Neurodevelopmental Disorders I: Autism Spectrum Disorder and Intellectual Disability

MKU MBChB Year 4 · Junior Clerkship · Week 6 · Clinical revision notes

Learning objectives

By the end of this topic, you should be able to:

• Define neurodevelopmental disorders and distinguish autism spectrum disorder (ASD) from intellectual disability (ID).
• Recognise the core clinical features and developmental red flags.
• Take a focused developmental history and identify information needed from caregivers, school and other informants.
• Outline assessment, common differentials, comorbidities and multidisciplinary management.
• Apply the principles to a short clinical case.

1. What are neurodevelopmental disorders?

Neurodevelopmental disorders begin during the developmental period and affect personal, social, academic or occupational functioning. Examples include ASD, intellectual disability, attention-deficit/hyperactivity disorder (ADHD), specific learning disorders, communication disorders and motor disorders.

Clinical principle: identify the child's developmental profile and functional needs; do not diagnose from one behaviour or one screening score alone.

2. Autism spectrum disorder (ASD)

Definition

ASD is a neurodevelopmental condition characterised by persistent difficulties in social communication and social interaction, together with restricted or repetitive patterns of behaviour, interests or activities. Features begin in the developmental period and cause clinically significant functional impact. Presentation varies widely between individuals.

Core diagnostic domains

A. Social communication and interaction — difficulties across contexts, for example:

• Reduced social-emotional reciprocity: limited back-and-forth interaction, sharing of interests or response to social approaches.
• Differences in non-verbal communication: eye contact, facial expression, gestures or integration of verbal and non-verbal cues.
• Difficulty developing, maintaining or understanding relationships; difficulty adapting behaviour to different social contexts or engaging in imaginative peer play.

B. Restricted or repetitive behaviour/interests — at least two types are required under DSM-5-TR:

• Repetitive movements, use of objects or speech (e.g. hand-flapping, lining up objects, repeated phrases).
• Insistence on sameness, routines or ritualised patterns; marked distress with change.
• Highly restricted or unusually intense interests.
• Hyper- or hypo-reactivity to sensory input, or unusual sensory interests (e.g. strong response to sounds, textures, lights or pain).

Symptoms must be present in the early developmental period, although they may become more apparent when social demands increase. They must cause significant impairment and not be better explained solely by intellectual disability or global developmental delay.

Important clinical points

• ASD is a spectrum: language, intellectual ability, sensory profile and support needs differ substantially.
• Delayed speech alone does not establish ASD; assess social communication, play, gestures, reciprocity and repetitive/sensory behaviours.
• A child may show affection and may make eye contact; neither finding alone rules ASD in or out.
• Do not blame parenting. ASD is a neurodevelopmental condition with complex genetic and biological contributions.
• Girls and children with fluent language can be missed when difficulties are subtle or masked.

Developmental red flags

Seek developmental assessment when there is:

• Loss of previously acquired language, social or motor skills (regression).
• Limited response to name, reduced shared attention or little pointing/showing to share interest.
• Few gestures, limited reciprocal interaction or absent pretend play for developmental age.
• Persistent repetitive behaviours, very restricted interests or marked distress with routine changes.
• Language or social difficulties that interfere with participation at home, school or with peers.

Regression warrants prompt medical and developmental evaluation; do not assume it is simply autism.

3. Intellectual disability (ID)

Definition

Intellectual disability involves deficits in both:

1. Intellectual functioning — reasoning, problem-solving, planning, abstract thinking, judgement, academic learning and learning from experience.
2. Adaptive functioning — how independently and responsibly a person meets age- and culture-expected standards in conceptual, social and practical daily life.

Onset is during the developmental period. Assessment should combine clinical evaluation, developmental history, standardised testing where available and information from people who know the child. An IQ score alone is not sufficient to describe the person's support needs.

Adaptive functioning examples

• Conceptual: language, literacy, numeracy, time, money and self-direction.
• Social: interpersonal communication, understanding social cues, judgement and awareness of risk.
• Practical: personal care, routines, safety, household tasks, school/work and community participation.

DSM-5-TR severity is based primarily on adaptive functioning, not IQ alone. Support needs can differ across domains and environments.

Causes and associated factors

Potential causes include genetic/chromosomal conditions, congenital brain abnormalities, prenatal exposures or infections, prematurity or perinatal complications, severe early malnutrition, central nervous system infections, traumatic brain injury and some metabolic disorders. In some children, the cause remains unknown.

A cause should not be assumed from appearance alone. Look for treatable contributors such as hearing or visual impairment, seizures, thyroid/metabolic disease, nutritional problems or environmental barriers.

4. ASD versus intellectual disability

• ASD primarily requires the specific social-communication pattern and restricted/repetitive behaviours.
• ID requires deficits in intellectual functioning and adaptive functioning.
• They can co-occur. To diagnose ASD in a person with ID, social communication must be below what would be expected for the person's general developmental level.
• A child with language delay may have hearing impairment, a language disorder, global developmental delay/ID, ASD or more than one condition. History and assessment distinguish them.

5. Focused developmental history

Ask the caregiver in a non-judgemental way, and obtain school or other collateral information with appropriate consent.

Pregnancy and birth: antenatal illness/infections, medicines or exposures, gestational age, birth complications, neonatal admission and milestones after birth.

Developmental trajectory: when the child sat, walked, babbled, spoke first words and combined words; gestures, pointing, response to name, pretend play and peer interaction. Ask specifically whether any skills were lost.

Communication and social interaction: understanding and use of language, back-and-forth interaction, sharing enjoyment, non-verbal communication, friendships and play.

Behaviour and sensory profile: routines, repetitive movements or speech, focused interests, responses to sound/touch/food, sleep, feeding, distress and triggers.

Function: self-care, school progress, daily living skills, safety, participation and level of support needed.

Medical and family history: seizures, hearing/vision concerns, sleep, feeding, regression, chronic illness, family history of developmental conditions and current medicines.

Context: caregiver concerns, strengths, languages used at home, cultural context, access to education and services, and family support. Avoid interpreting multilingual exposure itself as a disorder.

6. Assessment: a practical clinical approach

1. Clarify the concern and timeline. What prompted assessment, when did it begin, and is there regression?
2. Review development and functioning across home, school and community; seek collateral information.
3. Observe the child in age-appropriate interaction: shared attention, gestures, reciprocity, play, language, repetitive behaviour and sensory responses.
4. Examine clinically: growth and head circumference where appropriate, dysmorphic features, neurological status, hearing/vision concerns, nutrition and signs of a medical or genetic syndrome.
5. Use screening tools appropriately. A positive screen indicates need for fuller assessment; it is not a diagnosis. A negative screen does not overrule strong clinical concern.
6. Arrange comprehensive developmental assessment involving relevant paediatric, psychological, speech-language, occupational, educational and other services according to local availability.
7. Investigate selectively based on history and examination. Consider hearing/vision assessment; genetic, metabolic, EEG or neuroimaging investigations only when clinically indicated (e.g. regression, seizures, focal neurological signs or suspected syndrome). Routine EEG or brain imaging is not required for every child with ASD.
8. Assess comorbidities and needs: language disorder, ID, ADHD, anxiety, sleep or feeding problems, epilepsy, hearing/vision impairment and family stress.

7. Management principles

There is no single intervention suitable for every child. Set goals with the child/family and tailor support to strengths, communication, function and context.

• Psychoeducation and family partnership: explain the profile without blame or stigma; agree on practical goals and review progress.
• Communication support: speech and language therapy; augmentative and alternative communication (AAC) when useful. AAC does not need to wait until spoken language fails.
• Developmental and behavioural support: structured, individualised interventions to build communication, play, daily living and learning skills; use positive, respectful approaches.
• Education: reasonable adjustments, predictable routines when helpful, individual learning plans and collaboration with teachers.
• Occupational therapy: support participation in daily activities and functional sensory needs.
• ID support: teach adaptive skills in small achievable steps, support decision-making and independence, and assess safeguarding and vulnerability.
• Treat coexisting conditions according to their own evidence-based guidance. Medication does not treat the core features of ASD or ID; it may be considered by an appropriate clinician for specific coexisting symptoms or disorders, with monitoring.
• Follow-up: review function, participation, family priorities, safety, school inclusion and whether supports are accessible.

In Kenya, link families with available county child-health/development services, paediatric services, school-based support and relevant therapy or disability services. Availability varies; document the referral plan and interim support.

8. Differentials and common exam traps

• Hearing impairment: may present with poor response to name or delayed speech; check hearing.
• Developmental language disorder: language difficulty without the full ASD pattern of social-communication differences plus restricted/repetitive behaviours.
• Global developmental delay/ID: broad delays across domains; assess social communication relative to developmental level.
• ADHD: inattention/hyperactivity/impulsivity are central; ASD and ADHD can coexist.
• Anxiety, trauma or psychosocial adversity: may affect interaction or behaviour; establish timeline and context.
• Neurological/genetic conditions: especially when there is regression, seizures, abnormal neurological findings or dysmorphism.

Do not miss: regression; seizures; self-injury or risk of harm; severe feeding/sleep problems; safeguarding concerns; and caregiver exhaustion requiring support.

9. Short clinical case

A 4-year-old is referred because he rarely points to share interest, often does not respond to his name, repeats phrases from cartoons, becomes very distressed when the route to school changes and spends long periods arranging toy cars in rows. His language is delayed. His caregiver reports no loss of previously acquired skills.

Reasoning: social-communication differences plus repetitive speech/play and insistence on sameness raise concern for ASD. Language delay alone would not be enough. Obtain developmental and collateral history, assess hearing, observe communication and play, review functioning, screen for coexisting conditions and refer for comprehensive developmental assessment. Do not diagnose from this vignette alone.

Now suppose the same child also has marked difficulty learning age-appropriate concepts and needs substantial help with dressing, safety and daily routines. Assess intellectual and adaptive functioning as well; ASD and ID may co-occur.

10. Must-know recap

• ASD = persistent social-communication/interaction differences plus restricted/repetitive behaviours; early developmental onset and functional impact.
• ID = deficits in intellectual functioning and adaptive functioning, with developmental-period onset.
• Ask about development, social communication, play, routines, sensory features, daily functioning and regression.
• Hearing/vision problems and other developmental conditions must be considered.
• Screening supports but does not replace comprehensive clinical assessment.
• Management is individualised, multidisciplinary and function-focused; include caregivers and school.
• ASD and ID can coexist; severity/support needs are not determined by one score alone.

Practice questions

Short-answer questions

1. State the two core diagnostic domains of ASD.
2. Define intellectual disability and name its two required domains.
3. Give four developmental red flags that warrant assessment.
4. Why should hearing be assessed in a child with delayed speech?
5. Name four disciplines or settings that may contribute to a child's support plan.
6. What is the clinical significance of developmental regression?

MCQs

1. Which combination best describes ASD?

A. Delayed speech alone
B. Social-communication differences plus restricted/repetitive behaviours
C. Low school performance alone
D. Hyperactivity in every setting

Answer: B. Both core domains are required, with developmental onset and clinically significant impact.

2. Which statement about intellectual disability is most accurate?

A. IQ alone determines diagnosis and support needs
B. Adaptive functioning is irrelevant
C. Intellectual and adaptive functioning must both be assessed
D. It always has a known genetic cause

Answer: C. Assessment includes intellectual functioning and everyday adaptive functioning; cause may remain unknown.

3. A child loses previously acquired words and social skills. What is the best next step?

A. Reassure without assessment
B. Assume this confirms ASD
C. Arrange prompt medical and developmental evaluation
D. Start medication immediately

Answer: C. Regression requires prompt evaluation for neurological, medical and developmental causes.

4. A positive ASD screening result means:

A. Diagnosis is confirmed
B. No further assessment is needed
C. Comprehensive assessment should be considered
D. Intellectual disability is also confirmed

Answer: C. Screening identifies risk; it does not establish a diagnosis.

5. ASD and intellectual disability:

A. Cannot occur together
B. Always have identical support needs
C. May co-occur and should be assessed separately
D. Are diagnosed from language delay alone

Answer: C. Each condition has distinct diagnostic requirements, and both can be present.

Use current DSM-5-TR/ICD-11 criteria and local clinical referral pathways when assessing real patients. These notes support learning and do not replace supervised clinical assessment.