Autism: Co-occurring Conditions
Autism rarely comes alone. Understanding common co-occurring conditions ensures your child receives comprehensive support, not just partial treatment.
of autistic people have at least one co-occurring condition
have two or more co-occurring conditions
have ADHD alongside autism
experience significant sleep difficulties
When autism co-occurs with other conditions:
- Each condition can mask or complicate the other
- Treatment for one may not address the other
- Some strategies for one may worsen the other
- Partial diagnosis leads to partial support
Comprehensive assessment should always consider co-occurring conditions.
Common co-occurring conditions
ADHD co-occurs with autism far more often than chance would predict. Until 2013, diagnostic guidelines prevented dual diagnosis, meaning many received only partial support.
Signs to watch for:
- •Difficulty sustaining attention (beyond autistic focused interests)
- •Impulsivity that isn't just social awkwardness
- •Hyperactivity or restlessness
- •Executive function difficulties beyond autism alone
- •Working memory challenges
Clinical note:
Both can affect attention and social functioning, but mechanisms differ. ADHD is about regulation; autism is about different processing. Both may need addressing.
Anxiety is extremely common in autism and may be even more common than ADHD. It can result from the unpredictability of social situations, sensory overwhelm, and years of negative experiences.
Signs to watch for:
- •Excessive worry, especially about social situations
- •Physical symptoms: stomach aches, headaches
- •Avoidance behaviours
- •Difficulty with new situations or changes
- •Sleep difficulties
Clinical note:
Anxiety in autism often has specific triggers (unpredictability, sensory issues, social demands). Traditional anxiety treatment may need adaptation.
Sleep problems affect the majority of autistic children and persist into adulthood. This can include difficulty falling asleep, frequent waking, and early morning waking.
Signs to watch for:
- •Difficulty falling asleep (racing mind, sensory sensitivity)
- •Frequent night waking
- •Early morning waking
- •Irregular sleep-wake patterns
- •Reduced need for sleep (in some)
Clinical note:
Sleep problems worsen autism symptoms and vice versa. Addressing sleep is often a priority before other interventions.
Selective eating in autism goes beyond "picky eating". It often involves sensory aversions to textures, smells, or appearances, and can significantly limit nutrition and social participation.
Signs to watch for:
- •Extremely limited food repertoire
- •Strong sensory aversions (textures, colours, smells)
- •Distress when preferred foods unavailable
- •May only eat specific brands or preparations
- •Difficulty eating in unfamiliar settings
Clinical note:
ARFID (Avoidant/Restrictive Food Intake Disorder) is the clinical term when eating is significantly restricted. It's not about control or defiance.
GI problems including constipation, diarrhoea, and abdominal pain are more common in autistic people. These can cause or worsen behavioural issues and should be investigated.
Signs to watch for:
- •Chronic constipation (very common)
- •Recurrent abdominal pain
- •Diarrhoea or irregular bowel patterns
- •Food intolerances
- •Increased irritability or behaviour changes (may signal GI discomfort)
Clinical note:
Autistic children may not communicate GI discomfort verbally. Behaviour changes or posturing may be the only sign.
About a third of autistic people also have an intellectual disability (IQ below 70). However, intelligence is often underestimated due to communication difficulties or test design.
Signs to watch for:
- •Significant delays in adaptive functioning
- •Learning at a slower pace than peers
- •Needing substantial support for daily living
Clinical note:
Many autistic people without ID are highly intelligent. Conversely, autistic people with ID have the same rights to support, communication, and quality of life.
Autistic people have significantly elevated rates of mental health conditions:
Depression
4x higher risk than general population
Anxiety disorders
Present in 40-70% of autistic people
Suicidal ideation
Significantly elevated risk, especially in those who mask
Mental health problems in autism often result from years of not fitting in, masking, bullying, and unsupportive environments - not from autism itself. Early support and acceptance can be protective.
- Has ADHD been considered and screened for?
- Should we investigate anxiety or mood difficulties?
- Are sleep problems being addressed?
- Should GI issues be investigated?
- Is the eating pattern concerning enough to warrant assessment?
- How will co-occurring conditions affect the support plan?