizures, using seizure monitors if appropriate), and regular neurology follow-up can all reduce risk. For families who have been told that brief or infrequent seizures in their autistic child are “not a big deal,” these long-term data suggest otherwise.
Practical Steps for Families and Caregivers
Because seizures can present subtly in autistic individuals, maintaining a high index of suspicion is important. Keep a log of any episodes that look unusual or stereotyped, and try to capture them on video if possible. Video is enormously helpful for neurologists trying to distinguish seizure activity from behavioral events. Note what the person was doing before the episode, how long it lasted, whether one side of the body was affected more than the other, and how the person acted afterward. Post-seizure confusion, sleepiness, or temporary worsening of communication are common after epileptic events and less typical after behavioral ones.
If an autistic person has never had a seizure but has risk factors (intellectual disability, a known genetic syndrome associated with epilepsy, a history of regression), asking about an overnight EEG is reasonable. Abnormal findings on that test do not guarantee seizures will happen, but they can guide monitoring and sometimes prompt earlier intervention. For those already on anti-seizure medication, the key is maintaining close communication with the prescribing neurologist about behavioral side effects, since the person with autism may not be able to articulate what the medication is doing to their mood or thinking. Caregivers who track behavior changes carefully and advocate based on those observations fill a gap that the clinical system is not always set up to address on its own.