Intelligence and Intellectual Disability Flashcards
Acquire basic understanding of the concepts of intelligence and intellectual disability Be familial with measures for and testing of intelligence and how to recognise this clinically Know the main reasons for variation in intelligence Know the common associations between intellectual disability and psychiatric disorder, and mechanisms for those associations
Define intelligence
The ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly, and learn from experience - the mental abilities necessary for adaptation to, as well as selection and shaping of, any environmental context
What is the intelligence quotient (IQ)?
Mean age divided by chronological age, multiplied by 100
State the domains of IQ on the Wechsler adult intelligence scale (WAIS)
Verbal comprehension index and working memory index (verbal IQ) plus perceptual organisation index and processing speed index (performance IQ)
State some environmental factors influencing intelligence
Foetal growth, intrauterine infections, birth complications, quality of childhood care, quality of school. peer group, socioeconomic deprivation
Describe the evidence for environmental factors from adoption studies
A child reared in a socially advantaged adoptive family will have a higher IQ than a comparable child reared in a socially disadvantaged family
State the monozygotic twin concordance for intelligence when reared together and apart
Together: 86%
Apart: 76%
State the sibling concordance for intelligence when reared together and apart
Together: 47%
Apart: 24%
State the IQ range of an individual with mild intellectual disability
50-69
State the IQ range of an individual with moderate intellectual disability
35-49
State the IQ range of an individual with severe intellectual disability
20-34
State the IQ range of an individual with profound intellectual disability
<20
What might an individual with mild intellectual disability be able to attain by adulthood?
Self-help skills and good speech are definitely attainable. Literacy and semi-skilled work should also be attainable.
What might an individual with moderate intellectual disability be able to attain by adulthood?
Self-help skills, domestic speech, and unskilled work - possibly with supervision - should be attainable. Literacy is sometimes attainable.
What might an individual with severe intellectual disability be able to attain by adulthood?
Assisted self-help skills, minimum speech, and assisted ability to do household chores
What might an individual with profound intellectual disability be able to attain by adulthood?
Some individuals will obtain speech and self-help skills
Below what IQ does intellectual disability definitely have a pathological cause?
50
What percentage of individuals with mild and severe learning disabilities respectively are male?
Mild: 46%
Severe: 63%
What percentage of individuals with mild and severe learning disabilities respectively have a concurrent major CNS disorder?
Mild: 14%
Severe: 72%
Name at least 5 prenatal conditions associated with intellectual disability
Down’s syndrome, fragile X, tuberous sclerosis, William’s syndrome, neurofibromatosis, inborn errors of metabolism (phenylketonuria, galactosaemia), cereberal palsy, IU infections, IU toxins
Name 2 perinatal conditions associated with intellectual disability
Neonatal jaundice, obstetric complications
Name 2 post-natal conditions associated with intellectual disability
Meningitis, trauma
What is involved in managing intellectual disability?
Early detection, parental genetic counselling and support, early treatment if applicable (e.g. for IEOM), management of comorbid physical disorders (e.g. epilepsy), helping parents manage challenging behaviours, treating comorbid psychiatric disorders, education (special schools or mainstream with support)
State at least 5 physical features of Down syndrome
Small head, round face, epicanthic folds, large fissured tongue, low-set ears, short stature, cardiac malformations, GI malformations, single palmar crease, incurved little finger, inc. risk deafness, inc. risk visual problems, inc. risk AD
State the incidence of Down syndrome
1 in 600 births
What is the biggest risk factor for Down syndrome?
An older mother
What percentage of intellectual disability cases are due to Down syndrome?
33%
What is the typical IQ of an individual with Down syndrome?
30-70
Name the 3 genetic causes of Down syndrome
Extra copy of chromosome 21 (95% of cases), translocations (4%), mosaics (1%)
Name a mental health disorder which individuals with Down syndrome are at risk of in adolescence
Depression
State at least 3 physical features of fragile X
Large head with high forehead, prominent ears, mild facial hypoplasia & prognathism, connective tissue problems (joint laxity, flat feet), occasionally mitral valve prolapse, occasionally childhood epilepsy
Describe the prevalence of fragile X
1 in 4,000 males; partial phenotype in 1 in 8,000 females
What causes fragile X?
Deficiency in or absence of fragile X mental retardation protein 1 (FMR1) due to an expansion of CGG trinucleotide repeats on the FMR1 gene on chromosome Xq27.3
Above how many trinucleotide repeats is the FMR1 protein no longer made?
200
What is the normal number of trinucleotide repeats on the FMR1 gene?
5-20
State some cognitive features of fragile X
Cognitive impairment (male IQ <50; female IQ 60-80), impaired short-term visuospatial memory, impaired motor planning, repetitive and impulsive interactional style, speech deficits (immature expressive syntax)
State some behavioural features of fragile X
Social anxiety, gaze avoidance, mood disturbance, inattentiveness, fidgety and restless behaviour
State the 2 main features of tuberous sclerosis
Skin lesions and infantile spasms (epilepsy)
Describe the skin lesions of tuberous sclerosis
Areas of hypopigmentation, adenoma sebeceum (facial adenofibromas), shagreen patch (orange-peel like patch in lumbosacral region)
Describe the CT features of tuberous sclerosis
Cortical hamartomas, white matter abnormalities, subependymal nodules (hamartomas)
State the prevalence of tuberous sclerosis
1 in 6,000
Name the 2 genes which can cause tuberous sclerosis, their location, and the protein they code for
TSC1, chromosome 9q34, codes hamartin
TSC2, chromosome 16p13, codes tuberin
Describe the relationship between seizures and intellectual disability in tuberous sclerosis
Severity of intellectual disability is linked to severity of seizures; below 50% of patients have intellectual disability
What percentage of tuberous sclerosis patients meet the diagnostic criteria for ADHD?
50%
State some cognitive deficits in tuberous sclerosis
Dyspraxia, speech delay, dyscalculia, childhood inattention, autistic features, poor peer-peer relationships
Describe the facial features of William’s syndrome
‘Elf-like’ features - wide mouth, large flattened bridge of nose, slightly bulgy cheeks, irregular widely-spaced teeth, squint
Describe the early problems associated with William’s syndrome
Low birth weight, delay in meeting physical milestones, slow weight gain (sometimes weight loss), below average growth, slow feeding, restless sleeping, irritability
State the incidence of William’s syndrome
1 in 7,500
What is the most common cause of William’s syndrome?
Micro-deletion of part of chromosome 7 at 7q11.1 - the region containing the genes for elastic, lim kinase 1, and general transcription factor II (GTF21)
State some behavioural features of William’s syndrome
Low intellectual ability (language delay, weak pragmatics of speech, reduced visuospatial skills), difficulty in social interactions 9good empathy but lack of reciprocity), early hyperactivity, hypersensitivity to noise, obsessional interests, emotional immaturity
Is William’s syndrome inherited or sporadic?
Sporadic
