Epilepsy and Intellectual Disability: An Australian Guide

Epilepsy and intellectual disability: one in four, and the hardest to diagnose

Roughly one in four people with a cognitive disability in Australia also has epilepsy. In cerebral palsy with intellectual disability the figure is around 48 per cent. Among adults with Down syndrome over 50, it is about 45 per cent.

Those figures come from the Epilepsy Foundation’s own Australian guidance, and they explain why a disability provider writes about epilepsy at all. For a service supporting adults with intellectual disability, epilepsy is not an occasional complication. It is something close to a quarter of the people you support have, and it is the version of epilepsy that is hardest to diagnose, hardest to control, and carries the highest risk of preventable death.

The Epilepsy Foundation’s guidance is direct about that last point: people with epilepsy and a cognitive disability tend to have more severe, difficult-to-control seizures and a higher risk of preventable death, with a worse prognosis, lower rates of seizure freedom, more frequent use of multiple anti-seizure medications, and high rates of illness and death including SUDEP. It also notes something families say constantly — that the effect on the person and their family is often greater than the seizures themselves.

This guide covers why the diagnosis is so difficult, the specific syndromes involved, the medication problems, the mental health that gets missed, and what good support actually looks like. The operational detail of supporting somebody — management plans, emergency medication, recording, overnight arrangements and worker competency — is in epilepsy and seizure support.

The numbers

The pattern in that table is the important part: the rate rises with the degree of disability. Epilepsy and intellectual disability frequently share a cause — a brain that developed differently, or was injured, produces both — which is why they travel together, and why the more significant the disability the more likely epilepsy is to accompany it.

And the Down syndrome figures deserve separate attention, because the jump from 5 to 10 per cent in childhood to around 45 per cent in adults over 50 reflects late-onset seizures associated with Alzheimer’s disease, which affects people with Down syndrome far earlier than the general population. New seizures in an adult with Down syndrome are a specific clinical event requiring assessment, not an expected part of ageing. See Alzheimer’s disease and Down syndrome.

For cerebral palsy, see understanding cerebral palsy — epilepsy is one of the commonest associated conditions and its presence changes what support is needed.

Why diagnosis is so much harder

The Epilepsy Foundation sets out the reasons, and each one has a practical answer.

The person may not be able to describe what they experience. A focal aware seizure — the rising sensation, the odd smell, the wave of fear — is entirely internal. Somebody who cannot report it has seizures nobody knows about. This is why, for people with limited communication, observation is the diagnostic instrument, and why the people who spend the most time with somebody are the people holding the most important data.

Stereotyped mannerisms can be mistaken for seizure movements. Hand flapping, rocking, repetitive vocalising and self-stimulatory behaviour look like seizure activity to somebody who does not know the person, and they get recorded as seizures. The result is over-diagnosis and unnecessary medication.

Behaviour linked to pain or frustration can obscure seizure activity. The reverse error — a genuine seizure recorded as a behavioural incident.

Some people cannot tolerate EEG or MRI. This is a real and under-acknowledged barrier. Sedation or general anaesthetic may be needed, which raises the threshold for ordering a test and means fewer tests get done. Desensitisation work by an occupational therapist or a specialist nurse before the appointment genuinely improves this, and it can be funded.

And diagnostic overshadowing, which is the central problem. Physical or behavioural changes get attributed to the disability rather than investigated as seizures. The Epilepsy Foundation describes exactly this: changes assumed to come from the disability, leading to misdiagnosis.

Misdiagnosis runs in both directions, which the guidance states plainly: non-epileptic events labelled as epilepsy, and epileptic seizures missed or untreated. Both happen, and both cause harm — unnecessary medication with real side effects on one side, untreated seizures with real risk on the other.

The three questions that help most, from the same guidance. Epilepsy is more likely if the symptoms:

Differ from the person’s usual pattern. This is the single most useful discriminator and it is why knowing somebody well matters clinically.

Occur during sleep.

Last longer than usual.

What closes the gap: observation records from family and support workers. Dated, timed, described in plain observable terms, with video where there is consent. The Epilepsy Foundation names these as helping specialists, and in practice they frequently are the diagnosis — a neurologist seeing somebody for twenty minutes cannot know what their baseline looks like.

The syndromes that come with intellectual disability

A group of severe epilepsies cause intellectual disability as well as seizures, and three are worth knowing by name because two of them appear on the NDIS access lists.

Lennox-Gastaut syndrome. Multiple seizure types — tonic, atonic, atypical absence — with a characteristic EEG pattern and intellectual disability. The atonic drop attacks are the feature that does most harm, because they come without warning and cause facial and dental injury. Highly drug-resistant. Named on NDIS List B.

Infantile epileptic spasms syndrome (formerly West syndrome). Clusters of spasms in infancy, a characteristic EEG, and developmental consequences. Treatment delay affects outcome, which makes it an urgent diagnosis — and the spasms are frequently mistaken for colic or startle. Named on NDIS List B as West’s syndrome.

Dravet syndrome. A genetic epilepsy, usually from an SCN1A variant, beginning with prolonged febrile seizures in infancy, followed by multiple seizure types, intellectual disability and gait problems. Highly drug-resistant. Specific medications must be avoided because they worsen seizures in Dravet, which is one of the clearest examples of why genetic diagnosis changes treatment — and cannabidiol and the ketogenic diet both have evidence here.

These are collectively called developmental and epileptic encephalopathies, meaning the seizures and the developmental impact both arise from the underlying brain condition, and the seizures themselves contribute further.

Why this matters for the NDIS: epilepsy itself is not named on the access lists, but Lennox-Gastaut syndrome and West’s syndrome are. If either applies, say so and attach the diagnosis. See epilepsy and the NDIS.

And ask for genetic testing if it has never been done in somebody with early-onset severe epilepsy and intellectual disability. Testing has improved substantially, a diagnosis sometimes changes medication, and many adults in the disability system were never tested because the technology did not exist when they were children.

Medication, which is more complicated here

Polytherapy is the norm and it is a problem. The Epilepsy Foundation notes more frequent use of multiple anti-seizure medications in this group. Each drug adds side effects, interactions and sedation, and the cumulative effect on alertness, mood, balance and cognition can be substantial — in somebody who may not be able to report it.

Side effects get read as the disability. Tiredness, poor concentration and mood changes are all recognised medication effects, and in somebody with intellectual disability they get attributed to the person rather than the drug. The Epilepsy Foundation flags exactly this. If somebody became more withdrawn, more irritable, less steady or less engaged after a medication change, suspect the medication and report it.

Some psychotropic medications lower the seizure threshold. Certain antidepressants and antipsychotics can do this — which matters enormously in a population where both are commonly prescribed, sometimes for behaviour. If somebody’s seizures worsened after a psychotropic medication started, that connection needs raising.

And the absolute rule, in the Epilepsy Foundation’s own words: “Under no circumstances should an ASM dosage be altered without specialist advice.”

The restrictive practice question, which is specific to disability services and needs getting right. Medication given to manage behaviour rather than to treat a diagnosed condition is chemical restraint and triggers the full framework — a behaviour support plan written by an NDIS behaviour support practitioner, state authorisation, monthly reporting to the NDIS Quality and Safeguards Commission, and a reduction strategy. Anti-seizure medications prescribed to treat epilepsy are not chemical restraint. But several of these drugs are also used for mood and behaviour, and some people are on both. The only way this works properly is for the prescriber to document the clinical indication for each medication explicitly, rather than leaving a provider to infer it. Ask for that in writing. The framework is set out in behaviour support and restrictive practices.

Adherence, swallowing and formulation. Liquid formulations, dispersible tablets, timing around meals and PEG administration all matter, and a pharmacist review is worth asking for. Never crush anything without checking.

The mental health nobody looks for

The Epilepsy Foundation cites around 50 per cent of people with epilepsy experiencing depression and about 20 per cent anxiety — and then makes the point that matters here: depression and anxiety can be missed in people with a cognitive disability because they may not express feelings clearly or show typical symptoms.

What depression looks like instead, in somebody with limited communication: withdrawal, loss of interest in things they liked, changes in sleep or appetite, increased irritability or aggression, new self-injury, slowed movement, more frequent seizures, or simply becoming harder to engage.

And the consequence the guidance names: mental health difficulties can reduce a person’s willingness to take medication — which worsens seizure control, which worsens everything.

So the instruction is to look for it actively rather than waiting for somebody to report it, and to raise behaviour change as a possible mood problem rather than only as a behaviour problem. See mental health and memory in epilepsy.

SUDEP, which concentrates here

The Epilepsy Foundation states that SUDEP occurs more often in people with an intellectual disability. That is unsurprising given the risk profile — more tonic-clonic seizures, more nocturnal seizures, drug-resistant epilepsy, long duration, and frequently limited ability to summon help.

Several risk factors are modifiable, and for people in supported living, two of them are organisational rather than clinical: medication adherence, and whether somebody is alone and unmonitored at night.

This is covered properly in SUDEP, and the night-time arrangements in a supported living context are covered in epilepsy and seizure support. The point to make here is that it should be a documented, discussed decision rather than a default — and that families of people with intellectual disability are, in our experience, even less likely to have had the conversation than families generally.

What good support looks like

The Epilepsy Foundation’s recommendations, which are specific and worth following.

A person-centred approach. Involve the person in all decisions, taking account of their life story, values, communication needs and goals. Not about them, with them.

An Epilepsy Management Plan (EMP), describing seizure types, triggers, first aid and post-seizure needs — developed with the doctor, the person and their supporters, and reviewed annually.

An Emergency Medication Management Plan (EMMP) where emergency medication is prescribed, authorising trained people to give it and stating when to call 000. Reviewed annually.

Records. Seizure diaries or apps, and video of seizures with the person’s consent.

A Wellbeing Map, to help the person prepare for specialist appointments.

Longer consultations, booked deliberately so questions can actually be asked. This is a legitimate request and it changes appointments entirely.

Consent and capacity handled properly. Adults are presumed able to consent. Use plain language. Consider a capacity assessment or guardianship only where there are genuine welfare concerns — not as a default.

Safety assessed at home and in the community, with options including personal alarms, shower chairs, firm pillows, and never swimming alone.

Training for carers and support workers in epilepsy management, seizure first aid and emergency medication where prescribed.

And carer wellbeing, which the guidance names explicitly.

Plus three of our own:

Get genetic testing if it has never been done in early-onset severe epilepsy.

Get a neurologist who will see this person properly — ideally one with experience in epilepsy and intellectual disability, because the assessment skills are different and the default is to under-investigate.

And protect staff continuity. For somebody whose seizures are identified by deviation from their usual pattern, a worker who knows the baseline is a clinical asset. High turnover is a safety issue in this population, not just a quality one.

Free help, and the numbers

The National Epilepsy Support Service, 1300 761 487, run by the Epilepsy Foundation, which produced the Australian guidance this article draws on, including a Learning about Epilepsy easy English booklet and a positive practice framework.

Epilepsy Action Australia, on 1300 37 45 37, with epilepsy nurse telehealth appointments available.

Both are free. Both will talk to families and to support workers, not only to the person with epilepsy.

The transition from paediatric to adult services

A specific failure point in this population, and one families are rarely warned about.

Children with severe epilepsy and intellectual disability are frequently managed by a paediatric neurology team that holds everything — seizures, medication, development, school, family support — in one place, with a consultant who has known the child for fifteen years and recognises their baseline without being told.

Then they turn eighteen, and that stops.

What goes wrong:

Nobody holds the baseline any more. In a population where epilepsy is identified largely by deviation from a person’s usual pattern, losing the clinician who knew that pattern is a clinical loss, not just an administrative one.

Adult neurology is not set up for it. General adult neurology clinics are busy, appointments are short, and the assessment skills needed for somebody with limited communication are different. People with intellectual disability and epilepsy are systematically under-investigated in adult services.

Medication stops being reviewed. A regimen settled at fourteen can run unchanged into a person’s thirties, including drugs that were added during a crisis and never removed. Polytherapy accumulated over years is common, and nobody is auditing it.

And the easy-English and family-inclusive practice that paediatric services do well frequently does not transfer.

What to arrange, starting at about sixteen:

Ask for a written transition plan naming the receiving adult neurologist individually, not just a department.

Ask specifically for a neurologist with experience in epilepsy and intellectual disability. They exist, they are concentrated in a small number of services, and asking by name gets a different answer than accepting the default allocation.

Get a GP to hold the whole picture, with a long appointment and the two-page summary described above.

Ask for a full medication review at transition, with the explicit question: is every one of these drugs still indicated, and what is the clinical indication for each? This is the single highest-value request on the list.

Transfer the Epilepsy Management Plan and the Emergency Medication Management Plan, and get them re-signed by the adult team rather than carried over unsigned.

Make sure the new team gets the observation records, the videos and the seizure history, not just a discharge letter.

And ask for genetic testing if it has never been done, because many adults in the disability system were children before the technology existed.