Intellectual Disability Flashcards
ICD 11 INTELLECTUAL DISABILITY DEFFINITION
A group of etiologically diverse conditions
originating during the developmental period
significantly below average intellectual functioning and adaptive behaviour
[approximately two or more standard
deviations below the mean
Intellctual Disability Levels and freguency
Mild: IQ 50-69, adult mental age 9-12 y 85%
Moderate: IQ 35-49, adult mental age 6-9 y 10%
Severe: IQ 20-34, adult mental age 3-6 y 4%
Profound: IQ under 20, adult mental age under 3 y 1%
Differential Diagnosis of ID
Sensory and communication problems
Environmental neglect
ASD
Severe ADHD (especially inattentive type)
Schizophrenia
Other psychopathology
Predisposing factors ( definite etiological connection)
1) genetic differences (including inborn errors of metabolism
[IEM]), accounting for 30%–50% of cases;
2)environmental influences and
exposure to toxins during prenatal development (e.g., fetal alcohol
syndrome), which affect 10% of cases;
3) pregnancy and perinatal
complications (e.g., trauma, prematurity, hypoxia), affecting 10% of cases;
4) acquired medical conditions (e.g., lead poisoning), affecting 5% of cases
Risk factors ( probably related to unknown cause)
mothers older than 35 years, Black mothers,
lower level of maternal education,
three or more births,
maternal alcohol use,
maternal epilepsy,
preterm birth,
male sex
low birth weight.
Most influential risk factors of idiopathic ID
I. low birth weight
II .maternal epilepsy
III. preterm birth.
Other significant, but weaker: maternal tobacco use, diabetes,
hypertension, and asthma.
Study on antipsychotics for agressive behaviour in ID
Tyrer et al, 2008:
Compared flexible doses of haloperidol, risperidone
and placebo, in 86 non-psychotic patients . randomly assigned to haloperidol (n=28), risperidone
(n=29), or placebo (n=29). Placebo group showed the greatest change
Congenital Syndromes and Neurobehavioral
Phenotypes in ID
Deletion Syndromes
Uniparental Disomy
Aneuploiies
X- linked syndromes
Chemotaxis Syndromes
Fetal Alcohol spectrum disorders
Inborn errors of metabolism
What is the prevalence of 16p11.2 deletion syndrome?
1 per 3,000–5,000
It accounts for approximately 0.4% of ID cases.
What are common comorbidities associated with 16p11.2 deletion syndrome?
- Mild ID
- Psychiatric disorders
- Developmental disorders
- Expressive language deficits
- Speech apraxia
What percentage of children with 16p11.2 deletion syndrome are diagnosed with ASD?
20%
What is the most frequent chromosomal microdeletion syndrome in humans?
22q11.2 deletion syndrome
What is the estimated prevalence of 22q11.2 deletion syndrome?
1:2,000–4,000
Di Georgi Syndrome mnemonic
C: congenital heart disease (particularly conotruncal anomalies)
A: abnormal facies (hypertelorism, low set ears, short philtrum, among others)
T: thymic hypoplasia
C: cleft palate/cellular immune deficiency
H: hypoparathyroidism with hypocalcaemia
22: deletion located on chromosome 22
What cognitive impairments are associated with 22q11.2 deletion syndrome?
- Cognitive control difficulties
- Attention issues
- Social cognition deficits
What is the prevalence of Williams syndrome (WS)?
1 per 7,500
What are characteristic features of Williams syndrome?
- Elfin appearance
- Stellate iris
- Connective tissue abnormalities
- Cardiac abnormalities
- Growth deficiency
What cognitive profile is typical for individuals with Williams syndrome?
Mild to moderate ID and learning disorders
What is the prevalence of Angelman syndrome (AS)?
1 per 12,000–20,000
What genetic causes underlie Angelman syndrome?
- Deletion of maternally inherited chromosome 15q11.2–q13
- Uniparental disomy of paternal chromosome 15
What is a distinctive neurocognitive profile of Angelman syndrome?
- Severe speech impairment
- Inattention
- Gait ataxia
- Inappropriate laughter
What is the estimated prevalence of Prader-Willi syndrome (PWS)?
1 per 10,000–30,000 births
What are common features of Prader-Willi syndrome?
- Hypotonia
- Global developmental delay
- Hyperphagia
- Obesity
What is the most common genetic cause of intellectual disability?
Down syndrome (DS)
What is the prevalence of FMR1-related disorders in males?
14 per 100,000
What conditions are associated with mutations in the FMR1 gene?
- Fragile X syndrome (FXS)
- Fragile X-associated tremor/ataxia syndrome
- FMR1-related primary ovarian insufficiency
What is the prevalence of Rett syndrome (RS) in females?
1 per 10,000–23,000
What is a characteristic presentation of classic Rett syndrome?
- Normal development followed by loss of functions
- Stereotypic hand-wringing movements
- Seizures
What are common symptoms of fetal alcohol spectrum disorders (FASDs)?
- Distinct facial anomalies
- Growth retardation
- CNS abnormalities
What is the prevalence of inborn errors of metabolism (IEM)?
1%–1.5%
What are common features of inborn errors of metabolism?
- Disruptions to metabolic genes
- Toxic accumulation of substances
- Impaired synthesis of required products
What types of treatments are available for inborn errors of metabolism?
- Dietary restriction
- Supplementation with deficient enzymes
What percentage of all cases of intellectual disability (ID) may be due to inborn errors of metabolism (IEM)?
2%–14%.
What symptoms may exacerbate when considering IEM?
Physiological stress, illness, abdominal pain, vomiting, or functional regression.
Studies in favor of antipsychotics for aggressive behaviour in ID
Risperdone : A recent meta-analysis of 14 studies found shortterm beneficial effects
(McQuire et al. 2015).
In a 48-week open-label study Turgay et al. (2002) average
dosages of 1.38 mg/day maintenance of improvement.
In multiple studies, risperidone at a low dosage of 0.4–3.0 mg/day yielded
significant improvement and was better tolerated than higher dosages (Aman et al. 2002; Zarcone et al. 2001).
Aripiprazole at a mean dosage of
9.8 mg/day improved irritability in a 12-week prospective trial in patients with fragile X syndrome (Erickson et al. 2011).
What term has replaced the term mental retardation?
Intellectual disability (ID)
The change reflects a shift towards more respectful and accurate terminology.
What are the three diagnostic criteria for a diagnosis of ID?
- Deficits in intellectual function
- Deficits in adaptive function in one or more areas
- Onset during the developmental period
These criteria ensure a comprehensive assessment of the individual’s abilities.
What percentage of ID cases are of unknown etiology?
30%–50%
This percentage is decreasing with advancements in testing methods.
What are some current known causes of intellectual disability?
- Chromosomal changes
- Exposure to toxins during prenatal development
- Heredity (single-gene abnormalities, chromosomal defects, inborn errors of metabolism)
- Pregnancy and perinatal complications
- Acquired medical conditions
- Environmental influences
Understanding these causes is crucial for prevention and intervention.
How does development in children with ID compare to children with typical development?
It occurs in the same sequence but at a different rate
Development may be speeded or slowed at various ages and related to different developmental tasks.
What does a clinical evaluation for ID often include?
- Clinical history and physical exam
- Cytogenetic diagnostic testing
- Metabolic testing
- Neuroimaging
- Electroencephalography
This comprehensive evaluation helps in understanding the child’s condition.
What are common issues regarding mental health disorders in youth with ID?
- Often unrecognized
- Undiagnosed
- Untreated
These issues highlight the need for better mental health care access.
What should treatment for ID consider?
- Child’s developmental level
- Social and environmental factors
- Psychological factors (capacity to learn problem-solving skills)
- Biology
An integrative approach is essential for effective treatment.
