Intellectual developmental disorder / Intellectual disability
IDD is characterised by global difficulties in information processing (may still see variation in profile though) Distinct from special learning disability and illness or injury (neurocognitive disorder)
IDD diagnostic criteria
Intellectual and adaptive functioning deficits in conceptual, social, and practical domains with the following 3 criteria being met:
- A. Deficits in intellectual functioning
- Reasoning
- Problem solving
- Planning
- Learning
- Judgement
- B. deficits in adaptive functioning that result in failure to meet developmental and social standards for personal independence and social responsibility
- communication
- social participation
- independant living
- across multiple environments (home, school, community)
- Onset of intellectual and adaptive deficits during the developmental period
What does this look like
May not be obvious: Early recognition more likely if
- severe impairment
- Impairment across multiple domains of function
- Delayed milestones
- presence of multiple risk factors
Risk factors
- Adverse postnatal development
- Deprivation of nurturance and other stimulation
- Pregnancy and perinatal problems
- fetal malnutrition, prematurity, hypoxia, viral and other infections. trauma
- general medical conditions
- seizure disorders, infections, etc
Prevalence and etiology
• Prevalence • Estimates range from 1 – 3% • Males > females • Etiology often undetermined • 30 – 40% • Strong genetic/heredity component • >500 genetic disorders associated with ID • Down Syndrome • Fragile-X syndrome • Tuberous sclerosis • Adverse prenatal environment • Fetal alcohol syndrome • Lead poisoning • Maternal infection • Pervasive Developmental Disorders
Comorbidity
• Very common (range 10 – 70%) • Type may vary according to severity of IQ impairment • Depression, anxiety, antisocial more common in those with higher levels • Psychotic, autism spectrum disorder more likely in lower levels • Challenging behaviour common • ?reflects emotional problems • Maltreatment common (cause or outcome?) • Beware diagnostic overshadowing
Respect dignity and equity
Treat person with respect 25 yr old with information processing facilities of a 15yr old should not be treated as a 15 yr old