ADHD or autism: how they differ and where they overlap

ADHD or autism? It is a question many parents end up asking, sometimes after a teacher has mentioned one and a relative the other. The two conditions can look alike from the outside, they often occur together, and both are neurodevelopmental, meaning they relate to how the brain develops. But they are different conditions, and knowing which one, or whether both, are part of your child's picture makes a real difference to the help they get.

What is ADHD?

ADHD affects three areas: attention, activity levels and impulse control. A child with ADHD may be easily distracted, forgetful and disorganised. They may also be restless, fidgety and quick to act or speak without thinking. Some children have mainly concentration difficulties, some are mainly hyperactive and impulsive, and many have both. Our guide to the types of ADHD in children explains this in more detail.

What is autism?

The NHS describes autism as a difference in how the brain develops that affects how a person sees and experiences the world. Autistic children may:

• communicate differently, for example starting to talk later, making less eye contact or finding non-literal language and sarcasm hard
• find it hard to join in with other children or to make close friendships
• have intense interests
• rely on routines, and become very distressed by change
• react strongly, or very little, to noise, light, touch, smells or tastes
• repeat movements or phrases, sometimes called stimming

Autism is something a child is born with. It is not an illness, and the NHS is clear that it is not caused by vaccines or medicines.

ADHD or autism: where the signs overlap

Some behaviours can appear in both conditions, which is why parents and teachers can find it hard to tell them apart. The same behaviour may have quite a different reason behind it.

• Not listening in class. A child with ADHD may drift off because their attention is pulled elsewhere. An autistic child may be absorbed in a topic they care about, or overwhelmed by the noise of the room.
• Difficulty with friendships. A child with ADHD may interrupt, struggle to wait their turn or act on impulse. An autistic child may find the unwritten social rules confusing, or prefer their own company.
• Big emotional reactions. In ADHD these are often linked to frustration and acting before thinking. In autism they are often linked to sensory overload, uncertainty or a change in routine.
• Restlessness. A child with ADHD may fidget because they cannot keep still. An autistic child may move or rock to help them feel calm or regulated.

Put simply, ADHD tends to make routine and focus hard to hold on to, while autism often brings a strong need for routine and sameness. Many children, though, do not fit neatly into one picture.

Can a child have ADHD and autism?

Yes, and it is common. The NHS notes that ADHD is more common in autistic people, and NICE lists autism among the conditions in which ADHD is seen more often. Since 2013 doctors have been able to diagnose autism and ADHD together, so one does not rule out the other.

This matters because a child with both may need help with each. Support for ADHD, such as breaking tasks down and building in movement breaks, can sit alongside support for autism, such as preparing for changes and adjusting the sensory environment. When only one condition is recognised, the other can be mistaken for "bad behaviour" or "not trying".

Neither ADHD nor autism is caused by parenting. If you have been made to feel otherwise, our page on when parents feel blamed in ADHD pathways may help.

Autism and ADHD in teenage girls

Both conditions can be harder to spot in girls, and the teenage years are often when difficulties finally surface.

NICE says ADHD is thought to be under-recognised in girls and women. They are less likely to be referred, more likely to go undiagnosed, and more likely to be given a different diagnosis instead. Girls with ADHD more often have the inattentive presentation: daydreaming, forgetfulness and disorganisation, rather than disruptive behaviour.

Autistic girls, the NHS explains, may mask their differences. They may copy their friends, stay quiet when things are difficult and seem to cope socially, then come home exhausted. Masking takes a great deal of effort, and not every girl knows she is doing it.

In teenage girls, the first signs that something is wrong may be anxiety, low mood, school refusal or difficulties with eating, rather than the classic signs of either condition. The NHS notes that autistic girls are more likely to have mental health problems such as anxiety, depression or an eating disorder. If your daughter is struggling in these ways, it is worth asking whether ADHD, autism or both could be underneath. Our guide to ADHD in girls has more on this.

What happens at BZ Clinic if autism is suspected

BZ Clinic assesses ADHD only. We do not carry out autism assessments.

Our doctors are consultant paediatricians, so during an ADHD assessment they look at your child's development and general health as well as their attention and behaviour. As part of this, the doctor screens for other conditions, including autism. If the doctor thinks autism may be part of the picture, they will explain why and signpost you to the right next step.

For autism, the NHS route usually starts with your GP, who can often refer to a local autism team. For school-age children, the school may need to make the referral. An autism assessment is usually carried out by a team and can involve several appointments.

If your child already has an autism diagnosis and you are wondering about ADHD, we can assess for ADHD in the usual way. You can contact the clinic directly without a GP referral. Read more about a private ADHD assessment for your child.

Other conditions to keep in mind

ADHD and autism are not the only conditions that can overlap. Anxiety, learning difficulties such as dyslexia, coordination difficulties such as dyspraxia, tics and sleep problems can all affect attention and behaviour. Our guide to ADHD and related conditions explains what a paediatrician looks for alongside ADHD.

Questions parents ask