Intellectual disability

Question 1

What is the definition of intellectual disability?

Answer 1

Significantly low intellectual functioning - IQ<70

• Impairments in adaptive behaviour when taking into account age
• Onset of intellectual impairment before 18

Question 2

What is mild intellectual disability?

Answer 2

IQ: 50-69
1.5-3% prevalence 
85% of all IDs
Learning disability 
Need help if problems arise
Can sustain relationships and hold a routine job

Question 3

What is moderate intellectual disability?

Answer 3

IQ: 35-49
0.5% prevalence
Capable os substantial autonomy in daily living with some supervision
Can communicate adequately and do simple household tasks
May need a supervised environment and work in sheltered workshop

Question 4

What is severe intellectual disability?

Answer 4

IQ: 20-24
0.5% prevalence 
Need help with daily living 
Can wash and usually continent 
Often physically disabled 
Only limited communication, often not by speech 
Need continuous care

Question 5

What is profound intellectual disability?

Answer 5

IQ: <20
0.05% prevalence 
Need extensive or total help with daily living 
Minimal communication 
Need continuous care

Question 6

What is the aetiology of intellectual disability?

Answer 6

More common in males and higher prevalence in lower social classes
Associated with - overcrowding, poverty, irregular unskilled employment
30% have NO identifiable cause
Can be a POLYGENETIC inheritance of low intelligence Environmental - social and educational deprivation Genetic/chromosomal factors
Pre-natal, perinatal and post-natal factors

Question 7

What is down’s syndrome?

Answer 7

Trisomy 21
Most common cause
Characteristic physical abnormalities
Increased risk of deafness, cataracts, hypothyroidism and early onset AD

Question 8

What is fragile X syndrome?

Answer 8

abnormality on long arm of chromosome X
2​nd most common cause
More common in males
Physical abnormalities - elongated face, protruding ears

Question 9

What causes Cri du chat syndrome?

Answer 9

Deletion of short arm of chromosome 5

Question 10

What is tuberous sclerosis?

Answer 10

Mutation in tumour-suppressor gene on chromosome 9 or 16
Results in autism or epilepsy with ID
Skin changes and tumours of the brain/other organs

Question 11

What is neurofibromatosis?

Answer 11

mutation of gene on chromosome 17
Usually with mild ID
Abnormalities of skin, soft tissues, nervous system and bone

Question 12

What is phenylketonuria?

Answer 12

1/10,000
Autosomal recessive
High serum phenylalanine
ID with short stature, hyperactivity, irritability, epilepsy, lack of pigment and
eczema

Question 13

What are prenatal causes of intellectual disability?

Answer 13

Congenital infection- rubella, toxoplasmosis, CMV, syphilis 
Foetal alcohol syndrome 
Drugs- illicit or teratogenic 
Placental insufficiency 
Congenital hypothyroidism 
Pre-eclampsia

Question 14

What are perinatal causes of intellectual disability?

Answer 14

Hyperbilirubinaemia
Intraventricular haemorrhage
Birth trauma and hypoxia

Question 15

What are postnatal causes of intellectual disabilities?

Answer 15

Childhood brain tumour 
Malnutrition 
Brain infection- meningitis, encephalitis 
Head injury 
Chronic lead poisoning

Question 16

What are the environmental causes of intellectual disability?

Answer 16

Poor, socioeconomically deprived
Neglect
Poor linguistic and social stimulation
Abuse

Question 17

What are possible presenting features in autism and ID?

Answer 17

Repetitive movements
Little interaction with mother
Do not run to greet parents
Little eye contact
Speech - no speech, repetition, pronoun reversal
Poor non-verbal communication
No imaginative play
Carry the same object around
Can be clumsy at copying movements
Temper tantrums

Question 18

What are the classical features of Asperger’s syndrome?

Answer 18

Good speech but literal and long winded
Long monologues regardless of response
Monotonous
Good memories but not interested in wider applications
Lack of common sense
Physically clumsy

Question 19

What is the behavioural approach for the management of autistic spectrum disorder?

Answer 19

Graded changes:
Deal with obsessions 
Aim to reduce frequency gradually
Positive reinforcement and reward
Setting limits:
Tackle challenging behaviour
Interrupt destructive behaviour but avoid the word no
Use short and concrete explanation
Allow tantrum to run itself out
Education:
Provide framework for order, routine and structure Physical prompting and visual demonstration to help understanding
Teaching material is precise and specific
Help develop any skills
Others:
Counsel the parents 
Medication is not very useful
Aggressive outbursts can usually be understood by environmental factors

Question 20

How can schizophrenia present in those with ID?

Answer 20

Hard to diagnose with IQ <45
More common with more severe ID
Poverty of thought
Distinguish negative symptoms from deterioration in previous level of functioning
Can present with fear, withdrawal, challenging behaviour and sleep disturbance
Delusions are less elaborate
Hallucinations are SIMPLER and REPETITIVE
Persecutory delusions and thought disorder are LESS common Earlier age of onset

Question 21

How does ID effect epilepsy?

Answer 21

More common in severe ID
44% of patients with at least moderate ID have epilepsy by the age of 22
4 times more common in males
Need to have caution with psychiatric medications- may lower seizure threshold
Compliance to drugs may be an issue
Inadequate control of fits can lead to poly pharmacy
Recording of fits may be difficult
Need to assess for side effects of anticonvulsant medication
Need to recognise non-epileptic attacks
Frequent attacks may lead to overprotection by carers/parents
Need to educate parents/carers about emergency treatment of prolonged fits
Social implications of epilepsy need to be considered

Question 22

How can adaptive functioning in ID be achieved?

Answer 22

Educational and vocational programmes
Family education and support
Behaviour therapy for behavioural difficulties
Medication may be needed for aggressive/destructive behaviour- antipsychotics, benzodiazepines, lithium, carbamazepine
Appropriate residential placement
Treatment of co-morbid psychiatric and medical conditions