Autism or ADHD, or can you have both?

Many people wonder if they have autism, ADHD, or both. These two conditions share some traits but also have clear differences. Understanding how they compare and overlap can help people make sense of their experiences. This post explains key differences and similarities between autism and ADHD, why they often occur together, and why a combined assessment can be helpful.

Diagram explaining neurodiversity

Attention versus processing differences

One of the main ways autism and ADHD differ is in how attention and processing work.

• ADHD mainly affects attention regulation. People with ADHD often struggle to focus on tasks, especially if they are boring or repetitive. They may be easily distracted by noises, movements, or their own thoughts. This can make it hard to complete tasks or follow instructions.

  
  

• Autism involves differences in how the brain processes information. People with autism might focus intensely on specific interests but find it hard to shift attention to other things. Their brains may process sensory input, language, or social cues differently, which can affect understanding and responses.

  
  

For example, a person with ADHD might start a project but get distracted by a phone notification and lose track. Someone with autism might focus deeply on a hobby but struggle to understand a conversation about feelings.

Social communication versus impulsivity

Social communication challenges and impulsivity also help distinguish autism and ADHD.

• Autism often involves difficulties with social communication. This includes understanding body language, tone of voice, or unspoken social rules. People with autism may find it hard to start or maintain conversations, interpret jokes, or recognise others’ emotions.

  
  

• ADHD is more associated with impulsivity. This means acting without thinking, interrupting others, or having trouble waiting their turn. Impulsivity can affect social interactions but in a different way than autism’s social communication differences.

  
  

For example, a person with autism might not pick up on sarcasm, while a person with ADHD might blurt out answers before a question is finished.

Sensory differences

Sensory experiences often differ between autism and ADHD but can overlap.

• Many people with autism have strong sensory sensitivities. They might be overwhelmed by loud noises, bright lights, or certain textures. This can lead to discomfort or anxiety in everyday environments.

  
  

• People with ADHD can also experience sensory issues but usually less intensely. They might seek sensory input through movement or touch to help focus or calm down.

  
  

For instance, a person with autism might avoid crowded places due to noise sensitivity, while someone with ADHD might fidget or tap their foot to stay alert.

Routines versus novelty seeking

How people respond to routines and new experiences varies between the two conditions.

• Autism often involves a preference for routines and predictability. Changes in schedule or environment can cause stress or confusion. Routines provide a sense of safety and control.

  
  

• ADHD tends to involve a craving for novelty and stimulation. People with ADHD may get bored easily and seek out new activities or experiences to stay engaged.

  
  

For example, a person with autism might follow the same daily routine carefully, while a person with ADHD might jump between hobbies or tasks frequently.

Autism, ADHD or both?

Emotional regulation

Both autism and ADHD can affect how emotions are managed, but in different ways.

• People with autism may experience intense emotions and find it hard to express or understand them. This can lead to meltdowns or shutdowns when overwhelmed.

  
  

• People with ADHD often struggle with impulsive emotional reactions. They might get frustrated or excited quickly and have difficulty calming down.

  
  

For example, a person with autism might withdraw when upset, while a person with ADHD might react loudly or abruptly.

Why autism and ADHD often co-occur

It is common for autism and ADHD to appear together. Research shows that about 30-50% of people with autism also meet criteria for ADHD. This overlap happens because both conditions involve differences in brain development and function.

Shared genetic factors and brain pathways may contribute to both. The co-occurrence means some people experience a mix of symptoms from both conditions, which can make diagnosis and support more complex.

Many people seek assessment because they relate to both, and a combined assessment helps clarify this

If you recognise traits from both autism and ADHD, a combined assessment can provide a clearer picture. Understanding which symptoms come from which condition helps guide effective support and strategies.

For example, knowing that attention difficulties stem from ADHD can lead to targeted focus techniques, while recognising sensory sensitivities from autism can guide environmental adjustments.

An assessment is not about labelling, it is about understanding. If you would like to learn more about how autism and ADHD assessments work, our guide explains the process and next steps, and you are welcome to contact CADS for a low-pressure conversation.