Moderate Evidence

Lookalikes

Conditions and situations that can mimic autism or ADHD. Understanding these helps ensure accurate diagnosis and appropriate support.

Why understanding lookalikes matters

Many conditions share surface-level symptoms with autism and ADHD
Misdiagnosis can lead to ineffective or harmful interventions
Understanding the root cause guides appropriate support
Some "lookalikes" may co-occur with neurodevelopmental conditions
Environmental factors can create symptoms that resolve when addressed

Anxiety disorders

Can look like: Autism, ADHD

Shared features

•Difficulty concentrating
•Social avoidance
•Rigidity and need for routines
•Restlessness and fidgeting
•Sleep difficulties
•Emotional dysregulation
•School refusal

Key differences

Onset: Anxiety can develop at any age; autism/ADHD are present from early childhood

Fear-driven: Anxiety behaviours are motivated by fear; autism/ADHD by different mechanisms

Response to reassurance: Anxiety may temporarily improve with reassurance; autism traits don't

Variability: Anxiety symptoms fluctuate with stress; autism traits are more consistent

Important: Anxiety is also very common IN autism and ADHD. Both can be present.

Trauma / PTSD / Complex trauma

Can look like: Autism, ADHD

Shared features

•Hypervigilance (can look like hyperactivity)
•Difficulty concentrating
•Emotional dysregulation
•Social difficulties
•Sleep problems
•Sensory sensitivities
•Avoidance behaviours

Key differences

Timeline: Trauma symptoms follow adverse experience; autism/ADHD are developmental

Triggers: Trauma responses are triggered by reminders; autism/ADHD traits are more global

Flashbacks/nightmares: Specific to trauma, not present in autism/ADHD alone

Response to safety: Trauma symptoms reduce when child feels safe; autism/ADHD traits persist

Important: Neurodivergent children are MORE vulnerable to trauma. Both can be present.

Sleep deprivation / Sleep disorders

Can look like: ADHD (primarily)

Shared features

•Difficulty concentrating
•Hyperactivity (paradoxical response in children)
•Irritability and emotional dysregulation
•Impulsivity
•Memory problems
•Poor academic performance

Key differences

Resolves with sleep: Sleep-related symptoms improve when sleep is addressed

Variability: Symptoms worse after poor sleep nights; ADHD is more consistent

Sleep history: Identifiable sleep problem (apnoea, restless legs, insomnia)

Physical signs: Dark circles, difficulty waking, excessive daytime sleepiness

Important: Sleep problems are also common IN ADHD. Addressing sleep first is often recommended.

Giftedness (high cognitive ability)

Can look like: Autism, ADHD

Shared features

•Intense focus on interests
•Preference for adult company
•Boredom with routine tasks
•Asynchronous development
•Sensitivity (emotional and sometimes sensory)
•Difficulty with peers
•High energy and curiosity

Key differences

Social motivation: Gifted children typically understand social rules; just prefer intellectual stimulation

Flexibility: Gifted children can usually adapt when motivated; autism shows persistent rigidity

Communication: Gifted children have strong communication; autism affects social communication

Challenge-seeking: Gifted children engage with difficult material; ADHD struggle persists regardless of interest

Important: Giftedness can co-occur with autism/ADHD ("twice exceptional" or 2e). Both can be present.

Other conditions to consider

Hearing impairment

Can look like: Autism, ADHD (inattention)

May not respond to name, appear inattentive, have delayed language

Rule out: Hearing test is essential before autism/ADHD assessment

Vision problems

Can look like: ADHD, learning difficulties

May avoid reading, appear distracted, have headaches

Rule out: Vision screening including near vision

Iron deficiency anaemia

Can look like: ADHD

Fatigue, poor concentration, restlessness, irritability

Rule out: Blood test for ferritin and full blood count

Thyroid disorders

Can look like: ADHD, mood disorders

Hyperactivity or lethargy, concentration problems, mood changes

Rule out: Thyroid function tests

Absence seizures

Can look like: ADHD (inattention)

Brief "zoning out," appears to not hear, inconsistent attention

Rule out: EEG if suspected; episodes are brief and have specific characteristics

Language disorders

Can look like: Autism

Communication difficulties, may avoid social situations due to language struggles

Rule out: Speech and language assessment

Attachment difficulties

Can look like: Autism

Social difficulties, regulation problems, unusual social behaviours

Rule out: Detailed early history; pattern of attachment behaviours

Foetal alcohol spectrum disorder (FASD)

Can look like: ADHD, autism

Executive function difficulties, social problems, attention issues

Rule out: Prenatal alcohol exposure history; facial features may be present

Environmental factors

Sometimes environmental factors create symptoms that can be mistaken for neurodevelopmental conditions.

Bullying

Can cause anxiety, social withdrawal, school refusal that looks like autism/ADHD

Symptoms often started or worsened after bullying began

Family stress / parental conflict

Can cause concentration problems, hypervigilance, emotional dysregulation

Symptoms may improve when home environment stabilises

Academic pressure

Can cause anxiety, avoidance, concentration difficulties

Symptoms may be worse around exams/homework, better in holidays

Screen overuse

Can affect attention, sleep, emotional regulation

Trial of reduced screen time may show improvement

Poor diet / dehydration

Can affect concentration, energy, mood

Symptoms improve with basic nutrition and hydration

When both are present

"Lookalike" conditions often co-occur with neurodevelopmental conditions.

Autism + anxiety

Anxiety is extremely common in autism. Both need addressing.

Autism accommodations can reduce anxiety. May also need anxiety-specific support.

ADHD + sleep problems

ADHD commonly disrupts sleep. Sleep deprivation worsens ADHD.

Address sleep first where possible. May still need ADHD treatment.

Neurodivergence + trauma

Neurodivergent children are more vulnerable to trauma.

Trauma-informed approach alongside neurodevelopmental support.

Giftedness + autism/ADHD (2e)

Can co-occur. Giftedness can mask or complicate presentation.

Need both intellectual challenge and neurodevelopmental support.

Important to know:

Red flags that suggest a "lookalike" rather than autism/ADHD:

Symptoms appeared suddenly after a specific event or change
Presentation is very different at home vs school (consider masking)
Symptoms resolve completely in certain environments
No evidence of traits in early childhood
Child explicitly describes fear or worry as the driver
Known adverse experiences or environmental stressors

Note: These don't rule out autism/ADHD - they suggest further investigation is needed. Professional assessment is essential.

The key insight

Surface-level symptoms don't tell the whole story. Many conditions can look like autism or ADHD on the surface. Understanding the underlying cause - developmental difference, anxiety, trauma, sleep, or environmental factors - is essential for providing the right support. And importantly, these aren't always either/or. A child can have autism AND anxiety, ADHD AND sleep problems. Good assessment considers all possibilities.

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Differential Patterns Autism + ADHD What to Expect in Assessment