ADHD vs Autism vs PDA

ADHD vs Autism vs PDA describes a classroom distinction that is easy to miss: attention regulation, autistic processing differences and anxiety-driven demand avoidance can look similar during the same lesson. A Year 4 learner stares out of the window during carpet time, fidgets, interrupts and avoids writing.

The teacher suspects ADHD. The SENCO also notices distress at unstructured break times and changes to routine, which points towards autism. At home, his parents describe extreme demand avoidance and distraction around everyday tasks, so PDA enters the picture.

ADHD vs Autism vs PDA compares three profiles that can look similar in class. ADHD mainly affects attention, inhibition and executive function. Autism affects social communication, sensory processing and the need for predictability.

PDA describes extreme demand avoidance linked to a felt loss of autonomy. It is usually discussed as a profile within autism, rather than as a separate formal diagnosis (Green et al., 2018; Kildahl et al., 2021).

This scenario plays out in UK classrooms every week. ADHD, autism and PDA are not neat boxes: the DSM-5 allowed dual ADHD-autism diagnoses, and PDA is still debated rather than recognised as a separate DSM-5-TR or ICD-11 category (American Psychiatric Association, 2013; Green et al., 2018; Kildahl et al., 2021).

Teachers observe behaviours, but the same behaviour can have different causes. A learner who "can't sit still" may have ADHD, autism, or both. A learner who refuses tasks may be protecting themselves from overload, anxiety, loss of autonomy, or an unidentified learning difficulty.

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Why Conditions Overlap

Neurodevelopmental profiles overlap because attention, sensory processing, emotional regulation and executive function are linked. Differences in prefrontal development can affect inhibition, working memory and impulse control. Sensory load can also push a learner into shutdown or distress (Kern et al., 2015). In class, the same refusal to start writing may reflect ADHD task initiation, autistic overload, a PDA profile, or a specific learning difficulty.

The DSM-5 removed the diagnostic exclusion that previously prevented dual ADHD-autism diagnoses (American Psychiatric Association, 2013). For more on this topic, see Conners rating scale teachers guide. This change acknowledged what teachers had long observed: ADHD and autism often co-occur rather than appearing as tidy, separate profiles. A meta-analysis by Rommelse et al. (2010) found shared genetic factors between ADHD and ASD, with siblings of autistic children showing higher ADHD traits than the population average.

For SENCOs, this clustering creates a practical problem: referral pathways are usually condition-specific, but classroom need is not. A CAMHS referral for ADHD follows one route, an autism assessment follows another, and demand avoidance often starts a third conversation; waiting for the perfect label leaves teachers managing distress without a plan. A transdiagnostic approach means tracking attention, sensory load, flexibility, autonomy and emotional recovery across labels, then putting low-arousal, high-flexibility support in place while referral evidence is gathered (Astle et al., 2022). The Symptom Overlap Matrix below helps you map what you observe before deciding where to refer.

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The Five Conditions at a Glance

When SENCOs understand the main features of each condition, they can tell similar classroom needs apart more clearly. Use it as a starting point for professional discussion: identify the learner's current need, record evidence from more than one lesson, and agree the next classroom adjustment with the SENCO or family.

Learners with a PDA profile often use charm, distraction, delay or excuses to avoid tasks (Newson et al., 2003; O'Nions et al., 2014). The key issue is not ordinary refusal, but a threat response when a demand feels like loss of autonomy. PDA is not a separate DSM-5-TR or ICD-11 diagnosis; it is usually discussed as a demand-avoidant profile within autism, although this classification remains disputed (Green et al., 2018; Kildahl et al., 2021). Some neurodiversity-affirming writers prefer terms such as Pervasive Drive for Autonomy or Rational Demand Avoidance because these name the need for control without labelling the learner as wilfully difficult (Milton and Woods, 2018).

Letter reversals alone do not diagnose a learning difficulty. However, ongoing barriers with reading, spelling or writing need careful assessment (Elliott & Grigorenko, 2014; Fawcett & Nicolson, 2007; Shaywitz & Shaywitz, 2005). Check whether the learner also has working memory, phonological processing or fluency difficulties (Alloway, 2009; Gathercole & Alloway, 2008). A literacy barrier can look like task refusal when the work feels exposing.

Condition	Core Feature	What You See in the Classroom
Autism (ASD)	Differences in social communication and restricted/repetitive patterns	Misses social cues, prefers routine, intense topic focus, sensory sensitivity, literal interpretation of language
ADHD	Persistent inattention, hyperactivity, and impulsivity	Fidgets, blurts out answers, loses equipment, struggles with sustained focus, seeks novelty
PDA Profile	Extreme avoidance of everyday demands driven by anxiety
ODD	Pattern of angry/irritable mood, argumentative behaviour, vindictiveness	Deliberately annoys others, refuses adult requests, blames others, loses temper frequently
SpLD	Specific difficulties with reading, writing, maths, or motor coordination

This complexity means teachers should look for patterns across categories, not search for a single neat cause. A learner may show attention differences, sensory distress and demand avoidance in the same week. Recording the trigger, setting, recovery time and successful adjustment gives a stronger picture of need than a label-only checklist.

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Where Symptoms Overlap: The Six Domains

Observable classroom behaviour can hide different causes. The six domains below separate what the teacher sees from what may be driving it, so a learner is not misread as careless, defiant or lazy when the barrier is attention, sensory load, anxiety or literacy access (Hinshaw, 2002; Barkley, 2006).

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Social Communication

Social difficulties appear across multiple conditions, but the underlying mechanism differs. An autistic child may struggle to read facial expressions because of differences in social cognition (Baron-Cohen, 1997). A child with ADHD may miss social cues because they were not attending when the cue occurred. A child with a PDA profile may appear socially skilled in one-to-one interactions but struggle in group settings where demands increase.

What the teacher sees: A learner who talks over others during group work, stands too close to peers, or gives responses that seem unrelated to the conversation topic. All three conditions produce this behaviour, but the cause is different each time.

Observe if the learner's social struggles are constant (ASD) or shift with interest and arousal (ADHD). If the learner skillfully avoids work but finds real friendships hard, think PDA.

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Attention and Focus

Inattention is common across conditions, says Barkley (1990). Autistic learners may seem inattentive in class but focus intensely on interests. Learners with SpLD may "zone out" when reading, explains Nicolson (2009). Decoding uses so much effort they cannot comprehend, notes Fawcett (1996).

What the teacher sees: A learner who stares out the window during teacher exposition but produces detailed artwork during free choice time.

Map the inattention pattern. Check for SpLD first if reading/writing tasks are hardest. ADHD is likelier if novelty improves attention across contexts. Autism fits better if the learner's attention is intensely narrow (Barkley, 2015).

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Emotional Regulation

Meltdowns, shutdowns, and emotional outbursts occur across ASD, ADHD, PDA, and ODD. The trigger and recovery pattern differ.

Autistic meltdowns often start with sensory overload or change (Mazefsky et al., 2013). Verbal calming may not work during this intense crisis.

ADHD learners' outbursts are often quick, from frustration, and soon pass. PDA distress rises when faced with demands, seeming like panic. ODD defiance targets adults and lasts longer.

What the teacher sees: A child who throws a chair during a maths lesson.

How to distinguish: Ask three questions: (1) Was there a sensory or routine trigger? (ASD) (2) Was the child asked to do something? (PDA) (3) Is this behaviour targeted at a specific adult and sustained? (ODD) (4) Did it resolve within minutes once the frustration passed? (ADHD)

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Sensory Processing

Sensory processing differences are part of the autism diagnostic criteria (DSM-5). However, sensory distress also appears in ADHD, DCD/dyspraxia and PDA profiles (Ghanizadeh, 2011). A learner who covers their ears during alarms may be responding to auditory pain, loss of predictability, crowding, or a demand linked to the noise. Record the sensory trigger before treating the behaviour as non-compliance.

What the teacher sees: A learner who refuses to wear the school jumper, complains about classroom lighting, or becomes distressed in the dinner hall.

Researchers explain sensory difficulties in different ways. If the difficulty stays the same across places and is clearly linked to sound, touch, light or other senses, it may indicate ASD (Mazefsky et al., 2013). If the sensory issue changes with the learner's emotions, it could be ADHD (Ghanizadeh, 2011). If complaints increase when adults make demands, such as "wear your jumper", this may suggest demand avoidance.

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Executive Function

Brown et al. (2017) found that executive function includes planning and organisation. Learners also need task initiation, working memory, and cognitive flexibility. Diamond (2013) notes that similar symptoms can appear in different situations. Goldstein et al. (2018) highlight significant overlap.

Barkley (2012) says ADHD affects inhibition, which means stopping an impulse, and working memory. Hill (2004) found that autistic learners can find cognitive flexibility, or shifting thinking, hard. PDA learners use executive functions when they lead the learning. For SpLD learners, executive function problems often come from managing learning needs.

These behaviours can point to different barriers. Some learners struggle to plan, organise materials or hold instructions in working memory; others can plan well when they choose the task but freeze when an adult imposes it (Meltzer, 2007; Levine, 2002; Diamond, 2013). Note whether support works better as a checklist, a model, a sensory adjustment or a choice-based invitation.

Consider PDA if a learner plans their own tasks well, but struggles with your activities. Check for SpLD if literacy/numeracy shows the biggest executive function problems. ADHD or ASD are possible if difficulties are widespread (Gillberg, 1992; Baron-Cohen, 1988).

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Learning and Academic Performance

Neurodevelopmental profiles can affect learning unevenly. A bright autistic learner may meet academic targets but still struggle with the classroom environment. A learner with dyslexia may show behaviour difficulties because reading or writing in front of others has become a public risk (Ford et al., 2003).

These discrepancies have been observed by researchers (e.g., Ganschow et al., 1992; Shaywitz, 1998). Teachers may see a learner whose writing is much weaker than their speaking. Alternatively, a learner may do well on tests yet avoid doing work in class.

Compare test scores with classroom work to spot differences. A large gap between verbal skills and writing may indicate SpLD. Learners who refuse tasks despite ability may have PDA (Newson et al., 2003). If performance differs day to day, consider ADHD (Antshel, 2018).

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Using the Symptom Overlap Matrix

The interactive tool below allows you to select two or three conditions and compare their overlapping symptoms across all six domains. Select the conditions you are considering for a specific learner, and the matrix will highlight which symptoms are shared and which are unique to each condition.

The matrix helps record your Assess-Plan-Do-Review cycle; download the PDF. This PDF gives a clear record of observations. This record assists referrals to educational psychology or CAMHS.

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How a SENCO Would Use This

Observe first. Spend two weeks gathering structured observations across the six domains above, noting frequency and context.

Select conditions. Based on your observations, select the two or three conditions that best match what you are seeing.

Compare overlaps. The matrix shows you which behaviours are shared and which are unique. Shared symptoms alone cannot distinguish conditions; unique symptoms are your diagnostic anchors.

Read the differentiationion guidance. For each shared symptom, the "How to tell the difference" panel explains what to look for in the classroom.

Document and refer. Download the PDF and attach it to your referral documentation. This structured evidence demonstrates that school-level assessment has been thorough.

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The Graduated Approach: From Observation to Referral

The SEND Code of Practice (DfE, 2015) requires schools to follow a Graduated Approach before seeking external assessment. The symptom overlap framework fits directly into this cycle. Use it as a starting point for professional discussion: identify the learner's current need, record evidence from more than one lesson, and agree the next classroom adjustment with the SENCO or family.

APDR Stage	What You Do	Tool to Use
Assess	Structured classroom observation across 6 domains for 2-4 weeks	Symptom Overlap Matrix (above)
Plan	Identify likely conditions and plan targeted classroom adjustments	Differentiation guidance from the matrix, condition-specific strategy cards
Do	Implement adjustments for 6-8 weeks, tracking frequency and intensity of target behaviours	Behaviour tracking sheets, ABC charts
Review	Compare pre- and post-intervention data; decide whether to continue, adjust, or escalate	Symptom Overlap Matrix re-assessment + PDF comparison

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When to Seek External Assessment

Refer to educational psychology or CAMHS when:

• Classroom adjustments have been implemented for at least one APDR cycle (6-8 weeks minimum) without measurable improvement
• The child's presentation crosses multiple domains with significant intensity in each
• The child's difficulties are affecting their access to the curriculum despite Quality First Teaching
• Parents report similar patterns at home, suggesting the difficulties are pervasive rather than context-specific
• You suspect co-occurring conditions (for example, ADHD and autism together) that require specialist differential assessment

The Matrix assessment data helps with learner referrals. Educational psychologists value structured data because it can support faster assessments (Frederickson & Cline, 2015). This strengthens your case when you work with external agencies.

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Masking and Gender Differences

Symptom overlap becomes even more complex when masking is considered. Autistic girls are diagnosed on average 1.8 years later than autistic boys (Begeer et al., 2013), partly because they learn to copy the social behaviours of neurotypical peers. A girl who appears socially competent in class but experiences daily meltdowns at home may be masking her autism. If the SENCO only observes school behaviour, the presentation may look like anxiety or, in some cases, ODD.

ADHD in girls often differs from typical hyperactive boys. Girls often show inattention, like daydreaming, rather than acting out (Hinshaw et al., 2022). Teachers may miss this until secondary school. Academic pressures increase and coping strategies stop working.

The matrix helps compare a learner's school and home behaviours. A big difference between settings can suggest masking (Attwood, 2006; Lai et al., 2017). This discrepancy can provide key insight (Gould & Ashton-Smith, 2011; Gillberg et al., 2014).

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Practical Next Steps for Your School

This week: Choose one learner whose presentation puzzles you. Use the Symptom Overlap Matrix to compare the two or three conditions you suspect. Download the PDF and file it in the learner's SEND record.

This half-term: Share the matrix with your teaching staff during a SEND twilight session. Walk through the six domains and discuss how to distinguish overlapping presentations using the "how to tell the difference" guidance.

This term: Audit your current SEND register. For learners with a single identified need, check whether their classroom presentation suggests co-occurring conditions that may have been overlooked. The SEND Code of Practice encourages schools to review and update assessments as new information emerges.

The conditions in this article are not separate boxes; they are overlapping spectra, so learners need professionals who can make sense of complex classroom patterns. Since the pandemic, schools also need to tell neurodevelopmental demand avoidance apart from EBSA, school distress, masking exhaustion and neurodivergent burnout; attendance data alone will not show which barrier is operating (Connolly et al., 2023). Vygotsky (1978) supports guided social learning, and Karpicke (2008) shows why retrieval strengthens memory, but direct prompting, public questioning or timed quizzes can feel like demands to some neurodivergent learners. The Symptom Overlap Matrix gives a clear framework for moving from "I think this is ADHD" to "here is the systematic evidence for what I observe, and here is what distinguishes it from the alternatives."

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Frequently Asked Questions

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Limitations and Critiques

The main limit is diagnostic certainty. PDA is not a separate diagnostic category in DSM-5-TR or ICD-11. Green et al. (2018) describe it as symptoms rather than a syndrome. Kildahl et al. (2021) reviewed the child and adolescent evidence and found small, mixed-method studies, heavy reliance on parent report, circular definitions based on Newson's original criteria, and limited attention to other explanations such as anxiety, trauma or sensory overload.

A second critique focuses on language and power. Milton and Woods (2018) argue that "pathological" can present autistic resistance, masking and self-advocacy as disorder. These behaviours may instead be responses to demands that feel unsafe.

This matters culturally because the same classroom behaviour may be read differently by race, gender, social class and parental confidence. Research on autism and ADHD identification shows persistent inequities in who receives protective developmental explanations and who receives punitive behaviour labels (Mandell et al., 2009; Morgan et al., 2013).

Broad learning theory also has limits: Vygotsky (1978) helps teachers plan social scaffolding, and Karpicke (2008) supports retrieval practice. However, neither framework was built around sensory overload, demand avoidance or neurodivergent burnout. If schools use prompts, public questioning and repeated recall too rigidly, they can increase threat rather than learning. This comparison still has practical value: it helps schools replace blame with observation and adapt support while staying honest about diagnostic uncertainty.

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References

Karpicke, J. (2008). The critical importance of retrieval for learning.

Vygotsky, L. (1978). Mind in society: The development of higher psychological processes.

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Further Reading: Key Research Papers

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Try the Symptom Overlap Matrix

Use this free, interactive tool to compare overlapping traits across ADHD, autism, PDA, ODD, and specific learning difficulties. No learner data is stored. Use it as a starting point for professional discussion: identify the learner's current need, record evidence from more than one lesson, and agree the next classroom adjustment with the SENCO or family.