Several medical or psychiatric conditions occur alongside autism. These are called co-occurring conditions. Nearly three-quarters of autistic children are diagnosed with a co-occurring condition.

Co-occurring conditions can appear at any time during a child’s development. Some might not appear until later in adolescence or adulthood. Sometimes these conditions affect how autism therapies and supports help your child. That’s why it’s important to identify and diagnose the conditions and manage them separately.

Here are common co-occurring conditions that might be diagnosed in autistic children.

Anxiety

People with anxiety have a range of symptoms including tension, restlessness, hyperactivity, worry and fear. For autistic children, anxiety might show up as asking questions over and over again, hurting themselves, or having trouble getting to sleep.

How common is anxiety in autistic children?
Anxiety is common in autistic children, and 40-60% of autistic children have it.

Social anxiety is one of the most common anxiety disorders. Social anxiety probably happens because autistic people often have a style of interacting that can make socialising difficult for them.

Treatment, therapies and supports for anxiety
Cognitive behaviour therapy and relaxation techniques can help children with anxiety. Sometimes children might need medicine too.

Find out more
Anxiety in autistic children and teenagers

Attention deficit hyperactivity disorder (ADHD)

Many children have difficulty with thinking before they act, sitting still and focusing. But in children with attention deficit hyperactivity disorder (ADHD), these behaviours can be extreme and have a big effect on their daily lives. The behaviours usually happen together, although some children can be mainly inattentive.

How common is ADHD in autistic children?
Autism and ADHD share some common characteristics. Many autistic children have behaviour that’s very similar to ADHD, and 30-80% meet the criteria for an ADHD diagnosis.

Treatment, therapies and supports for ADHD
Health professionals can work with children and teenagers to develop strategies to help them manage their ADHD. Doctors will sometimes prescribe stimulant medicines for children diagnosed with ADHD. These medicines improve the way the parts of the brain ‘talk’ to each other. This can help children with attention and self-regulation.

Find out more

• Attention deficit hyperactivity disorder (ADHD): children and teenagers
• Managing ADHD in children and pre-teens
• Managing ADHD in teenagers

Bipolar disorder

Bipolar disorder is a psychiatric condition. People with bipolar disorder have both extreme emotional highs (mania) and extreme emotional lows (depression).

The depression can be quite obvious – the person will probably have low mood, lack of motivation, trouble sleeping and poor appetite. Mania can be harder to spot. Its symptoms include extreme self-esteem, less need for sleep, more talking and higher activity levels than usual.

Children who have bipolar disorder have big and quick changes in mood and behaviour. When they’re going through these mood changes, they might also have trouble paying attention, sitting still and behaving appropriately.

How common is bipolar disorder in autistic children? 
There isn’t a lot of research into bipolar disorder and autism, but it suggests that bipolar disorder isn’t very common in young autistic children.

Treatment, therapies and supports for biopolar disorder
Treatment is usually long term. It often involves medicine. There are some behaviour therapies that can help.

Find out more
National Institute of Mental Health – Bipolar disorder

Down syndrome

Down syndrome is a genetic condition.

Most people have 23 pairs of chromosomes. People with Down syndrome (also called Trisomy 21) have an extra 21st chromosome. This causes characteristic facial features, developmental delays, intellectual disability, poor muscle tone, potential hearing and vision problems and congenital heart defects.

Down syndrome can be identified with tests during pregnancy. If it isn’t picked up then, it’s usually diagnosed at birth or in early infancy.

How common is Down syndrome in autistic children?
Only a small number of autistic children also have Down syndrome. This is because Down syndrome is uncommon, occurring in only 1 in 1100 births. On the other hand, autism is relatively common in children who have Down syndrome. Up to 40% of children with Down syndrome are also autistic.

Treatment, therapies and supports for Down syndrome
The health problems associated with Down syndrome can be treated, usually very well.

Find out more

• Down syndrome
• Down Syndrome Australia

Eating disorders

Eating disorders are serious mental illnesses that also affect physical health. The most common eating disorders are anorexia nervosa, bulimia nervosa, avoidant restrictive food intake disorder (ARFID) and binge eating disorder.

How common are eating disorders in autistic children?
Different eating behaviours are common in autistic children. These include avoiding foods, eating non-food items and picking at food without swallowing. They also include sensory sensitivities to certain types of food.

Some research has shown that people with certain types of eating disorders are more likely to be autistic than people without eating disorders. Less is known about how many autistic people have or develop eating disorders.

Treatment, therapies and supports for eating disorders 
A team of health professionals with expertise in different areas usually treats children with eating disorders. These health professionals develop individual treatment plans for children, which are tailored to children’s ages, illness stages, illness types and severity, underlying causes and other factors.

Find out more

• Eating disorders: pre-teens and teenagers
• Butterfly Foundation
• InsideOut

Fragile X syndrome

Fragile X is a genetic condition. It’s the most common cause of inherited intellectual disability.

Most boys with this condition have an intellectual disability, sometimes severe. In the early years this would be noticed as developmental delay. Girls with this condition are more likely to have learning difficulties than intellectual disability. Children with the condition have trouble communicating.

How common is Fragile X in autistic children? 
Fragile X is recognised as a genetic cause of autism, and autism is relatively common in children with Fragile X. But only a small number of autistic children also have Fragile X because Fragile X occurs much less frequently than autism.

Treatment, therapies and supports for Fragile X 
Treatment usually involves speech pathology, occupational therapy and educational support.

Find out more

• Fragile X syndrome
• Fragile X Association of Australia

Gastrointestinal symptoms

The most common gastrointestinal symptoms for autistic people are chronic constipation, abdominal pain, diarrhoea and faecal incontinence. Other problems can include gastro-oesophageal reflux disease (GORD) and stomach bloating.

It’s not clear why autistic children have relatively high rates of gastrointestinal symptoms, but it might be because of altered gut bacteria, increased gut permeability, longer food transit time through the gut, or low fibre intake.

How common are gastrointestinal symptoms in autistic children?
Autistic children and children with developmental delays or disabilities appear to have more gastrointestinal symptoms than other children.

Treatment, therapies and supports for gastrointestinal symptoms
Because there are many reasons why a child might have gastrointestinal symptoms, the child will need a thorough medical examination before starting any treatment.

There’s no evidence to support the general use of a gluten-free or casein-free diet. But like some typically developing children, autistic children might have gluten intolerance, or other food sensitivities, allergies or intolerances. If this is the case, specific diets can help.

Find out more
Autism Help – Gastrointestinal tract problems

Intellectual disability and developmental delays

Intellectual disability can be diagnosed when a child who is 6 years or older has an IQ below 70 as well as difficulties with daily tasks. In children under 6 years, the term developmental delay is used when children have significant cognitive and language delays.

Intellectual disability varies from person to person. Autistic children with intellectual disability might have uneven skills, so there might be some things that they’re quite good at and others they find hard.

In most cases, autistic children have more trouble with verbal skills – like talking, listening and understanding – than with non-verbal skills like doing puzzles or drawing.

How common is intellectual disability in autistic children?
In the past, it was thought that 50-60% of autistic children had intellectual disability or developmental delays. But it’s now thought to be 20-30%, with another 20-25% having borderline intellectual disability with an IQ of 71-85.

This drop might be because IQ testing for autistic children has improved, support and education is better at addressing autistic children's learning needs, and more children without intellectual disability are being diagnosed with autism.

Some researchers have argued that some children’s developmental delays might be caused by their social learning difficulties, rather than being a separate condition.

Treatment, therapies and supports for intellectual disability
There can be significant improvements over time in some very young autistic children who have developmental delay and get good early therapy and support. Other children who have a more significant developmental delay might still have a lower than typical IQ when they’re older.

There’s no cure for intellectual disability, but it can be managed. Early intervention and education can support people with intellectual disability and their families.

Find out more
Intellectual disability

Language delay, speech disorder and developmental language disorder

Language delay is when young children have difficulties understanding and/or using spoken language. If a child has a language delay that doesn’t go away, this might be a sign of a developmental language disorder. Children with developmental language disorders have language difficulties that affect their everyday lives and make it harder for them to learn to read.

A speech (sound) disorder is when children have difficulty pronouncing the sounds in words. Children with speech disorders don’t necessarily have language delay or developmental language disorder.

Not all children who have language delay have problems with speech.

How common are language delays and disorders in autistic children?
Autistic children have particular ways of communicating with others. They might also have difficulties with other aspects of language, but their speech development is the least likely to be affected. Of autistic children, 25-50% don’t communicate verbally or use only use a few words.

Treatment, therapies and supports for language delays and language disorders 
Speech pathologists help children with speech and language problems. They might recommend individual or group programs that build language skills. They might also help children develop other ways to communicate, like pictures or picture boards, key word signing or speech generating devices.

Find out more

• Language delay
• Speech (sound) disorder

Motor difficulties

Children with motor difficulties might have difficulties with gross motor skills, like balance problems, clumsiness or walking problems. Or their difficulties might be related to fine motor skills, like problems with grasping objects, writing or using cutlery. Motor difficulties can also affect children’s mouths, making them hard to understand.

Muscle weakness often causes these difficulties.

Some children have difficulties with coordination even though their muscles are fine.

How common are motor difficulties in autistic children?
About 80% of autistic children have some form of motor difficulty. Motor difficulties can happen in babies, children and adults, often before autism characteristics become obvious. Some researchers think these difficulties might be early signs of autism.

Treatment, therapies and supports for motor difficulties
Occupational and physical therapy can be used to help children with motor difficulties.

Find out more
Skills for action – Autism and motor abilities

Obsessive compulsive disorder (OCD)

Obsessive compulsive disorder (OCD) is a type of anxiety disorder.

People with OCD have thoughts that they don’t want but can’t get out of their heads. They behave in repetitive and compulsive ways to deal with these thoughts. For example, they might wash their hands over and over again, or arrange or count objects in patterns, as a way of cancelling out bad thoughts with good thoughts.

Some people experience obsessive thoughts about flaws in their appearance that other people can’t see. This type of obsessive thinking is called body dysmorphia.

How common is OCD in autistic children?
It’s hard to know how common OCD is among autistic children because these children also tend to have repetitive thoughts and behaviour. Because intense and repetitive behaviour is more common in younger autistic children, OCD seems to be more common at younger ages.

Research suggests that there might be some genetic links between OCD and autism.

Treatment, therapies and supports for OCD
OCD can be treated with behaviour therapy, cognitive therapy, medicines or a combination of these.

Find out more
Obsessive-compulsive disorder (OCD) in children and teenagers

Seizures and epilepsy

Epilepsy is the name for a range of brain conditions where a child has or is at risk of having repeated and unpredictable seizures because of abnormal electrical activity in the brain.

The abnormal electrical activity in the brain causes odd sensations and abnormal movement or behaviour. These are called convulsions or seizures. When a child has a seizure, there’s usually a temporary period of unconsciousness, a body convulsion, unusual movements or staring spells.

It can be hard to spot epilepsy in autistic children because some seizure symptoms can be similar to some autism characteristics, like failing to respond to your name or doing repetitive, tic-like behaviours.

How common are seizures and epilepsy in autistic children?
Of autistic people, 20-30% have epilepsy. Seizures are most common in children under 5 years and in teenagers.

Autistic people with moderate to severe intellectual disability, autistic people with neurological conditions (for example, cerebral palsy), or children who show regression in their skills are more likely to develop epilepsy.

There might also be a genetic relationship between seizures and autism.

Treatment, therapies and supports for seizures and epilepsy 
Treatment usually involves anti-epileptic medicine. There are some steps you can take to minimise the effects of epilepsy. These include making sure your child takes medicine on time, gets enough good-quality sleep and avoids situations that cause stress.

Find out more

• Epilepsy
• Epilepsy Australia

Sleep problems

The most common sleep problems in autistic children are trouble falling asleep and staying asleep, nightmares, night terrors and sleepwalking.

How common are sleep problems in autistic children?
Sleep problems are common among autistic children. About two-thirds of autistic children might have sleep problems at some time.

Treatment, therapies and supports for sleep problems
Good sleep habits can help. This includes:

• cutting out drinks with caffeine in the afternoon and evening
• getting sunshine and exercise throughout the day
• avoiding screen use in the hour before bedtime
• having a regular bedtime routine.

Strategies like changing bedtime routines can also help, particularly for settling and night waking.

Medicine is another option, but health professionals generally recommend this only if behaviour therapies have failed. Melatonin is the only medicine currently thought to be helpful. ="glossary">

Find out more

• Better sleep autistic children 3-8 years: eight tips
• Sleep problems and solutions: autistic children 

Tourette disorder

Tourette disorder is a tic disorder. Tics are sudden, repetitive and uncontrollable movements and sounds. Tourette disorder is when children have movement tics and sound tics for longer than a year.

How common is Tourette disorder in autistic children?
About 5% of autistic children have Tourette disorder and another 9-12% have tics of some kind. Tourette disorder or motor tics are more common in children with moderate to severe intellectual disability.

Treatment, therapies and supports for Tourette disorder
Education and reassurance can help children understand the tics and learn strategies to manage them. Doctors might recommend specific behaviour therapies, or medicine, if the tics are severe or affecting daily life.

Find out more

• Tics, tic disorder and Tourette disorder
• Tourette Syndrome Association of Australia: What is Tourette Syndrome?

Tuberous sclerosis

Tuberous sclerosis is a genetic condition that causes abnormal growths in the brain and other vital organs. Symptoms can include white patches on the skin, facial rash, seizures, behaviour difficulties like hyperactivity, and intellectual disability.

How common is tuberous sclerosis in autistic children? 
Tuberous sclerosis isn’t very common among autistic children (0-4%). It’s more common if the person also has a seizure disorder (8-14%).

Treatment, therapies and supports for tuberous sclerosis  
Treatment focuses on managing symptoms and supporting the person and family.

Find out more
Tuberous Sclerosis Australia

Getting help

If you think your autistic child has another condition, talk with a health professional like your child’s GP, nurse or paediatrician. Depending on the condition, the professional might be able to order some tests, including a genetic test, or refer you to a specialist for further assessment and treatment.