ADHD and Autism: A Guide to Overlap & Differences

• OVERVIEW
• SYMPTOMS
• ADULTS
• CHILDREN
• WOMEN
• DIAGNOSIS
• TREATMENT
• MEDICATION

Attention-deficit/hyperactivity disorder (ADHD) and autism are both neurodevelopmental conditions that manifest in childhood. They both affect communication and emotional regulation, among other areas. The overlapping symptoms can confuse individuals who may be experiencing one condition or, in some cases, both. Knowing which condition explains your symptoms better can provide clarity and direction towards navigating life with ADHD or autism (or both).

At AuDHD Psychiatry, we follow NICE‑aligned diagnostic frameworks to help you or your loved ones explore autism- and ADHD-related concerns in a structured, evidence-based way. Our neurodivergent-informed approach allows us to understand symptoms over time and explain what they may mean, so you can make informed decisions about next steps. In this guide, we explain the differences and similarities between ADHD and autism, how they affect daily life and how these conditions are evaluated.

Key Takeaways

• ADHD and autism, both lifelong neurodevelopmental conditions, have overlapping symptoms that complicate diagnosis.
• Further complicating a diagnosis is the potential for some individuals to have both conditions, which is referred to as AuDHD.
• Current research indicates that 50 per cent to 70 per cent of individuals with autism also have ADHD. In a separate poll on the co-occurrence of ADHD and autism, 45 per cent of people diagnosed or suspected to have ADHD said they had autism as well.
• Individuals with the co-occurrence of ADHD and autism generally exhibit more severe symptoms than those who have only one or the other. 
• Although more challenging than having one condition, the co-occurrence of autism and ADHD could also mean a person may excel in certain interests and have deep empathy.

What Is ADHD?

ADHD is a lifelong neurodevelopmental condition that affects how your brain develops and works. It influences how your brain manages impulse control, activity levels and attention. It is a common condition diagnosed in children and adults. There are three ADHD types, each presenting in three different ways:

• Inattentive – overlooks or misses details, has difficulty remaining focused during lectures, conversations, or lengthy reading, and is easily distracted.
• Hyperactive-impulsive ADHD – fidgets or squirms in seat, runs about or feels restless, often on the go, talks excessively, interrupts or intrudes on others during conversations.
• Combined – the most common type of ADHD.

Symptoms will depend on what type of ADHD the individual has, as defined in the Statistical Manual of Mental Disorders (DSM-5).

What Is Autism?

Autism is also a lifelong neurodevelopmental condition that covers a spectrum of characteristics. In general, it’s characterised by restricted activities, behaviours and interests, along with difficulties with social interactions and communication.

Autism spectrum disorder, according to DSM-5, has three levels of severity. Each level indicates the degree of support an individual will need.

• Level 1 autism – requires support
• Level 2 autism – requires substantial support
• Level 3 autism – requires very substantial support

ADHD vs Autism: The Key Differences

ADHD and autism are often confused for one or the other because symptoms tend to overlap. Both conditions have difficulties with attention and focusing, along with social and communication challenges. People with either ADHD or autism also struggle with executive functions, wrestling with organisation, time management and task switches.

In some cases, the two conditions co-occur, making diagnosis even more of a challenge.

How common is autism and ADHD together, also referred to as AuDHD? Current research indicates that 50 per cent to 70 per cent of individuals with autism also have ADHD. In a separate poll on the co-occurrence of ADHD and autism, 45 per cent of people diagnosed or suspected to have ADHD said they had autism as well.

There are differences, however, between the two. An autistic person needs routine and sameness, whereas an individual with ADHD gets bored easily and looks for new experiences. A person with autism will have intense, specialised interests, whereas a person with ADHD will have a short attention span.

Here’s a quick glance at the differences between ADHD and autism.

Area	ADHD	Autism
Main challenge	Impulse control and attention	Sensory sensitivities and social communication
Structure routine	Often difficult	Often preferred
Social behaviour	Distracted, impulsive	Social cues and reciprocity differences
Focus	Easily distracted, inconsistent	Intense, sustained interest
Sensory issues	Probable but secondary	Primary characteristic

The Co-occurrence of ADHD and Autism

Not many studies have been done to find out more about AuDHD. In what few studies have been performed, scientists have determined that individuals with the co-occurrence of ADHD and autism generally exhibit more severe symptoms than those who have only one or the other. For instance, hyperactivity and inattention are more evident. The intense experience of shared traits can create an internal struggle among the (sometimes) competing traits.

With AuDHD, it has also been observed that people with autism tend to have more ADHD symptoms, and people with ADHD tend to have more autistic traits.

The common traits of ADHD and autism in adults are:

• Executive dysfunction
• Social challenges
• Differences in eye contact
• Sensory differences
• Hyperfocus and intense interests
• Rejection sensitivity
• Sleep disturbances
• Hyperfocus and intense interests
• Difficulties with interoception, such as noticing when you are hungry

Similar to adults, children also exhibit:

• Excessive talking
• Fidgeting or squirming in their seat
• Inability to sustain attention
• Intruding on others

Although the challenges are much more difficult for people with autism spectrum disorder and ADHD, they can also excel in certain areas of interest and have incredible empathy. 

As we’ve mentioned time and again, people with ADHD or autism have unique experiences. Some nuances may be observed in different individuals who have been diagnosed with either condition or AuDHD. It is this uniqueness in experiences that compels the necessity of a private assessment.

Diagnosis: How ADHD and AutismAre Evaluated

An ADHD and autism diagnosis follows a structured evaluation process to determine an individual’s specific condition. A private assessment captures the person’s experiences, unique struggles and strengths, allowing specialists to come up with a tailored treatment and support programme.

At AuDHD Psychiatry, our neurodivergent psychologists follow a clinically validated process to ensure accuracy, clarity and compassionate support from beginning to end. 

Here’s what our six-step process looks like:

1. Book your appointment.
   Schedule a time that works for you.
2. Receive an autism assessment.
   Undergo a thorough assessment that looks at autism traits and patterns.
3. Interview with people close to you. (Optional) 
   A short interview with family members, friends and other people who spend time with you.
4. Receive an ADHD assessment.
   Undergo a detailed assessment that looks at attention deficit hyperactivity disorder.
5. Go through a feedback session.
   Get a clear explanation of your results and how they’ll affect your daily life.
6. Discuss treatment and support.
   We go over a personalised treatment and support plan to help you manage AuDHD.

Frequently Asked Questions on ADHD and Autism

Life Can Be Manageable With ADHD and Autism

The co-occurrence of ADHD and autism can confuse and overwhelm any individual, including those around that individual. Some people might exhibit more ADHD symptoms, whereas others might present more autism traits. In all, a person who may have both conditions is likely to struggle with heightened experiences of opposing traits. 

Whether it’s you or someone dear to you, there is no reason to go through this journey alone. Clarity through private assessments is on hand, and personalised treatment and support plans offer hope for a more manageable future.

AuDHD Psychiatry specialises in neurodivergent assessment and care. If the traits mentioned here seem all too familiar, consider taking the next step. Start an assessment journey with a confidential consultation today.

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