Psychiatry - Psychiatry of learning disability

Question 1

What is the definition of a learning disability?

Answer 1

LD is impairment of the CNS originating during the developmental period, which usually presents during early childhood with a below average intellectual performance and reduced ability to acquire life/adaptive skills resulting in social handicap.

Divided into mild, moderate, severe and profound

Question 2

Features of mild learning disability

Answer 2

IQ 50-69
Presents at school age
Limited in school work, but able to live alone and maintain some form of paid employment later on in life

Question 3

Moderate learning disability

Answer 3

IQ 35-49
Presents 3-5 years of age
Able to do simple work with support, needs guidance or support in daily living

Question 4

Severe learning disability

Answer 4

IQ 20-34
Presents before 2 years of age
Requires help with daily tasks and capable of only simple speech

Question 5

What is profound learning disability?

Answer 5

IQ <20
Presents before 2 years of age
Very disabled in all aspects

Question 6

Aetiology of learning disability

Answer 6

The cause of many cases of learning disability, especially mild forms is unknown, but they may be associated with the following:

1) Genetic
- chromosomal (Down’s syndrome)
- autosomal dominant (neurofibormatosis, tuberous sclerosis)
- autosomal recessive (phenylketonuria)
- sex linked (fragile X)

2) Structural developmental abnormalities: hydrocephalus
3) Secondary to brain damage
- antenatal (infection, toxin, hypoxic, maternal disease)
- perinatal (birth, asphyxia, intracranial bleed)
- postnatal (infection, injury, epilepsy, hypothyroidism)

Question 7

What risk factors are associated with learning disability?

Answer 7

Social and educational deprivation
Low parental intellect

Co-morbid conditions include: epilepsy, autism, cerebral palsy, hearing impairments, visual impairments, psychiatric symptoms, physical disability

Question 8

How common are learning disabilities?

Answer 8

Overall prevalence in the population is 2%. Of these, 80% have mild, 12% moderate and 8% are severe/ profound

Question 9

What presentations in children may suggest learning disability?

Answer 9

Delay in usual development (e.g. sitting up, walking, speaking, toilet training)
Difficulty in managing school work
Behavioural problems

Question 10

Presenting complaints of learning disability in adolescents

Answer 10

Difficulties with peers, leading to social isolation
Inappropriate sexual behaviour
Difficulty in making the transition to adulthood

Question 11

What presenting features may suggest learning disability in adults?

Answer 11

Difficulties in everyday functioning, requiring extra support (e.g. cooking, cleaning, filling in forms, handling money)
Problems with normal social development and establishing an independent life in adulthood (e.g. finding work, marriage and child rearing)

Question 12

Important aspects to assess in suspected cases

Answer 12

Collateral history from family/ carer
Enquire about problems antenatally/ perinatally/ postnatally
Ask about family history of LD
Take a thorough childhood history, including development milestones
Assessment of functioning and life skills
Neuropsychological assessment including IQ
Consider associated problems (epilepsy, neurological and physical disabilities)
Screen for co-morbid psychiatric problems

Conduct fill physical exam, including sight and hearing

Question 13

What are the important aspects of learning disability management?

Answer 13

Multidisciplinary approach
Treat co-morbid medical and psychiatric problems, although unnecessary medication should be avoided (as side effects are common and under reported)
Give information to family and carers about support groups
Behavioural treatments can be used to teach basic skills and alter maladaptive patterns of behaviour
Medication should be used with caution due to limited evidence of efficacy and the increased potential for adverse reactions. Low dose antipsychotics are sometimes used for aggressive or self injurous behaviours

Question 14

Complications associated with learning disability

Answer 14

Higher prevalence of psychiatric symptoms than general population. There can be difficulty in diagnosing psychiatric conditions due to language difficulties and atypical presentations (e.g. schizophrenia may present with simple repetitive hallucinations and persecutory delusions but few 1st rank symptoms; in depression, motor and behavioural changes are more key features than verbal expressions of depressed mood)

Question 15

Autism

Answer 15

A pervasive developmental disorder. 70% of those affected have mild to moderate LD (there is normal IQ in Asperger’s syndrome). Autism is characterised by a triad of features:

1) Language and communication difficulties
2) Abnormal social interaction
3) Restricted and repetitive behaviour, interests and activities

Question 16

Risk factors/ associations for autism

Answer 16

Genetic disorders
Obstetric complications
Infections
Neurological disorders

Question 17

What features in the history may suggest autism?

Answer 17

Onset <36 months. 20% develop autistic features after a period of normal development.

Early symptoms - floppiness, poor eye contact, sluggish feeding

Social impairments - aloofness, lack of interest in people, unresponsive to social cues, poor eye contact, no capacity to share or understand emotions, failure to develop normal attachments

Language abnormalities - distorted and delayed speech and language development, echolalia, stilted rate and rhythm of speech, impaired use of gestures and facial expressions

Stereotyped or ritualised behaviour - hand flapping, rocking, restricted and repetitive behavioural repertoire, insistence on routines, resistance to change, obsessions/ compulsions especially in adolescence

May have isolated exceptional difficulties

Question 18

MSE findings in autism

Answer 18

Appearance and behaviour: ritualised, stereotyped behaviour, poor eye contact, aloof. May attach to unusual items
Speech: delayed speech, echolalia, stilted rate and rhythm of speech, impaired use of gestures and facial expression
Emotions: normal
Perceptions: no abnormalities
Thoughts: obsessions and compulsions
Insight: poor
Cognition: delayed language development

Rating scales such as the Autism Diagnostic Interview (ADI-R) and the Autism Diagnostic Observation Schedule (ADOS) may be used

Question 19

Management of autism

Answer 19

Lifelong disorder
Treat co-morbid problems
Speech therapy to improve language skills
Behavioural approach to challenging behaviours
Social skills training
Education and family support
Educational and vocational interventions
Medications as necessary for symptom management

Question 20

What is Down’s syndrome?

Answer 20

Due to trisomy of chromosome 21 and is the most common genetic cause of learning disability. Although Down’s is diagnosed at birth, the LD becomes apparent by the end of the first year of life with delayed milestones

Full trisomy 21 with non disjunction occurs in 95% of cases. Translocations and mosaicisms account for the other cases

Question 21

Risk factors associated with Down’s syndrome

Answer 21

Maternal age >40 (incidence increases)
Having previous child with Down’s syndrome
Mother with Down’s syndrome

1/3 of adults with Down’s syndrome will have psychiatric illness

Question 22

What are the clinical features of Down’s syndrome?

Answer 22

Protruding tongue
Transverse palmar crease
Up-slanting palpebral fissures
Short stature
Brachycephaly 
Eyes close together 
Maxilla reduced more than mandible 
Under developed bridge of nose 

Diagnosis is made on presence of physical appearance at birth and chromosomal karyotyping

Question 23

Management of Down’s syndrome

Answer 23

As for any causes of learning disability.
In addition, there will be management of physical complications of Down’s syndrome such as:
- congenital cardiac defects
- congenital duodenal stenosis or atresia
- squint
- hearing loss
- hypothyroidism

Question 24

Prognosis of Down’s syndrome

Answer 24

Those who survive into their 40s develop Alzheimer’s disease

Question 25

Fragile X

Answer 25

Learning disability is usually the first feature detected in males with fragile X, and it varies from mild to severe. Common physical features include macro-orchidism (enlarged testes), elongated face, prominent ears, flat feet and high arched palate

Question 26

Phenylketonuria

Answer 26

Autosomal recessive condition
It is an important and preventable cause of severe LD. Caused by deficiency of phenylalanine hydroxylase (long arm of chromosome 12) and is treated by early restriction of dietary phenylalanine. It is diagnosed at birth using the Guthrie test.

Question 27

What is Prader-Willi syndrome?

Answer 27

Caused by a microdeletion on chromosome 15 and results in mild to moderate LD. Other clinical features include over eating, sleep disorders, self injurious behaviour and speech abnormalities

Question 28

Velocardiofacial syndrome

Answer 28

Occurs in 1 in 4000 live births and most patients have a microdeletion in chromosome 22. Over half of patients with the syndrome have LD, which is usually mild to moderate. There is also an association with schizophrenia and affective psychoses. There are cardiac abnormalities (such as Tetralogy of Fallot) and a characteristic facial appearance: receding jaw, wide spaced eyes, midface hypoplasia and ear abnormalities