Cognitive · Lifelong
Intellectual Disability (ID)
Significant limitations in intellectual functioning AND adaptive behavior — both domains matter equally.
🎨 Analogy
Intellectual disability is like a city where both the roads and the buildings need rebuilding — it's not just about raw cognitive processing speed (IQ), but about how well a person can navigate daily life (adaptive functioning). A child might score low on an IQ test but be remarkably independent and functional — and vice versa. The diagnosis requires both domains to be significantly limited, because the goal isn't a number — it's understanding how the child moves through the world.
DSM-5 Diagnostic Criteria
- Deficits in intellectual functioning (reasoning, problem solving, planning, abstract thinking, learning) — confirmed by clinical assessment + standardized IQ testing
- Deficits in adaptive functioning — conceptual, social, and practical domains — that fail to meet developmental/sociocultural standards
- Onset during the developmental period (before age 18)
- IQ ≤70 (approximately –2 SD below mean) — but IQ alone does NOT define the diagnosis
- Severity classified by adaptive functioning, not IQ score alone
Severity Levels
| Level | IQ (approx) | Adaptive Function |
|---|---|---|
| Mild | 50–70 | Academic difficulties; may live independently with support |
| Moderate | 35–50 | Can learn basic skills; needs supervision |
| Severe | 20–35 | Limited communication; needs significant support |
| Profound | <20 | Minimal self-care; continuous supervision |
Common Etiologies
- Genetic: Down syndrome (Trisomy 21), Fragile X, Prader-Willi, Angelman, PKU (untreated)
- Prenatal: TORCH infections, alcohol (FASD most common preventable cause), teratogens, iodine deficiency
- Perinatal: HIE, prematurity, kernicterus
- Postnatal: meningitis/encephalitis, TBI, lead poisoning, severe neglect
- Idiopathic — no identifiable cause found in many cases
- FASD (Fetal Alcohol Spectrum Disorder) — most common preventable cause of ID ⭐
Evaluation & Management
- Developmental surveillance at every well-child visit
- Formal developmental testing when concerns arise
- Workup: chromosomal microarray (first-line genetic test), Fragile X DNA, metabolic screen, MRI brain, hearing/vision screen
- Chromosomal microarray — highest yield single genetic test for unexplained ID
- Early intervention (EI) — birth to age 3: PT, OT, speech
- IEP (Individualized Education Plan) — school-based services
- Transition planning — adult services, vocational training
- Treat comorbidities: epilepsy, ADHD, anxiety, behavioral issues
💡 Board Pearl
First-line genetic test for unexplained intellectual disability = chromosomal microarray (detects copy number variants missed by standard karyotype). If negative and male → Fragile X DNA testing. If both negative → whole exome sequencing becoming more common.
Academic · School-Age
Learning Disabilities (SLD)
Average or above intelligence — but a specific brain-based difficulty in reading, writing, or math.
Defining Characteristics
- Specific Learning Disorder (DSM-5) — average or above intelligence with specific academic deficits
- NOT due to: intellectual disability, sensory impairment, inadequate instruction, or psychosocial adversity
- Persistent difficulties despite adequate instruction
- Three domains:
- Reading (dyslexia) — most common; phonological processing deficit
- Written expression (dysgraphia) — spelling, grammar, handwriting
- Mathematics (dyscalculia) — number sense, calculation, math reasoning
Dyslexia — Most High-Yield
- Most common learning disability — ~5–15% of school-age children
- Core deficit: phonological processing — difficulty matching letters to sounds
- Signs: difficulty learning letter sounds, slow/inaccurate reading, poor spelling despite normal intelligence
- Neurobiological origin — runs in families (50–60% heritability)
- NOT caused by vision problems or "seeing letters backwards"
- Strong association with ADHD (~40% comorbidity)
- Diagnosis: psychoeducational testing — discrepancy between IQ and reading achievement
Evaluation & Management
- Hearing and vision screen first — rule out sensory causes
- Psychoeducational evaluation — standardized academic and cognitive testing
- School-based: IEP or 504 Plan
- Structured literacy instruction (Orton-Gillingham method) — most evidence-based for dyslexia
- Accommodations: extended time, audiobooks, text-to-speech, reduced reading load
- Screen for and treat comorbid ADHD, anxiety, depression
- Early identification and intervention = best outcomes
504 Plan vs. IEP
- 504 Plan (Section 504, Rehab Act):
- Accommodations only (extended time, preferential seating, assistive tech)
- For students who need accommodations but not specialized instruction
- Less intensive, easier to establish
- IEP (Individuals with Disabilities Education Act):
- Specialized instruction + services + accommodations
- For students who need modified curriculum or direct special ed services
- More comprehensive; annual review required
Neurodevelopmental · Most Common
ADHD
The most commonly diagnosed neurodevelopmental disorder — and the one with the most board-testable medication details.
🎨 Analogy
Think of executive function as a conductor leading an orchestra. The conductor's job is to cue the right instruments at the right time, keep the tempo, and suppress instruments that are playing out of turn. In ADHD, the conductor is understaffed and undertrained — not because the musicians are bad, but because the prefrontal cortex (where the conductor lives) has lower dopamine and norepinephrine signaling. Stimulant medications essentially give the conductor a megaphone and a clear score — the orchestra can finally play together.
DSM-5 Diagnostic Criteria
- ≥6 symptoms of inattention AND/OR ≥6 symptoms of hyperactivity-impulsivity (≥5 if age ≥17)
- Symptoms present for ≥6 months
- Onset before age 12 years
- Symptoms present in ≥2 settings (home + school) ⭐
- Symptoms interfere with functioning
- Not better explained by another condition
- Presentations: Predominantly Inattentive, Predominantly Hyperactive-Impulsive, Combined (most common)
Inattention Symptoms
- Fails to pay close attention / makes careless mistakes
- Difficulty sustaining attention in tasks
- Does not seem to listen when spoken to directly
- Does not follow through on instructions / fails to finish tasks
- Difficulty organizing tasks
- Avoids tasks requiring sustained mental effort
- Loses things necessary for tasks
- Easily distracted by extraneous stimuli
- Forgetful in daily activities
Hyperactivity-Impulsivity Symptoms
- Fidgets/taps hands or feet, squirms in seat
- Leaves seat when expected to remain seated
- Runs/climbs when inappropriate (or feels restless in teens/adults)
- Unable to play quietly
- "On the go" / acts as if "driven by a motor"
- Talks excessively
- Blurts out answers before question completed
- Difficulty waiting turn
- Interrupts or intrudes on others
Evaluation
- Clinical diagnosis — no blood test or imaging required
- Information from multiple settings ⭐ — parent AND teacher report
- Standardized rating scales: Vanderbilt (most used in primary care), Conners
- Rule out: vision/hearing problems, learning disabilities, anxiety, depression, thyroid disorders, sleep disorders, lead poisoning
- Developmental and school history
- No routine neuroimaging or EEG needed for diagnosis
- Comorbidities: learning disabilities (40%), anxiety (50%), depression, ODD, conduct disorder, tic disorders, ASD
ADHD Medications — Board Gold
| Medication | Class | Age | Mechanism | Key Side Effects | Board Pearl |
|---|---|---|---|---|---|
| Methylphenidate (Ritalin, Concerta) | Stimulant — Schedule II | ≥6 years | Blocks dopamine + NE reuptake | ↓ appetite, insomnia, headache, ↑ HR/BP, growth suppression (monitor height) | Most studied ADHD medication; short-acting vs long-acting options |
| Amphetamine salts (Adderall, Vyvanse) | Stimulant — Schedule II | ≥6 years (Adderall); ≥6 (Vyvanse) | ↑ release + blocks reuptake of dopamine + NE | Same as methylphenidate; higher abuse potential | Vyvanse = prodrug (lisdexamfetamine) — lower abuse potential than Adderall |
| Atomoxetine (Strattera) | Non-stimulant — SNRI | ≥6 years | Selective NE reuptake inhibitor | GI upset, ↓ appetite, suicidal ideation (black box warning ⭐), hepatotoxicity | Good choice if: substance abuse concern, tics, stimulant intolerance. Takes 4–6 weeks to work. |
| Guanfacine (Intuniv) | Non-stimulant — alpha-2 agonist | ≥6 years | Alpha-2A agonist → ↑ prefrontal NE signaling | Sedation, hypotension, bradycardia, rebound HTN if stopped abruptly | Good for: tics, aggression, sleep, ADHD + ASD. Also used for Tourette's. |
| Clonidine (Kapvay) | Non-stimulant — alpha-2 agonist | ≥6 years | Alpha-2 agonist (less selective than guanfacine) | Sedation (more than guanfacine), hypotension, rebound HTN | Preferred for: bedtime use (sedating), tics, ADHD + Tourette's |
Age-Based Treatment Guidelines
- Ages 4–5: behavioral therapy FIRST — medication only if severe or inadequate response
- Ages 6–11: FDA-approved stimulant medication + behavioral therapy (combined best)
- Ages 12+: medication + behavioral therapy + academic support
- Behavioral therapy alone: age-appropriate for preschool; adjunct for all ages
- Parent training in behavior management — essential component at all ages
Stimulant Contraindications & Cautions
- Structural heart disease or arrhythmia — cardiac screening before starting
- Uncontrolled HTN
- History of psychosis or bipolar disorder
- Active substance use disorder (consider non-stimulant)
- Tic disorder — stimulants may worsen tics (consider guanfacine or clonidine)
- Growth monitoring: measure height/weight every 6 months
- Cardiac history: ECG before starting if family history of sudden death
Board Pearls — ADHD
- Symptoms must be in ≥2 settings — boards love this criterion
- Vanderbilt scale = primary care screening tool of choice
- Atomoxetine black box: suicidal ideation risk — monitor closely
- Stimulants → Schedule II controlled substances → cannot call in refills
- Inattentive ADHD more common in girls — often missed until later
- Preschool ADHD: behavior therapy FIRST, medication second
- Guanfacine = also used for tics and Tourette's syndrome
Social Communication · Neurodevelopmental
Autism Spectrum Disorder (ASD)
Deficits in social communication + restricted/repetitive patterns of behavior — a spectrum, not a single presentation.
🎨 Analogy
Imagine the social world as a complex unwritten rulebook that most people absorb unconsciously through observation and imitation. Children with ASD have a brain wired differently — they may not automatically pick up on the implicit rules: read the room, mirror facial expressions, understand unspoken subtext, or find comfort in eye contact. It's not a lack of intelligence or desire to connect — it's that the software for reading social context runs on a different operating system. The goal isn't to reprogram them into neurotypical children, but to give them tools to navigate a world designed for a different OS — and to help that world become more accommodating.
DSM-5 Diagnostic Criteria
- Domain A: Persistent deficits in social communication and interaction across multiple contexts:
- Deficits in social-emotional reciprocity
- Deficits in nonverbal communication (eye contact, gestures, facial expression)
- Deficits in developing/maintaining/understanding relationships
- Domain B: Restricted, repetitive patterns of behavior, interests, or activities (≥2 of 4):
- Stereotyped/repetitive motor movements or speech (echolalia, lining up toys)
- Insistence on sameness, inflexible routines
- Highly restricted, fixated interests
- Hyper- or hyporeactivity to sensory input
- Symptoms present in early developmental period (may not fully manifest until demands exceed capacity)
- Symptoms cause clinically significant impairment
Early Red Flags — When to Screen
- No babbling by 12 months
- No pointing or waving by 12 months
- No single words by 16 months
- No 2-word phrases by 24 months
- ANY loss of language or social skills at any age ⭐
- Poor eye contact
- Not responding to name by 12 months
- No social smile by 6 months
- Unusual sensory behaviors
Screening & Diagnosis
- M-CHAT-R/F (Modified Checklist for Autism in Toddlers) — screen at 18 and 24 months ⭐ (AAP recommendation)
- Developmental surveillance at every well-child visit
- Comprehensive evaluation: developmental pediatrician, psychology, speech-language pathologist
- Gold standard diagnostic tools: ADOS-2 (Autism Diagnostic Observation Schedule) + ADI-R
- Hearing test — always rule out first
- Chromosomal microarray + Fragile X — order at diagnosis
- EEG if seizures suspected
- MRI — not routine unless neurologic signs
Associated Conditions
- Intellectual disability (~30–40%)
- Epilepsy (~30%) — especially with ID
- ADHD (~50–70%) — most common comorbid neurodevelopmental
- Anxiety disorders (~40%)
- GI issues: constipation, food selectivity
- Sleep disorders (~80%) — insomnia, dysregulated sleep-wake
- Sensory processing differences
- Genetic: Fragile X, Tuberous sclerosis, Angelman, Rett syndrome, 22q11 deletion, PTEN mutations
- Increased risk of depression in adolescence
ASD Management — Evidence-Based
Core Interventions
1
ABA (Applied Behavior Analysis) ⭐
Most evidence-based behavioral therapy. Teaches communication, social skills, adaptive behavior through positive reinforcement. Intensive (20–40 hrs/week for young children).
2
Speech-Language Therapy
Core for communication deficits. AAC (augmentative/alternative communication) for nonverbal children.
3
Occupational Therapy
Sensory integration, fine motor skills, ADLs, feeding therapy.
4
Social Skills Training
PEERS program and similar group-based social skills instruction for school-age children/teens.
5
Educational placement
IEP with appropriate placement — inclusion with support or specialized classroom based on needs.
Pharmacotherapy — Targets Comorbidities
- No medication treats core ASD features (social communication, restricted behaviors)
- Risperidone (FDA approved ≥5 years) and Aripiprazole (FDA approved ≥6 years) — for irritability, aggression, self-injurious behavior ⭐
- Stimulants or guanfacine — for comorbid ADHD
- SSRIs — for anxiety, repetitive behaviors (mixed evidence in ASD)
- Melatonin — for sleep disorders (good evidence)
- Antiepileptics — if seizure disorder present
Board Pearls — ASD
- M-CHAT-R/F at 18 and 24 months — AAP universal screening
- ANY regression of language or social skills = immediate evaluation
- Hearing test FIRST before ASD evaluation — always rule out
- ABA = most evidence-based behavioral intervention
- Risperidone + aripiprazole = only FDA-approved meds for ASD (for irritability/aggression)
- Vaccines do NOT cause autism — this is settled science with overwhelming evidence
- Fragile X = most common known single-gene cause of ASD
- Melatonin: safe, effective for sleep in ASD
- Early intensive intervention = significantly better long-term outcomes
Neurodevelopmental Disorders — Rapid Comparison
| Disorder | Core Deficit | Intelligence | Key Diagnostic Tool | First-Line Treatment |
|---|---|---|---|---|
| Intellectual Disability | Intellectual functioning + adaptive behavior | ↓↓ (IQ ≤70) | IQ testing + adaptive scales; chromosomal microarray | Early intervention, IEP, treat comorbidities |
| Learning Disability | Specific academic domain (reading, writing, math) | Average or above | Psychoeducational testing (IQ vs. achievement discrepancy) | Structured literacy instruction, IEP/504 accommodations |
| ADHD | Attention, executive function, impulse control | Variable (often average) | Clinical + Vanderbilt rating scales (parent + teacher) | Stimulants (age ≥6); behavioral therapy (all ages; first-line age 4–5) |
| ASD | Social communication + restricted/repetitive behavior | Variable (30–40% have ID) | M-CHAT-R/F (screening); ADOS-2 (diagnostic) | ABA + speech + OT; risperidone/aripiprazole for irritability |
Board Quick Quiz · Flip to Reveal
Neurodevelopmental Flash Cards
tap any card to flip ↓
What is the most common preventable cause of intellectual disability?
Fetal Alcohol Spectrum Disorder (FASD) — prenatal alcohol exposure. Most common preventable cause of ID in the US. No safe amount of alcohol in pregnancy.
First-line genetic test for unexplained intellectual disability?
Chromosomal microarray — highest yield single genetic test. Detects copy number variants missed by standard karyotype. If negative + male → Fragile X DNA testing.
What are the DSM-5 ADHD criteria for number of symptoms, duration, and age of onset?
≥6 symptoms (≥5 if age ≥17) · Duration ≥6 months · Onset before age 12 · Present in ≥2 settings · Cause functional impairment.
4-year-old with ADHD symptoms. What is the first-line treatment?
Behavioral therapy FIRST for ages 4–5 — specifically parent training in behavior management. Medication is second-line in preschoolers. Stimulants first-line starting age 6.
Which ADHD medication carries a black box warning for suicidal ideation?
Atomoxetine (Strattera) — non-stimulant SNRI. Black box for suicidal ideation. Monitor closely especially in first months. Takes 4–6 weeks for full effect.
Child with ADHD also has Tourette's syndrome. Which ADHD medication is preferred?
Guanfacine (Intuniv) or clonidine (Kapvay) — alpha-2 agonists treat both ADHD and tics. Stimulants may worsen tics. Atomoxetine is another option.
When does AAP recommend universal ASD screening and with what tool?
M-CHAT-R/F at 18 months AND 24 months — AAP universal screening recommendation. Any developmental regression at any age → immediate evaluation regardless of prior screens.
What are the two FDA-approved medications for ASD — what do they treat?
Risperidone (age ≥5) and Aripiprazole (age ≥6) — both approved for irritability and aggression associated with ASD. No medication treats core ASD social/communication features.
What are ASD early red flags at 12 months?
No babbling · No pointing or waving · Not responding to name · No social smile (6 months). ANY loss of language or social skills at any age = immediate referral.
Do vaccines cause autism?
No — vaccines do NOT cause autism. This is settled science with overwhelming evidence from multiple large-scale studies worldwide. The original 1998 Wakefield study was fraudulent and retracted.
IEP vs. 504 Plan — what's the key difference?
IEP = specialized instruction + services + accommodations (IDEA). 504 = accommodations only, no specialized instruction (Rehab Act). IEP is more comprehensive; 504 is easier to establish.
Most evidence-based behavioral intervention for ASD?
ABA (Applied Behavior Analysis) — most evidence-based. Intensive (20–40 hrs/week). Teaches communication, social skills, adaptive behavior through positive reinforcement. Best outcomes when started early.