Sleep Apnoea and Down Syndrome: The Most Under-Treated Problem in Australian Disability Support

Sleep apnoea and Down syndrome: the most under-treated problem in Australian disability support

If you work in disability support and you only ever read one clinical guide about Down syndrome, read this one.

Obstructive sleep apnoea is the most common serious medical condition in Down syndrome. It is more common than congenital heart disease. It is far more common than thyroid disease. In some published series the prevalence in adults approaches 100%. It damages cognition, mood, behaviour, blood pressure and the heart. It is diagnosable with one overnight test. It is treatable.

And in Australian disability services it is barely on the agenda. We have reviewed support plans for adults with Down syndrome that run to forty pages, cover mealtime management, continence, community access and behaviour in detail, and contain not one word about sleep.

This guide is an attempt to change that, for at least a few people.

The numbers, and why they are so much higher than you think

The literature here is unusually consistent in direction and unusually wide in range, and both facts are informative. The figures below are drawn principally from the review of obstructive sleep apnoea in Down syndrome published in Nature and Science of Sleep.

In children with Down syndrome, prevalence estimates run from roughly 50% to 100%, against about 1% to 5% of children generally. The spread reflects how the studies were done — who was selected, what threshold was used, whether the children were symptomatic.

In adults, estimates in some series approach 100%.

The most useful single study for our purposes is Maris and colleagues, who did polysomnography on more than 120 unselected patients — that is, not a clinic sample of children whose parents had complained about snoring, but everybody. 66% had obstructive sleep apnoea. About half of those cases were severe.

And then the figure that should change practice: among the children with no snoring and no witnessed apnoeas, 53% had obstructive sleep apnoea. Over half of the children whose families had noticed nothing had the condition.

A separate review of 144 polysomnography studies found 78% with OSA, a mean apnoea–hypopnoea index of 9.8, and 45% with moderate-to-severe disease. Around 22% had significant hypercapnia — carbon dioxide retention — which is a marker of a more serious respiratory picture than simple obstruction.

Hold those two things together. Two in three people with Down syndrome have obstructive sleep apnoea on objective testing. Half the people with no symptoms at all have it. Which means symptom-based screening — asking the family whether the person snores — is close to useless as a way of deciding who gets tested.

Why the airway fails

This is not one problem. It is five or six overlapping ones, which is why treatment in Down syndrome is harder than in the general population.

Anatomy. Midface hypoplasia means a smaller, flatter upper airway. Relative macroglossia means a large tongue in a small oral cavity. Adenotonsillar hypertrophy is common, and so is lingual tonsil hypertrophy — tonsil tissue at the base of the tongue, which standard tonsillectomy does not remove and which is easy to miss on examination. Nasal turbinates are often enlarged. The nasopharynx is narrow.

Muscle tone. Generalised hypotonia includes the pharyngeal dilator muscles that hold the airway open during sleep. This is probably the single biggest reason Down syndrome airways collapse, and it is also the reason they keep collapsing after surgery removes the obstructing tissue.

Comorbidities that make it worse. Obesity, which is substantially more common. Hypothyroidism, which is 10 to 30 times more common and which independently worsens sleep-disordered breathing. Gastro-oesophageal reflux. All three are treatable and all three are frequently untreated.

Central apnoea. Younger children with Down syndrome have a higher rate of central events — pauses driven by respiratory control rather than obstruction — probably reflecting both hypotonia and immature central control. This matters because central apnoea does not respond to the same treatments.

Multi-level obstruction. In drug-induced sleep endoscopy studies, obstruction was found at the tongue base in about 24% and epiglottic collapse in about 49%. That is to say, in a substantial proportion the problem is not where surgeons usually look.

One more finding worth knowing because it contradicts clinical intuition: tonsil size and BMI did not reliably predict who had obstructive sleep apnoea in some cohorts. A slim person with Down syndrome and small tonsils can have severe disease.

What untreated sleep apnoea does

This is the part that matters for anybody writing a support plan.

Cognition. In one study of 38 children with Down syndrome, those with obstructive sleep apnoea had verbal IQ scores around nine points lower than those without. Nine points of verbal IQ, in a population where verbal short-term memory is already the specific weak point, is a very large amount of function to lose to a treatable condition. Adults with Down syndrome and OSA also show worse cognitive outcomes.

Behaviour. Daytime sleepiness, irritability, poor concentration, reduced frustration tolerance. In a person with limited expressive language, chronic sleep deprivation presents almost exclusively as behaviour. This is why we keep saying: rule out sleep apnoea before you write a behaviour support plan.

The heart and lungs. Up to 56% of people with Down syndrome have congenital heart disease, which already raises pulmonary hypertension risk. Obstructive sleep apnoea worsens pulmonary hypertension, and treating the apnoea can improve it. In someone with a repaired cardiac defect and untreated OSA, that is a genuinely dangerous combination.

Possibly dementia risk. This one is not settled, so we will put it carefully. Sleep-disordered breathing is associated with cognitive decline in the general population, people with Down syndrome have an extremely high baseline risk of early Alzheimer’s disease, and an untreated condition that chronically disrupts sleep architecture and causes intermittent hypoxia in that population is at minimum worth taking seriously. What is beyond dispute is that untreated OSA produces cognitive and functional decline that looks like dementia and is reversible, which means it has to be excluded before a dementia diagnosis is made in an adult with Down syndrome. The Global Down Syndrome Foundation guidelines list sleep apnoea among the conditions to rule out first.

Testing: what to ask for and when

The American Academy of Pediatrics has recommended since 2011 that every child with Down syndrome have a polysomnogram by age 4, regardless of symptoms.

Australian practice does not reliably follow this. A great many Australian children with Down syndrome reach school age without a sleep study, and a great many Australian adults have never had one. If you are a parent reading this and your child has not had one, that is the question for your next paediatric appointment.

Full polysomnography is the diagnostic standard, and the alternatives are weaker than people assume. Overnight oximetry and capnography have poor sensitivity in this population — a normal oximetry trace does not rule out significant disease. The American Academy of Sleep Medicine recommends full polysomnography over cardiorespiratory polygraphy. If you are offered a home oximetry study as a substitute, it is reasonable to ask whether a full study is available, and to accept the oximetry as a screening step rather than a conclusion.

For adults, there is no equivalent guideline setting an age. The sensible position given prevalence approaching 100% in some series is a very low threshold: any adult with Down syndrome who has daytime sleepiness, snoring, witnessed pauses, morning headaches, unexplained weight gain, treatment-resistant hypertension, worsening behaviour, or any unexplained functional decline should have a sleep study. In practice that is most adults with Down syndrome at some point.

Getting a sleep study in Australia

Paediatric polysomnography is available through public children’s hospitals in each state, usually with a wait, and privately with a referral and a gap payment. Adult sleep studies are more widely available. A GP can refer; for a person with Down syndrome, a respiratory or sleep physician referral is usually better because of the multi-level obstruction and the central apnoea possibility.

The practical barrier is rarely the referral. It is the night itself. A sleep study means an unfamiliar room, electrodes glued to the scalp, a nasal cannula, bands around the chest and abdomen, and a technician coming in during the night. For a person with Down syndrome and limited communication, that is a lot.

Things that genuinely help: ask whether a parent or familiar support worker can stay overnight, which most paediatric and many adult labs allow. Ask for photographs of the room and the equipment in advance, and build a social story. Request that the leads be applied slowly with explanation rather than efficiently. Bring the person’s own pillow and bedding. Ask whether a daytime desensitisation visit is possible first. Some labs are very good at this and some have never been asked; asking changes the night.

Where the NDIS comes in: the support worker’s time to attend the study overnight is legitimate plan content, and so is the preparation work. A sleep study that fails because nobody prepared the person is a wasted public hospital bed and a six-month wait repeated.

Treatment, and realistic expectations

This is where Down syndrome diverges most sharply from general practice, and where families are most often given a falsely optimistic picture.

Adenotonsillectomy

In otherwise healthy children without Down syndrome, removing the tonsils and adenoids cures obstructive sleep apnoea in up to about 80% of cases.

In Down syndrome, 50% to 75% have clinically significant residual disease after surgery. The average reduction in apnoea–hypopnoea index is around 50%.

That is a genuinely different number and it has two implications. First, surgery is still usually worth doing — halving the AHI is a real benefit. Second, a post-operative sleep study is essential, and it is frequently not done. A child who has had their tonsils out and is still tired, still irritable and still not progressing may well still have moderate disease. If nobody re-tests, everybody assumes the problem was dealt with.

On safety: complication rates are broadly similar to the general population, with some excess bleeding risk — one cohort reported post-operative haemorrhage in 2.8% of children with Down syndrome against 1.2% of controls, and one review found 10% late-onset haemorrhage. The recommendation is referral to a centre experienced with medically complex patients, which in Australia means a tertiary paediatric centre rather than a day surgery.

CPAP

Continuous positive airway pressure works. The problem is wearing it.

The adherence data in Down syndrome is more encouraging than the folklore suggests but still sobering. In a randomised trial of 28 adults, average nightly use was about three hours, and roughly two-thirds were still using it at 12 months. A separate smaller study of 11 people found 81% using CPAP more than four hours a night one to three years after starting.

Read those two studies together and the message is: CPAP adherence in Down syndrome is achievable, it varies enormously, and the variance is almost certainly about the quality of the support around it rather than anything intrinsic.

What makes the difference, in our experience and consistent with the literature:

Mask fitting is not a five-minute job. Facial anatomy in Down syndrome — flatter midface, smaller nasal bridge — makes standard masks leak. A mask that leaks wakes the person, and a person woken by their mask takes it off. Getting this right can take several appointments with a good CPAP therapist and it is the highest-return investment in the whole process.

Desensitisation, not compliance. Start with the mask off the machine, held near the face for thirty seconds while watching television. Build up over weeks. The failures we see almost all involve a machine delivered on a Friday with an instruction to wear it that night.

The support team has to be trained and consistent. In a supported independent living house with rotating staff, CPAP succeeds or fails on whether every worker on the evening shift does the same thing in the same order. This belongs in the support plan with the same specificity as a mealtime management plan: who sets it up, what pressure, what to do if the person removes it at 2am, when to record non-use, who to tell.

Somebody has to read the machine data. Modern CPAP units record hours of use, leak and residual AHI. That data is the only objective measure of whether the treatment is working, and in disability settings it is very often not downloaded for months.

Everything else

Intranasal corticosteroids and montelukast have evidence mainly in children without Down syndrome, and are a reasonable adjunct for mild disease or residual disease after surgery.

Treating the comorbidities is the cheapest intervention on the list. Correct hypothyroidism. Manage reflux. Address weight, with a dietitian who understands that resting metabolic rate is lower in Down syndrome and generic calorie advice underperforms.

Rapid maxillary expansion — orthodontic widening of the upper jaw — has a role in selected children.

Advanced surgery guided by drug-induced sleep endoscopy, such as tongue base reduction or lingual tonsillectomy, targets the obstruction sites standard tonsillectomy misses. Given that tongue base obstruction was found in about a quarter and epiglottic collapse in about half in DISE studies, this is the right approach for persistent disease after adenotonsillectomy.

Hypoglossal nerve stimulation is the newest option and the results in Down syndrome are striking: in adolescents with Down syndrome, AHI fell 56% to 85% at six to twelve months. It is an implanted device that stimulates the nerve controlling tongue position during sleep. Availability in Australia is limited and it is not a first-line option, but for a young person with severe residual disease and failed CPAP it is worth asking a sleep physician about.

Positional therapy and sleep hygiene are supportive rather than curative, and worth doing anyway. Some people with Down syndrome have markedly worse apnoea supine.

Oropharyngeal exercises — myofunctional therapy — have not been studied in children with Down syndrome. Reasonable to try, no evidence base to cite.

What this means for a support plan

Concretely, if you are writing or reviewing a plan for a person with Down syndrome:

Record whether a sleep study has ever been done, and when. If the answer is no or more than five years ago, that is an action item.

If the person uses CPAP, the plan needs a CPAP protocol with the same detail as any other clinical support: setup steps, pressure settings, mask type and size, cleaning schedule, what to do on removal, how non-use is recorded, who reviews the machine data and how often, and when to escalate.

Record daytime sleepiness as a measurement, not an impression. “Fell asleep in the van on the way to program on 11 of 14 trips” is data. “Seems tired” is not.

Before any behaviour support referral, document that sleep apnoea has been excluded — along with thyroid function, pain, hearing and vision. This should be a standing item, and in a well-run service it is a box on the referral form.

If the person is over 40 and declining, exclude sleep apnoea before anybody says dementia. See Alzheimer’s disease and Down syndrome for the full differential, and the health screening schedule for how sleep fits into the broader surveillance picture.

Nine points of verbal IQ. Half of asymptomatic people affected. One overnight test. The arithmetic here is not difficult, and the gap between what the evidence says and what Australian disability services actually do is the largest we know of in Down syndrome care.