Having ADHD and Autism (AuDHD): A Comprehensive Guide
ADHD and Autism often overlap. Learn how they present together, what AuDHD looks like, and how to get the right support as an adult.
ADHD and Autism: A Tale of Two Diagnoses
For many adults, learning about ADHD and autism brings both relief and confusion. You might recognise yourself in ADHD descriptions—the racing thoughts, difficulty focusing, constant search for stimulation. But then autism traits feel familiar too—the need for routine, sensory sensitivities, exhaustion from social situations.
How can you crave novelty and need predictability? Be impulsive yet cautious? Seek stimulation but feel easily overwhelmed?
These aren't contradictions. They're the reality of experiencing both conditions—something far more common than most people realise.
ADHD and autism are lifelong neurodevelopmental conditions that affect how the brain develops and processes information. Many people only recognise these patterns in adulthood, often when years of coping strategies finally become unsustainable.
Research shows that 30–50% of people with autism also meet criteria for ADHD. This overlap is increasingly recognised in adult assessments. This guide will help you understand how these conditions differ, how they interact, and what it means when both are present.
Can I Have Both ADHD and Autism?
Yes. The psychiatric field now formally recognises that both conditions can be present in the same person.
For a long time, however, this wasn't the case. Earlier diagnostic manuals (specifically the DSM-IV, used until 2013) actually prohibited diagnosing both conditions simultaneously. If you had an autism diagnosis, any attention difficulties were attributed to autism itself, not recognised as a separate condition requiring its own treatment.
Why did the scientific community take this position?
The reasoning was based on the theoretical understanding at the time:
The "Pervasive" Nature: The diagnostic category was called "Pervasive Developmental Disorders" because autism was understood to affect all domains of development—including attention, executive function, social communication, and behaviour. The thinking was: if autism affects everything, then attention problems would naturally be part of that picture.
Diagnostic Parsimony: A core principle in psychiatric diagnosis is not to diagnose two conditions when one explains all the symptoms. If attention difficulties were intrinsic to autism, diagnosing both would be redundant.
Limited Research: At the time, there was limited research specifically examining whether ADHD symptoms in people with autism represented a separate condition or were simply how autism manifested in the attention domain.
This approach was based on the scientific framework and clinical observations available at that time. However, it meant that countless people with both conditions were left without the full picture of their neurology, often going years without proper support for ADHD symptoms.
What Changed?
Research evidence accumulated through the 1990s and 2000s showing:
ADHD symptoms in people with autism had distinct characteristics
ADHD-specific treatments (like stimulant medications) produced improvements
Genetic studies revealed overlap but also independence between conditions
Co-occurrence rates far exceeded chance
Clinical outcomes improved when both conditions were recognised and treated
This led the DSM-5 (2013) to remove the exclusion, formally allowing co-diagnosis when criteria for both are met. The World Health Organisation's ICD-11 (2018) followed suit.
How Common Is The Overlap between ASD and ADHD?
Current research shows:
From autism to ADHD: Approximately 30–50% of people with autism meet the criteria for ADHD. In clinical samples (people actively seeking assessment), this rises to 50–70%. Meta-analyses report that around 38–40% of people with autism have clinically significant ADHD symptoms.
From ADHD to autism: The bidirectional relationship is also significant. Studies show that traits associated with autism are substantially elevated in people with ADHD compared to the general population.
A large-scale study of 3.5 million adults found that 26.7% of adults with autism (without intellectual disability) also had ADHD—nearly 10 times higher than the general population rate of around 2.7%.
This level of co-occurrence points to genuine biological overlap between these conditions, which we'll explore in depth later.
Understanding ADHD: What Does It Actually Look Like?
ADHD (Attention-Deficit/Hyperactivity Disorder) is fundamentally a neurodevelopmental condition affecting attention regulation, impulse control, and executive functioning. This means it impacts how you focus, plan, organise, start tasks, manage time, regulate emotions, and shift between activities.
The Core Features of ADHD
Inattention isn't just "not paying attention"—it's a difficulty regulating where your attention goes:
Struggling to sustain focus on tasks, especially ones that aren't immediately engaging
Being easily pulled away by external stimuli or internal thoughts
Difficulty filtering out irrelevant information
Losing track of belongings, conversations, or what you were just doing
Starting many projects but struggling to finish them
Hyperactivity changes across the lifespan:
In children: physical restlessness, constant movement, difficulty sitting still
In adults: often manifests as internal restlessness, fidgeting, needing to stay busy
A feeling of being "driven by a motor" even when you want to relax
Impulsivity shows up in multiple ways:
Acting on impulses without thinking through consequences
Interrupting others because thoughts feel urgent
Difficulty waiting or delaying gratification
Making quick decisions without considering alternatives
Emotional impulsivity—feelings that spike quickly and intensely
Executive Function Challenges:
Time blindness—difficulty estimating how long things take or how time is passing
Working memory difficulties—losing track of multi-step instructions
Planning and organisation challenges
Difficulty initiating tasks (even ones you want to do)
Trouble shifting between activities
The ADHD Experience
People with ADHD often describe their mind as having too many browser tabs open at once. Thoughts move quickly, jumping from topic to topic. There's often a strong need for novelty and stimulation—when something is interesting, you can hyperfocus for hours, but when it's not, maintaining attention feels impossible.
The world can feel either overstimulating (too many inputs demanding attention) or understimulating (leading to boredom and restlessness). Dopamine-driven motivation means you're drawn to what's new, urgent, or immediately rewarding, whilst long-term goals feel distant and abstract.
Understanding Autism: Beyond Social Communication
Autism (Autism Spectrum Disorder or ASD) is a neurodevelopmental condition that affects how a person processes, experiences, and interacts with the world. Whilst it's often described primarily through social communication differences, this narrow focus misses the complexity of the experience.
The DSM-5 defines autism by two core domains:
Persistent differences in social communication and interaction
Restricted, repetitive patterns of behaviour, interests, or activities (including atypical sensory processing)
But to truly understand autism, we need to look beyond these clinical criteria to the broader experience of information processing, sensory experience, and cognitive style.
Autism as a Different Way of Processing Information
At its core, autism involves differences in how the brain processes and integrates information from the world. This affects multiple domains:
Sensory Processing (Often Central, Not Secondary): For many people with autism, sensory experience isn't just a feature—it's fundamental to how they experience reality:
Heightened sensitivity (hypersensitivity) to lights, sounds, textures, smells, or tastes
Or reduced sensitivity (hyposensitivity) requiring more intense input
Difficulty filtering background information from important signals
Sensory overload leading to shutdown or meltdown
Specific sensory needs that help with regulation
Pattern Recognition and Systemising:
Strong ability to notice patterns others miss
Preference for understanding systems and rules
Detailed, focused thinking (sometimes called "bottom-up" processing)
Difficulty with ambiguity or unclear expectations
Information Processing Style:
May process information more thoroughly but more slowly
Strong attention to detail (which can be both strength and challenge)
Difficulty filtering relevant from irrelevant information
Different balance between local details and global patterns
Social Communication and Interaction Differences
The social aspects of autism are real, but they emerge from these broader processing differences:
Social Communication:
Difficulty reading social cues, facial expressions, or tone of voice
Challenges understanding unwritten social rules
Atypical eye contact patterns (too much, too little, or effortful to maintain)
Preference for direct, literal communication over social scripts
Difficulty with back-and-forth conversation flow
Not always picking up on what's left unsaid
Social Interaction:
Social situations are cognitively demanding (requiring active processing of complex, rapidly changing information)
Difficulty predicting others' behaviour or intentions
Challenges with reciprocal social engagement
May prefer solitary activities or interactions around shared interests
Social exhaustion after interaction, requiring recovery time
Importantly, social difficulties in autism aren't about lacking empathy or not caring about others. Many people with autism feel empathy deeply but may express it differently or struggle to read what others need.
Restricted and Repetitive Patterns
Deep, Focused Interests:
Intense engagement with specific topics (sometimes called "special interests")
These bring genuine joy, meaning, and often expertise
Not obsessions to be eliminated, but meaningful engagement
Routines and Predictability:
Strong preference for sameness and routines
Distress when routines are disrupted or environments change unexpectedly
Routines reduce cognitive load and provide security
Difficulty with transitions or unexpected changes
Repetitive Movements and Behaviours:
Stimming (self-stimulatory behaviour) like hand-flapping, rocking, or fidgeting
These serve regulatory functions (calming, focusing, or expressing emotion)
Specific ways of organising or arranging things
Repetitive language or echolalia
Cognitive and Thinking Style Differences
Monotropic Attention: Recent theory suggests people with autism may have "monotropic" attention—deep focus on fewer things at once, versus "polytropic" attention spread across many. This explains:
Intense focus when engaged with an interest
Difficulty shifting attention between topics
Overwhelm when too many demands compete for attention
Executive Function: Like ADHD (but often for different reasons), autism involves executive function challenges:
Difficulty with planning and organisation
Challenges with cognitive flexibility (shifting between tasks or approaches)
Need for external structure and support
Autism Support Levels
The DSM-5 recognises that autism exists on a spectrum of support needs, described through three levels:
Level 1 - "Requiring Support":
Noticeable difficulties with social communication without support in place
Inflexibility in behaviour causes significant interference
Difficulty initiating social interactions
May appear to have decreased interest in social interactions
Organisational and planning difficulties impede independence
Level 2 - "Requiring Substantial Support":
Marked difficulties in verbal and nonverbal social communication
Social impairments apparent even with supports in place
Limited initiation of social interactions
Reduced or abnormal responses to social overtures from others
Inflexibility, difficulty coping with change
Restricted/repetitive behaviours interfere with functioning across contexts
Distress or difficulty changing focus or action
Level 3 - "Requiring Very Substantial Support":
Severe difficulties in verbal and nonverbal social communication
Minimal initiation of social interactions
Minimal response to social overtures from others
Extreme difficulty coping with change
Restricted/repetitive behaviours markedly interfere with functioning
Great distress or difficulty changing focus or action
These levels aren't fixed—someone's support needs can vary across contexts, over time, or depending on stress, burnout, or available support.
The Experience of Autism
Many people with autism describe feeling like they're navigating a world designed by and for people with different wiring. Social situations can feel like trying to follow an unwritten rulebook everyone else seems to have memorised, whilst processing an overwhelming amount of sensory and social information simultaneously.
There's often a strong need for predictability and routine—not out of stubbornness, but because it reduces cognitive load and anxiety. When you know what to expect, you have mental energy for other things.
Deep interests bring genuine joy and can be sources of expertise and career success. Many adults with autism learn to "mask" or "camouflage" their natural traits to fit in, which works temporarily but is exhausting and unsustainable long-term.
The Seeming Paradox: How Can You Have Both?
This is where it gets interesting—and confusing. How can someone have ADHD (characterised by seeking novelty, impulsivity, difficulty with routines) AND autism (characterised by needing sameness, being cautious, loving routines)?
The answer is that they're not actually opposite conditions—they affect different aspects of brain function.
Think of it this way:
ADHD primarily affects your brain's "doing" systems:
Attention regulation
Impulse control
Motivation and reward processing
Executive function (planning, organising, initiating)
Time perception
Autism primarily affects your brain's "processing" systems:
Sensory information processing
Social information processing
Pattern recognition and prediction
Need for consistency to manage processing load
How you engage with interests and information
When both are present, you get what many people informally call "AuDHD"—a unique intersection where:
You might crave novelty (ADHD) but feel overwhelmed by unpredictability (autism)
You might be impulsive about starting new projects (ADHD) but need specific routines to actually complete them (autism)
You might hyperfocus intensely (ADHD meeting deep interests in autism)
You might be socially anxious (autism) but interrupt conversations because thoughts feel urgent (ADHD)
You might seek sensory stimulation when understimulated (ADHD) but also experience sensory overwhelm easily (autism)
These aren't contradictions—they're different neurological systems creating complex, layered experiences.
The Push and Pull Experience
Many people with both describe feeling caught between competing needs:
Routine vs Variety:
Your brain with autism craves predictable structure
Your ADHD brain gets bored with repetition
Result: You need novelty within structure, or routines that accommodate variety
Social Interaction:
Autism might make socialising cognitively exhausting
ADHD might make isolation boring and understimulating
Result: You want connection but in specific, manageable doses
Sensory Needs:
You might be hypersensitive to certain inputs (easily overwhelmed)
But hyposensitive or sensation-seeking for others (need more input)
ADHD restlessness adds another layer of needing movement/stimulation
Result: Complex, sometimes contradictory sensory needs
Emotional Regulation:
Both conditions affect emotional processing
ADHD brings emotional impulsivity and intensity
Autism can involve difficulty identifying and expressing emotions
Result: Feeling emotions intensely but struggling to understand or communicate them
The key insight: having both isn't about choosing which condition explains each symptom. It's about understanding how two different neurological patterns create a unique, complex experience.
What Does Having Both ASD and ADHD Look Like?
When ADHD and autism are both present, the experience is multi-layered and complex. Many people refer to this combination informally as AuDHD (short for Autism and ADHD). Whilst it's not a clinical diagnosis, the term has become widely used in neurodivergent communities to describe this overlapping experience.
The Daily Reality
Because ADHD and autism each influence the brain in different (and sometimes contrasting) ways, having both can feel like constantly managing an internal push and pull.
Morning routines might require specific structures (autism need for routine) but you struggle to follow them consistently (ADHD executive function challenges). You might forget steps or get distracted, then feel distressed when the routine is disrupted.
Work and productivity become complex. You might experience bursts of hyperfocus where you work intensely on something interesting—especially if it aligns with a deep interest. But then executive function challenges make it hard to switch tasks, time blindness means you miss deadlines, and sensory overwhelm in open office environments leaves you exhausted.
Social situations are particularly layered. You might struggle to read social cues (autism), interrupt because your ADHD brain is racing ahead, feel anxious about unwritten social rules (autism) but also talk a lot when excited or hyperfocusing (ADHD), and need extensive recovery time after socialising (autism) but also feel understimulated when alone (ADHD).
Decision-making involves multiple competing factors: autism wants extensive research and consideration, ADHD wants quick decisions before interest wanes. Both can lead to analysis paralysis or impulsive choices you later regret.
Why It's Exhausting to have ASD and ADHD
The main challenge many people describe is cognitive and emotional fatigue. When you're constantly managing competing needs (routine vs novelty, stimulation vs quiet), sensory overwhelm or understimulation, executive function challenges, social demands that don't match how your brain works, and the effort of masking or compensating, exhaustion builds up. This isn't laziness or poor stress management—it's the reality of your brain doing more processing work than neurotypical brains in the same situations.
Understanding Your Emotional World: Alexithymia and Interoception
One of the most significant (yet often overlooked) aspects of having ADHD and autism is how these conditions affect emotional processing. This is where two key concepts become crucial: alexithymia and interoception.
What Is Alexithymia?
Alexithymia means difficulty identifying and describing your own emotions. It's not about not having emotions—people with alexithymia often feel emotions very intensely. It's about struggling to:
Identify what specific emotion you're feeling
Distinguish between similar emotions (anxiety vs excitement, anger vs frustration)
Put feelings into words
Understand what triggered an emotional response
Research shows that approximately 50% of people with autism have alexithymia. It's also elevated in people with ADHD, though at lower rates than in autism. When both conditions are present, alexithymia is even more common.
This is a critical piece of the puzzle for understanding "emotional dysregulation" in ADHD and autism. It's not just that emotions are intense—it's that you're feeling something powerful but can't identify what it is, why it's happening, or how to communicate it to others.
What This Looks Like in Practice
Imagine someone asks: "How are you feeling about this situation?"
For someone with alexithymia, the internal experience might be:
A physical sensation (tightness in chest, restlessness, heaviness)
A general sense of "bad" or "uncomfortable"
But no clear label: Is this anxiety? Sadness? Anger? Overwhelm?
Or you might experience:
Delayed emotional processing—only recognising what you felt hours or days later
Difficulty explaining why you're upset, even when the feeling is intense
Expressing emotions through behaviour (irritability, withdrawal, shutdown) rather than words
Confusion when others ask "What's wrong?" because you genuinely don't know
This is why many people with ADHD and autism describe feeling "broken" or "emotionally immature"—you feel things deeply, but can't process or communicate them the way others expect.
Understanding Interoception
Interoception is your brain's ability to sense and interpret signals from inside your body:
Hunger and thirst
Need to use the toilet
Heart rate and breathing
Muscle tension
Temperature
Pain levels
Emotional arousal (the physical sensations of emotions)
This manifests as:
Not noticing you're hungry until you're shaky and irritable
Forgetting to drink water or use the toilet
Difficulty recognising when you're getting overwhelmed before reaching a breaking point
Uncertainty about whether you're hot, cold, or comfortable
Missing early warning signs of illness
Struggling to identify the physical component of emotions
How Alexithymia and Interoception Connect
Here's where it comes together: emotions have physical components. When you feel anxious, your heart might race. When you're angry, muscles tense. When you're sad, there's often a heaviness in your chest.
If your interoception is atypical, you might:
Not notice these physical signals clearly
Notice them but not connect them to emotional states
Feel the physical sensation but not have language for the emotion
Combined with alexithymia, this creates a situation where you're feeling something intensely, experiencing physical sensations, but unable to identify what emotion you're having or why.
This is why "emotional regulation" strategies that work for neurotypical people often fail for those with both conditions. You can't regulate an emotion you can't identify.
The ADHD Component: Emotional Dysregulation
ADHD adds another layer to emotional processing: emotional dysregulation, impulsivity and intensity.
In ADHD, emotions:
Come on quickly and intensely
Feel urgent and demanding of immediate response
Can shift rapidly
May not match the "size" of the trigger (small frustrations feel massive)
When combined with autism's alexithymia and interoceptive differences, you get intense emotions that appear suddenly, without clear identification of what the emotion is, and difficulty understanding what triggered it, leading to behavioural responses (shutdown, meltdown, impulsive reactions).
Why This Understanding Matters
Recognising alexithymia and interoception challenges is crucial because:
It's not your fault: This isn't about emotional immaturity. Your brain processes emotional information differently.
It explains why standard advice doesn't work: "Just identify your feelings" or "use your words" isn't helpful when your neurology makes this genuinely difficult.
It opens different strategies: Learning to recognise physical patterns associated with emotions, creating external tools (emotion wheels, body scan checklists), building recovery routines for after emotional overwhelm, giving yourself permission to say "I'm feeling something intense but I can't identify it yet."
It helps loved ones understand: Partners, family, and friends often misinterpret alexithymia as not caring or being emotionally distant, when the reality is you care deeply but struggle with identification and expression.
Many people with both conditions describe this as one of the most validating pieces of self-knowledge—understanding that the disconnect between feeling emotions intensely and being unable to name or explain them is a recognised neurological pattern, not a personal failing.
The Sensory Experience: When Your AuDHD Brain Processes Input Differently
Sensory processing differences are a hallmark of autism, and whilst they're not a formal ADHD criterion, sensory sensitivities are common in ADHD as well. When both conditions are present, the sensory experience becomes particularly complex and can significantly impact daily functioning.
What Are Sensory Processing Differences?
Your brain constantly receives information from:
External senses: sight, sound, touch, taste, smell
Proprioception: awareness of body position and movement
Vestibular sense: balance and spatial orientation
Interoception: internal body signals (covered in the previous section)
In autism, this sensory information is often processed differently—either amplified (hypersensitivity) or dampened (hyposensitivity), and sometimes both for different types of input.
Hypersensitivity: When Everything Is Too Much
Many people with autism (and some with ADHD) experience heightened sensory sensitivity:
Sound:
Background noise that others tune out feels overwhelming
Multiple conversations in a room become painful chaos
Specific frequencies (fluorescent light buzz, certain voice pitches) are intolerable
Unexpected sounds trigger startle responses
Need for quiet to concentrate or recover
Vision:
Bright lights are painful, not just uncomfortable
Fluorescent or flickering lights cause headaches or overwhelm
Difficulty with visual clutter or busy patterns
Strong preference for dim, controlled lighting
Touch:
Certain fabric textures are unbearable against skin
Clothing tags, seams, or tight clothing cause distress
Light touch is more uncomfortable than deep pressure
Difficulty tolerating hugs or casual physical contact
Sensitivity to temperature extremes
Smell and Taste:
Intense reactions to smells others barely notice
Food textures and tastes are extremely important
Strong preferences or aversions to specific foods
Difficulty in environments with competing smells (perfume, food, cleaning products)
Hyposensitivity: When You Need More Input
Some people have reduced sensitivity to certain sensory input:
Not noticing temperature extremes (too hot or cold)
High pain tolerance or delayed pain recognition
Seeking intense flavours or textures
Enjoying loud music or intense visual stimulation
Needing movement or physical input to feel grounded
When Both Conditions Are Present
When ADHD and autism co-occur, sensory experiences become even more complex:
Simultaneous hyper- and hypo-sensitivity: You might be hypersensitive to sound but hyposensitive to temperature, or hypersensitive to visual input but seek tactile stimulation. This isn't contradictory—sensory processing varies by input type.
ADHD seeking meets autism sensitivity:
Your ADHD brain craves stimulation and novelty
Your brain with autism is easily overwhelmed by sensory input
Result: You seek out stimulation (music, movement, fidgeting) but it needs to be specific, controlled stimulation
Too much or the wrong type causes overload
Sensory seeking behaviours:
Fidgeting, spinning, rocking (can be both ADHD restlessness and stimming for regulation)
Need for movement (ADHD) plus preference for specific, repetitive movements (autism)
Listening to the same song repeatedly because it provides the right amount of stimulation without overwhelm
Sensory overwhelm and executive function: This is a critical connection often overlooked: sensory overwhelm depletes executive function.
When you're managing fluorescent lights buzzing, multiple conversations in an open office, uncomfortable clothing, temperature fluctuations, and various smells, your brain is using cognitive resources just to process and filter this input. That leaves less capacity for focusing on tasks, regulating impulses, making decisions, managing time, and regulating emotions.
This is why "just focus harder" doesn't work when you're sensory overwhelmed. Your brain's processing capacity is already maxed out.
Sensory Overload: Shutdown and Meltdown
When sensory (or emotional) input exceeds your processing capacity, you might experience:
Withdrawal and inability to communicate
Need to escape or hide
Going non-verbal or minimally verbal
Feeling disconnected or "foggy"
Needing extended recovery time alone
Loss of behavioural control
Intense emotional expression (crying, shouting)
Physical agitation
Sense of panic or fight-flight-freeze response
Not a tantrum (which is goal-directed) but genuine overwhelm
Both require specific recovery conditions: removing sensory input, safe quiet space, time without demands, and predictable routine to re-regulate.
Sensory Processing and Daily Life
Understanding your sensory profile is crucial for creating environments that work for your brain:
At Work:
Noise-cancelling headphones
Dimmer lighting or desk lamp instead of fluorescent
Flexible clothing policies
Remote work options when possible
Quiet spaces for breaks
At Home:
Controlling lighting (dimmer switches, specific bulbs)
Comfortable clothing options
Sensory-friendly spaces for recovery
Reduced clutter if visual input is overwhelming
In Social Situations:
Limiting exposure duration
Choosing quieter venues
Permission to step away when overwhelmed
Communicating needs to friends/family
Self-Regulation Tools:
Fidget toys or specific textures for sensory seeking
Noise-cancelling headphones or earplugs
Sunglasses or hat for light sensitivity
Weighted blankets or compression clothing for deep pressure
Stim toys (stress balls, textured objects, spinners)
Many people with both conditions describe their sensory needs as "high maintenance", but this is about working with your neurology, not being difficult. When your sensory needs are met, you have more capacity for everything else.
Co-occurring Conditions: Understanding the Full Picture
When we talk about ADHD and autism, we need to acknowledge a crucial reality: approximately 70% of people with these conditions have at least one additional diagnosis.
This isn't coincidental. The same neurological differences that create ADHD and autism also increase vulnerability to other conditions, and the challenges of living in a world not designed for neurodivergent brains create additional stress and mental health impacts.
The Most Common Co-occurring Conditions
Generalised anxiety disorder
Social anxiety disorder
Specific phobias
Panic disorder
Why so common?
Autism: constant social uncertainty, sensory unpredictability, cognitive load of masking.
ADHD: executive function challenges creating perpetual "behind" feeling, fear of forgetting things. Combined: amplified by both.
Insomnia (difficulty falling or staying asleep)
Delayed sleep phase disorder
Irregular sleep-wake rhythms
Sleep apnoea
Why so common?
Autism: sensory sensitivities affecting comfort, routine disruptions. Both: atypical melatonin regulation.
ADHD: difficulty "turning off" racing thoughts.
Mood Disorders:
Depression (major depressive disorder, persistent depressive disorder)
Bipolar disorder (higher rates than general population)
Other Common Co-occurrences:
Dyslexia and other learning disabilities
Developmental coordination disorder (DCD/dyspraxia)
Tourette syndrome or tic disorders
Obsessive-compulsive disorder (OCD)
Eating disorders (particularly in females with autism)
Why This Matters
For Diagnosis: Sometimes these co-occurring conditions are diagnosed first, and ADHD/autism are missed entirely. Someone might be treated for anxiety or depression for years without recognising the underlying neurodevelopmental conditions.
For Treatment: Addressing only ADHD and autism without treating co-occurring conditions often isn't sufficient. Conversely, treating anxiety or depression without recognising ADHD/autism means missing critical context. Comprehensive care needs to address the full picture.
For Self-Understanding: Knowing that co-occurring conditions are the norm, not the exception, helps reduce feelings of being "more broken" than others with ADHD or autism. You're not unusually complicated—this pattern is well-documented.
The Science Behind the Overlap: Why Do ADHD and Autism Co-occur?
Understanding why ADHD and autism so frequently overlap requires looking at the neuroscience—the genetics, brain structure, and neural pathways that create both conditions.
Shared Genetic Architecture
Both ADHD and autism are highly heritable neurodevelopmental conditions:
ADHD heritability: Approximately 70–80%
Autism heritability: Approximately 80–90%
This means genetics account for a large portion of risk for both conditions. But here's what's crucial: the genetic factors overlap.
Large-scale genome-wide association studies (GWAS) have found a genetic correlation between ADHD and autism of approximately rg = 0.3–0.4. This indicates substantial shared polygenic risk, meaning that many common genetic variants contributing to one condition also contribute to the other, albeit with important condition-specific difference
This isn't a complete overlap (the correlation isn't 1.0), so there are many genetic factors unique to each condition. But the shared genetic liability explains why:
Both conditions cluster in families
Having one increases risk for the other
They so commonly co-occur in individuals
The genetic architecture of both is highly polygenic—meaning hundreds of common genetic variants of small effect contribute to risk, along with rarer variants of larger effect.
Specific genetic findings include:
Copy number variants (CNVs): Large deletions or duplications of DNA segments—are associated with increased risk for both ADHD and autism
Genes affecting early brain development and synaptic function contribute to both
Genes related to neurotransmitter systems show overlap
Research shows that individuals diagnosed with both ADHD and autism carry particularly elevated genetic risk for both disorders—essentially an additive genetic burden.
Brain Function: Overlapping and Distinct Networks
Functional brain imaging reveals how neural circuits operate differently:
Shared Patterns: Both ADHD and autism show reduced activation in the middle frontal gyrus (executive control), insula (salience processing), and certain attention networks. This reflects common deficits in attentional control and executive function.
ADHD-Specific Patterns:
Reduced activation in globus pallidus (impulse control)
Greater amygdala reactivity (emotion/impulsivity)
Underactivity in reward processing circuits
Difficulty suppressing the default mode network during tasks (leading to mind-wandering)
Autism-Specific Patterns:
Differences in temporal lobe regions (social perception, language)
Atypical frontal activation during social tasks
Different connectivity in "social brain" networks
Distinct patterns in how networks communicate
Network Connectivity: Modern neuroscience increasingly understands both ADHD and autism as conditions involving atypical patterns of brain network connectivity — differences in how distributed brain regions communicate with one another, rather than damage to a single brain area.
ADHD: In ADHD, studies commonly identify altered and less consistent connectivity within and between executive control and attention networks. Differences are also observed in frontostriatal reward circuitry, which plays a key role in motivation and reinforcement. Together, these patterns are thought to contribute to difficulties with sustained attention, planning, impulse regulation, and motivation, particularly in environments that offer limited immediate reward.
Autism: Autism is associated with atypical connectivity across social cognition and sensory processing networks, alongside differences in the organisation of the default mode network — a system involved in self-referential thought and internally directed attention. Some connections may be unusually strong, while others are weaker, and these patterns can shift over development and across situations — reflecting the wide range of autistic experiences..
A fascinating finding: Children with stronger connectivity between specific frontoparietal and default mode network nodes showed more severe symptoms associated with autism regardless of whether they had autism or ADHD diagnosis. This suggests certain neural circuit patterns specifically underpin difficulties related to autism.
Neurochemistry: Different Systems
ADHD:
Primary dysregulation: Dopamine and noradrenaline
Particularly in fronto-striatal circuits
This explains why stimulant medications (which increase dopamine/noradrenaline) are effective
Autism:
More heterogeneous neurochemical profile
Serotonin (elevated in ~25% of people with autism)
GABA and glutamate (excitatory/inhibitory balance theories)
Oxytocin/vasopressin (social bonding hormones)
No single "deficit" like dopamine in ADHD
There's some overlap—both may involve dopamine system differences—but the primary neurochemical stories are distinct.
What This Means
The neuroscience reveals that ADHD and autism:
Share genetic risk factors (explaining family clustering and co-occurrence)
Show overlapping brain network dysfunction (explaining shared executive function challenges)
Have distinct primary patterns (explaining unique symptoms of each)
When co-occurring, reflect intersection of both patterns (explaining the complexity)
This isn't about one condition causing the other, or one being "worse" than the other. They're two distinct but overlapping patterns of neurodevelopment that can and do co-occur because of shared biological pathways.
Why ADHD and Autism Are Often Missed Until Adulthood
Many adults reach their thirties, forties, or beyond before discovering they have ADHD, autism, or both. They've spent years, sometimes decades, wondering why things feel harder than they should, sensing something is different but not having words or support to name it.
Here's why ADHD and autism are so often missed until later in life:
Masking and Compensation
From a young age, many people (particularly girls and women) learn to mask their neurodivergent traits:
Copying others' social behaviours
Suppressing impulses or stimming
Over-preparing to compensate for executive function challenges
Learning social scripts to navigate situations
Hiding confusion or difficulty
Masking often works well enough that the struggles go unnoticed by others—even if they're completely exhausting to maintain. You might appear to be functioning fine whilst experiencing constant internal struggle.
Research on camouflaging shows:
People with autism (especially females) develop sophisticated masking strategies
This comes with significant cognitive load
Long-term consequences include mental health deterioration and burnout
Masking ability often predicts later diagnosis (those who mask well are diagnosed later)
The same applies to ADHD—people develop coping mechanisms (extensive to-do lists, reminder systems, hyperfocus on school deadlines) that hide the underlying executive function challenges.
Gender Bias in Diagnosis
Diagnostic criteria have historically been based primarily on how ADHD and autism present in boys, meaning girls, women, and gender-diverse individuals have been systematically missed:
Autism in females:
May develop superficial friendships more easily
Often have strong interest in fiction or animals (considered "normal" interests)
Use social scripts learnt through observation
May be labelled as "shy," "quirky," or "sensitive" instead
Later diagnosed with anxiety, depression, or eating disorders that are actually related to unrecognised autism
ADHD in females:
More likely to have inattentive presentation (daydreamy, disorganised, forgetful)
Less likely to be hyperactive or disruptive
Teachers and parents might not flag them since they're not causing behavioural problems
Diagnosed with anxiety or depression instead
Gender bias in diagnostic criteria is now well-documented, and clinical guidelines emphasise actively looking for ADHD/autism in women and girls who present with suggestive histories.
Structured Environments Hide Executive Function Challenges
School environments often provide external structure that compensates for executive function difficulties:
Regular schedule and routine
Teacher-imposed deadlines
Parent support with organisation
Clear expectations and rules
For many people, ADHD or autism doesn't become obvious until structure falls away:
University: more independent organisation required
First job: managing workload independently
Living alone: executive function demands increase
Parenthood: overwhelming demands with no structure
Life transitions: change exposes rigidity or executive challenges
This is why many adults seek diagnosis after what they call a "life falling apart" moment—when the scaffolding that held things together disappears.
Burnout Prompts Reassessment
Many adults discover neurodivergence after experiencing burnout that doesn't improve with usual interventions, anxiety or depression that doesn't fully respond to treatment, increasing difficulty masking or compensating, or breakdown of coping strategies that eventually become unsustainable.
Misdiagnosis and Diagnostic Overshadowing
Sometimes other conditions are diagnosed first, and the underlying neurodevelopmental conditions are missed:
Anxiety or depression diagnosed without recognising ADHD/autism underneath
Borderline personality disorder misdiagnosis in women with autism
Mood disorders when ADHD emotional dysregulation is the primary issue
Eating disorders related to autism sensory issues or rigidity
Diagnostic overshadowing also happens where one diagnosis masks another: an autism diagnosis leads clinicians to attribute all attention issues to autism (missing ADHD), or an ADHD diagnosis leads to missing subtle social communication differences (autism).
The Role of Intelligence and Achievement
High intelligence can mask both conditions:
Compensating through cognitive ability
Meeting academic or career milestones despite internal struggle
Being dismissed because "you're too successful to have ADHD/autism"
This leads to what many call "twice exceptional"—having both intellectual giftedness and neurodevelopmental conditions, where each masks the other.
Adult Diagnosis Challenges
Evaluating adults who self-refer requires retrospective childhood information (difficult to recall or verify), collateral reports from family (if available), and careful assessment to distinguish late-presenting symptoms from adult-onset conditions.
Some clinicians are overly strict about childhood evidence requirements, excluding deserving adults. Others may over-diagnose without thorough assessment. Balanced, comprehensive evaluation is crucial.
Why Recognition Matters Now
Whether you're discovering this at 25, 45, or 65, recognition matters because:
It provides a framework for understanding your experiences
It opens access to support—accommodations, treatment, community
It reduces shame
It enables self-compassion
It can prevent burnout—by making sustainable choices earlier
Late diagnosis is common, valid, and increasingly recognised by clinicians who understand how neurodivergence can be masked across the lifespan.
Assessment and Finding Support for ASD and ADHD
If you recognise yourself in this article, you might be wondering about next steps. Assessment can provide clarity, validation, and access to support—but it's also a personal decision about what feels right for you.
When to Consider Assessment
Consider seeking professional assessment if:
You identify with patterns across ADHD and/or autism
These patterns significantly impact daily functioning (work, relationships, wellbeing)
You're experiencing burnout, anxiety, or depression related to these challenges
You want formal diagnosis for access to accommodations, medication, or services
You need clarity and validation of your experiences
Assessment isn't mandatory—some people find understanding and community sufficient. Others need formal diagnosis for practical reasons (workplace accommodations, medication access, NDIS support in Australia).
What Comprehensive Assessment Includes
Quality assessment for ADHD and autism (especially when considering both) should include:
Developmental History:
Childhood behaviours and patterns
School performance and social experiences
How symptoms have manifested across lifespan
Family history (both are highly heritable)
Current Functioning:
How symptoms impact daily life currently
Work, relationships, self-care, wellbeing
Coping strategies and masking patterns
Co-occurring conditions (anxiety, depression, sleep)
Standardised Assessments:
Rating scales and questionnaires
For ADHD: measures of attention, impulsivity, executive function
For autism: measures of social communication, repetitive behaviours, sensory processing
Cognitive testing when indicated
Differential Diagnosis: Distinguishing ADHD symptoms from autism symptoms, primary conditions from co-occurring conditions, and what's ADHD/autism versus what's trauma, anxiety, or other factors.
Collateral Information: When possible, input from family members who knew you as a child, partners or close friends, and school records or past assessments.
Clinical Judgement: Experienced assessors understand masking and camouflaging patterns, how ADHD and autism present in adults, gender differences in presentation, and cultural factors in symptom expression.
The Challenge of Differential Diagnosis
Teasing apart ADHD and autism can be clinically complex because:
Overlapping Symptoms:
Both can involve social difficulties (ADHD from impulsivity, autism from communication differences)
Both involve emotional regulation challenges (but for different reasons)
Both can present with sensory sensitivities
Executive function challenges appear in both
Different Underlying Mechanisms: The key is understanding why symptoms occur:
Interrupting: ADHD = racing thoughts; Autism = difficulty with social timing
Deep interests: ADHD = hyperfocus; Autism = enduring, meaningful interests
Social withdrawal: ADHD = understimulation; Autism = overwhelm or preference
Experienced clinicians look for these nuances.
Finding Support That Honours Your Experience
Having both ADHD and autism it's about having a brain that works differently in multiple, overlapping ways. The challenges are real, but so are the strengths: the deep focus, the pattern recognition, the creative thinking, the authentic way of being in the world.
At Kantoko
we understand that seeking assessment for ADHD and autism (particularly when considering both) can feel overwhelming. That's why our approach is:
ADHD-Informed and Autism-Aware: Our clinicians specialise in ADHD treatment and are trained to recognise overlapping traits, understand how both conditions present in adults, and provide thoughtful, comprehensive assessment. When autism is present, we'll continue to manage your ADHD and may refer you to a psychologist for a secondary autism assessment if needed.
Respectful of Neurodiversity:
Recognising that different isn't less than
Supporting you to thrive as your authentic self
Focusing on quality of life, not forcing neurotypical behaviour
Whether you're newly discovering this overlap or finally finding language for what you've always known about yourself, you deserve support that sees and honours your full authentic self.
Ready to take the first step? Get started with us today.
Frequently Asked Questions
Can I have ADHD and Autism?
Yes, absolutely. It’s very common for ADHD and Autism to co-occur, and both are lifelong neurodevelopmental conditions. This overlap is now recognised in both the DSM-5 and ICD-11, allowing for a dual diagnosis when both are present.Many adults only discover this connection later in life, often after years of wondering why things feel harder than they seem for others.
What do Autism and ADHD look like together?
The informal term AuDHD is often used to describe people who identify with both conditions. It can feel like living with conflicting needs. For example, craving novelty and stimulation (often seen in ADHD), while also needing routine, predictability, and downtime (more common in Autism).
Many people with AuDHD also experience:
Emotional intensity and trouble with regulation
Sensory sensitivity mixed with impulsivity
Mental fatigue from masking, switching tasks, or social interaction
The combination can be exhausting—but with the right understanding and support, things get easier.
What is the 10–3 Rule for ADHD?
This is a gentle technique that can help with task initiation, especially when you’re feeling stuck. The idea is to set a timer for just 10 minutes, give yourself full permission to stop after that, and then check in with yourself.
If 10 minutes still feels too hard, aim for just 3. Sometimes just starting (even for a few minutes) helps overcome that initial mental resistance.
Is it ADHD or AuDHD?
This is a question many people ask, especially if they’ve been diagnosed with ADHD but still feel like something’s missing.
While ADHD vs Autism involves different diagnostic criteria, they can absolutely overlap. The most important step is to look at your full experience, not just symptoms in isolation. That’s where a comprehensive assessment can make all the difference in getting the support you need that fits who you are.
This article is for informational purposes only and is not a substitute for professional medical advice. Always consult a qualified healthcare provider for diagnosis and treatment options.