PS10.1,PS11.1 | Developmental Psychiatry — Graded Quiz

Correct. DSM-5 specifies three presentations: predominantly inattentive (≥6 inattentive symptoms, <6 hyperactive-impulsive), predominantly hyperactive-impulsive (reverse), and combined (≥6 of both). This girl has only inattentive features with no hyperactivity.

DSM-5 ADHD presentations: predominantly inattentive, predominantly hyperactive-impulsive, combined. The inattentive type is more common in girls and often under-recognised because children are not disruptive.

This clinical picture — inattention, forgetfulness, easy distractibility, organisational problems — with no hyperactivity or impulsivity fits the predominantly inattentive presentation of DSM-5 ADHD. Girls are more often diagnosed with this subtype, which may explain later referral.

Correct. DSM-5 explicitly removed the exclusion that was present in DSM-IV. Concurrent ASD+ADHD diagnosis is now supported. Methylphenidate can be used for ADHD symptoms in children with ASD, though response rates and side effect profiles may differ.

DSM-5 paradigm shift: ASD+ADHD co-diagnosis is now standard practice when criteria for both are independently met. Up to 50% of children with ASD have clinically significant ADHD symptoms.

DSM-IV precluded ADHD diagnosis in ASD; DSM-5 permits it. Both diagnoses can coexist. ADHD comorbidity in ASD is common (30-50%). Methylphenidate is used (though with somewhat variable response in ASD).

Correct. This vignette illustrates deficits in pragmatic/social communication (inability to interpret non-literal language, jokes) and social interaction (lack of friends, failure to read social cues). High intelligence does not protect against social-communication deficits in ASD.

ASD social-communication deficits include: reduced eye contact, failure to read social cues, impaired pragmatics (literal interpretation, difficulty understanding humour/sarcasm), deficits in joint attention, and challenges with perspective-taking (Theory of Mind deficit).

The core DSM-5 ASD domain being tested here is social communication and social interaction deficits — specifically pragmatic language use, non-verbal communication, and social reciprocity. Academic ability is preserved in high-functioning ASD but social-communication deficits persist.

Correct. ADHD has high heritability (approximately 70-80% in twin studies). Neurobiological research implicates dysregulation of dopaminergic (and noradrenergic) pathways in the prefrontal cortex and striatum — consistent with the mechanism of action of methylphenidate (dopamine/norepinephrine reuptake inhibition).

ADHD aetiology: genetic (heritability ~70-80%, multiple gene variants — DRD4, DAT1), neurobiological (frontostriatal dopamine/noradrenaline dysregulation), neuroimaging (smaller prefrontal cortex, caudate). Environmental factors (prenatal smoking, lead exposure) contribute modestly.

ADHD is a neurodevelopmental disorder with strong genetic (heritability ~70-80%) and neurobiological (dopaminergic/noradrenergic) basis. Parenting style, diet, and screen time may influence symptom severity but do not cause ADHD.

Correct. DSM-5 requires BOTH intellectual deficits AND significant adaptive functioning deficits for IDD. This boy's IQ is 72 (borderline range, not below the ~70 threshold), and adaptive functioning is essentially preserved. He does not meet criteria for IDD. The correct approach is to grade IDD only when adaptive deficits co-occur with intellectual deficits.

Borderline Intellectual Functioning (IQ 71-84) is a DSM-5 V-code, not a disorder. Adaptive functioning assessment is mandatory — preserved adaptive functioning with a low-normal IQ does not qualify for IDD. Severity in IDD is graded by adaptive function, not IQ.

IDD requires concurrent intellectual deficits (IQ ~≤70) AND significant adaptive functioning deficits. This boy's IQ is 72 (borderline, above typical IDD threshold) and his adaptive functioning is preserved. Neither criterion is met. DSM-5 never bases severity on IQ alone.

Correct. In IDD, pharmacotherapy is targeted at specific comorbid psychiatric disorders or behaviours (e.g., risperidone or aripiprazole for severe aggression/self-injury; methylphenidate for comorbid ADHD; SSRIs for comorbid OCD or depression). No drug reverses the underlying intellectual disability.

IDD pharmacotherapy principles: (1) treat specific comorbidities (ADHD → stimulants; severe aggression/SIB → atypical antipsychotics; depression → SSRIs; epilepsy → anticonvulsants); (2) start low, go slow; (3) regularly review and attempt tapering; (4) never use polypharmacy as default.

Pharmacotherapy in IDD is symptom/comorbidity-targeted — not curative. Atypical antipsychotics (risperidone, aripiprazole) are used for severe aggression or self-injurious behaviour. Stimulants may help comorbid ADHD. No drug improves intellectual functioning.

Correct. Fragile X syndrome is the most common single-gene (monogenic) cause of intellectual disability in males. It is caused by a CGG trinucleotide repeat expansion in the FMR1 gene on the X chromosome (>200 repeats = full mutation, methylation of FMR1 → loss of FMRP). Down syndrome (Trisomy 21) is the most common chromosomal cause overall.

IDD aetiology hierarchy: (1) Most common chromosomal cause overall = Down syndrome (Trisomy 21); (2) Most common single-gene/inherited cause = Fragile X syndrome (FMR1 CGG repeat expansion, X-linked). Clinical features of Fragile X: macro-orchidism, large ears, long face, hyperactivity, autistic features, variable IDD (mild to severe).

Down syndrome (Trisomy 21) is the most common chromosomal cause of IDD overall. Fragile X syndrome is the most common SINGLE-GENE cause and the most common inherited cause of IDD, predominantly affecting males.

Correct. DSM-5 requires specifiers for ASD: presence or absence of intellectual impairment AND presence or absence of language impairment. This boy has IQ 35 (moderate to severe IDD) and no speech (language impairment). Both specifiers apply. DSM-5 also assigns severity levels (1-3) based on support needs in each domain.

DSM-5 ASD requires specifiers: (1) with/without intellectual impairment (IQ ≤70 = impaired), (2) with/without accompanying language impairment (no functional speech/phrase speech = impaired), (3) associated with a known medical/genetic condition or environmental factor, (4) associated with another neurodevelopmental/mental/behavioural disorder, (5) with catatonia.

DSM-5 ASD specifiers include: presence/absence of intellectual impairment (IQ ~≤70 = impairment present), presence/absence of language impairment (no functional speech = impairment present). Both apply in this case. ASD and IDD can be co-diagnosed.

Correct. Neonatal bloodspot screening (Guthrie test) identifies PKU — an autosomal recessive disorder of phenylalanine hydroxylase (PAH). Elevated phenylalanine accumulates and is toxic to the developing brain. Early diagnosis and phenylalanine-restricted diet prevents IDD. This is the model example of preventable IDD through newborn screening.

Prevention of IDD — postnatal: (1) neonatal metabolic screening (PKU, hypothyroidism, galactosaemia); (2) newborn hearing screening; (3) immunisation (measles, Hib, rubella). Antenatal: folic acid (neural tube defects), antenatal screening for Down syndrome, avoidance of teratogens. Primary prevention is the most cost-effective IDD intervention.

The Guthrie neonatal screen detects elevated phenylalanine, indicating PKU (phenylalanine hydroxylase deficiency). Early dietary intervention prevents phenylalanine toxicity to the developing brain and IDD. Down syndrome cannot be prevented by neonatal screening; Fragile X has separate genetic testing; congenital rubella is prevented by maternal immunisation.

Correct. Evidence-based ADHD management is multimodal: stimulant medication (methylphenidate first-line), combined with behaviour therapy, psychoeducation for family and school, academic accommodations, and social skills training. The MTA study (NIMH Multimodal Treatment Study) showed combined treatment was superior to either medication or behavioural intervention alone for most outcomes.

ADHD multimodal management: (1) Pharmacotherapy — methylphenidate first-line (stimulant); atomoxetine (non-stimulant) second-line; (2) Behaviour therapy — parent training, classroom behavioural strategies; (3) Psychoeducation — family, teachers, child (age-appropriate); (4) Academic accommodations — extended time, preferential seating; (5) Social skills training.

ADHD management is multimodal — medication is effective but insufficient alone. The combination of pharmacotherapy, behavioural strategies, psychoeducation, and school accommodations produces the best outcomes (MTA study evidence). Dietary changes have limited evidence and are not first-line.