Is it Autism or ADHD, or both?

One of the most common things I hear in my rooms is:

“I relate to autism… but I also relate to ADHD. How do you actually tell the difference?”

It’s a very reasonable question. If you’ve spent any time reading about either, the overlap can feel enormous. Executive functioning difficulties. Sensory sensitivities. Emotional overwhelm. Social struggles. Hyperfocus. Burnout. Feeling “different.”

At first glance, it can seem like the same story told with slightly different language.

But clinically, they are not the same, and understanding the difference isn’t about spotting one or two traits. It’s about understanding the pattern across a lifetime.

Let’s start with the obvious similarities, and then we’ll move into the more nuanced territory.

The Shared Surface

Both autism and ADHD are neurodevelopmental. They shape how the brain processes information from early childhood onward. So it makes sense that there is overlap.

Many people with either condition describe:

• Difficulty organising and planning

• Intense interests or periods of hyperfocus

• Sensory sensitivities

• Emotional dysregulation

• Social fatigue

• A lifelong sense of being out of step

This overlap is real. It’s also why so many adults begin questioning one diagnosis after identifying with the other.

And importantly — it is entirely possible to have both.

Research increasingly shows that co-occurrence is common. They are not mutually exclusive diagnoses.

But while they may look similar from the outside, they often feel very different internally. And that internal experience is something experienced clinicians pay close attention to.

Where the Differences Begin

Very broadly speaking, ADHD is primarily about regulation — of attention, energy, and impulse. The person often knows what they need to do, but struggles to activate, sustain, or inhibit behaviour consistently. Focus can be highly variable. Motivation can be interest-driven. There’s often a restless or urgent quality to the system.

Autism, on the other hand, is primarily about differences in social communication and patterns of restricted or repetitive thinking and behaviour. Social interactions may feel effortful or cognitively processed rather than intuitive. There is often a strong need for predictability, depth of interest, and consistency.

But here’s where it becomes more complex.

Someone with ADHD may struggle socially because they interrupt, miss details, drift off, or react impulsively. Someone autistic may struggle socially because the implicit rules are not intuitive and require conscious analysis. Externally, both people might say, “I find social situations hard.” Internally, the mechanisms are quite different.

A good assessment isn’t just about what happens. It’s about why it happens.

Developmental Patterns Matter

One of the most important parts of any neurodevelopmental assessment is understanding early childhood.

Autism is present from very early in life, even in high-masking individuals. There are usually subtle signs in early play, sensory responses, rigidity, peer relationships, or communication style — even if those signs were misunderstood at the time.

ADHD also begins in childhood, but tends to show up more clearly as distractibility, impulsivity, difficulty sustaining effort, inconsistent academic performance, or high activity levels.

When social difficulties or executive problems emerge later in life — for example after trauma, anxiety, burnout, or chronic stress — that points us in a different direction diagnostically.

It’s not just about current traits. It’s about the trajectory.

Masking and Compensation

Particularly in women and high-functioning adults, masking can blur the clinical picture considerably.

Many autistic adults describe years of consciously studying social interactions. They rehearse. They script. They mimic. They force eye contact. They suppress movements that feel regulating. They learn how to “perform” social competence.

From the outside, they may appear socially capable. Internally, the process is cognitively effortful and exhausting.

ADHD masking looks different. It often involves anxiety-driven productivity, last-minute urgency, perfectionism, or overworking to compensate for disorganisation.

Understanding what is automatic versus what is effortful is often central to teasing apart diagnoses.

Executive Function: Same Problem, Different Driver

Executive functioning difficulties are shared territory.

In ADHD, the difficulty is often about regulation. The intention is there. The knowledge is there. The activation falters.

In autism, executive challenges often relate more to cognitive flexibility. Shifting gears can be hard. Unexpected change can be destabilising. The system prefers predictability.

When someone has both, it can feel internally contradictory, ie. craving novelty but needing sameness. Wanting structure but struggling to maintain it. That internal push–pull is something I see often in combined presentations.

Emotional Regulation

Emotional dysregulation in ADHD often has a rapid, reactive quality. Emotions can flare quickly and intensely, sometimes resolving just as fast.

In autism, emotional overwhelm is often tied to sensory overload, social fatigue, cognitive strain, or disrupted expectations. The nervous system becomes overloaded.

Again, outwardly these might both look like “overreacting.” Clinically, they are not the same process.

The Bigger Picture

When I assess someone, I’m not looking for isolated traits. I’m looking for patterns:

• How consistent are these traits across environments?

• How early did they begin?

• What feels intuitive versus effortful?

• What explains the whole picture most coherently?

• Are there alternative explanations — anxiety, trauma, depression, intellectual profile, personality style?

Diagnosis isn’t about tallying symptoms. It’s about determining the most accurate explanation for the person’s lifelong pattern of functioning.

And sometimes, the answer is both autism and ADHD (which frequently co-occur).

Sometimes it’s one.

Sometimes it’s neither, but something else entirely.

The goal is clarity, not labelling for its own sake.

When to Seek an Assessment

Not everyone who relates to autistic or ADHD traits needs a formal diagnosis.

You might consider seeking assessment if:

• Your difficulties are causing significant functional impairment (work, study, relationships, daily life).

• You are repeatedly burning out and can’t understand why.

• You need workplace or university accommodations.

• You are considering medication (for ADHD).

• You want formal clarity for personal understanding.

• You require documentation for NDIS or other supports.

But equally, you may not need a diagnosis to make meaningful changes.

Many people benefit simply from understanding their cognitive style. They adjust expectations. They create structure. They reduce sensory load. They give themselves permission to operate differently.

A formal diagnosis is most useful when it changes access — to medication, accommodations, funding, or targeted support.

It is not required for self-compassion, self-knowledge, or strategy development.

Final Thoughts

If you’re confused about whether you’re autistic, ADHD, both, or neither — that confusion is understandable. The overlap is real. The nuance is real. And the internal experience matters.

A thoughtful assessment is less about proving something is “wrong,” and more about understanding how your brain works.

And that understanding, diagnosis or not, is often what brings the most relief.

Elizabeth Talbot

Clinical Psychologist

B Psych (Hons), M Psych (Clin), MAPS

Elizabeth Talbot is a Clinical Psychologist and the Principal Psychologist at Clinical Therapy. Whilst Elizabeth enjoys her clinical work, she is also a lover of behavioural science and has a keen research interest in the psychology of decision making, moral reasoning, cognitive biases, magical thinking, and conspiratorial beliefs.

Content note: Unless otherwise labelled, all blog posts are intended as discussion pieces, and are not academic texts. Articles pertaining to research or making an academic argument will be labelled as such and include supporting evidence/references. All examples (including client names) are fictitious, to illustrate a point, and are not based on actual clients.