Educational resource only — this page helps students conceptualize diagnostic presentations and is not intended for clinical decision-making or self-diagnosis. Content may contain gaps or simplifications. Always verify against current clinical references and follow your institution’s protocols.
F70-F89

Neurodevelopmental Disorders (Expanded)

Intellectual Disability, Tourette's, Tic Disorders, Learning Disorders, Communication Disorders, Dyslexia, Dyscalculia
Diagnostic Category
Neurodevelopmental Disorders
Key Features
  • Intellectual Disability (Intellectual Developmental Disorder): Deficits in intellectual AND adaptive functioning with onset during the developmental period. Severity is classified by adaptive functioning, not IQ score. Affects approximately 1% of the population, with mild severity comprising 85% of cases.
  • Tourette's Disorder and Tic Disorders: Tourette's requires multiple motor tics AND at least one vocal tic, onset before age 18, duration >1 year. Tic disorders exist on a hierarchy - Tourette's > persistent motor or vocal tic disorder > provisional tic disorder. Prevalence of Tourette's is 0.3-0.8% in school-age children, with a male-to-female ratio of approximately 3:1.
  • Specific Learning Disorders: Persistent difficulties in reading (dyslexia), written expression (dysgraphia), or mathematics (dyscalculia) that are substantially below expected for age despite adequate instruction and intelligence. Prevalence is 5-15% of school-age children across languages and cultures.
  • Communication Disorders: Includes language disorder, speech sound disorder, childhood-onset fluency disorder (stuttering), and social (pragmatic) communication disorder. Social communication disorder involves persistent difficulties in social use of verbal and nonverbal communication and is a critical differential diagnosis for ASD.

Red Flags & Key Clinical Considerations

Classifying Intellectual Disability Severity by IQ Alone

DSM-5 bases ID severity on adaptive functioning, not IQ. A patient with IQ 55 who lives independently = mild. A patient with IQ 65 requiring 24-hour supervision = more severe. Using IQ cutoffs alone (mild 50-70, moderate 35-49) reflects outdated systems.

Diagnosing SCD When Restricted/Repetitive Behaviors Are Present

SCD cannot be diagnosed if any RRBs are present - even subtle ones like intense circumscribed interests or insistence on sameness. If social communication deficits + any RRBs = ASD, not SCD. Always screen the vignette for RRBs before selecting SCD.

Withholding Stimulants from All Patients with Tourette's and ADHD

Stimulants are not absolutely contraindicated in Tourette's - current evidence shows they do not reliably worsen tics. Options include alpha-2 agonists (treat both conditions) or careful stimulant use with monitoring. Untreated severe ADHD causes more harm than potential tic exacerbation.

Confusing Tic Hierarchy Diagnoses

Motor + vocal tics >1 year = Tourette's, not persistent motor tic disorder + persistent vocal tic disorder. Only the highest hierarchy diagnosis is given. Provisional tic disorder = tics

References & Further Reading

This educational summary synthesizes information from standard clinical references for learning purposes. It is not a substitute for primary sources. Always verify against current clinical guidelines before applying any content in practice.

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