Psychiatry - Psychiatry of learning disability Flashcards
What is the definition of a learning disability?
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
Features of mild learning disability
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
Moderate learning disability
IQ 35-49
Presents 3-5 years of age
Able to do simple work with support, needs guidance or support in daily living
Severe learning disability
IQ 20-34
Presents before 2 years of age
Requires help with daily tasks and capable of only simple speech
What is profound learning disability?
IQ <20
Presents before 2 years of age
Very disabled in all aspects
Aetiology of learning disability
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)
What risk factors are associated with learning disability?
Social and educational deprivation
Low parental intellect
Co-morbid conditions include: epilepsy, autism, cerebral palsy, hearing impairments, visual impairments, psychiatric symptoms, physical disability
How common are learning disabilities?
Overall prevalence in the population is 2%. Of these, 80% have mild, 12% moderate and 8% are severe/ profound
What presentations in children may suggest learning disability?
Delay in usual development (e.g. sitting up, walking, speaking, toilet training)
Difficulty in managing school work
Behavioural problems
Presenting complaints of learning disability in adolescents
Difficulties with peers, leading to social isolation
Inappropriate sexual behaviour
Difficulty in making the transition to adulthood
What presenting features may suggest learning disability in adults?
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)
Important aspects to assess in suspected cases
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
What are the important aspects of learning disability management?
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
Complications associated with learning disability
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)
Autism
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
Risk factors/ associations for autism
Genetic disorders
Obstetric complications
Infections
Neurological disorders
What features in the history may suggest autism?
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
MSE findings in autism
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
Management of autism
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
What is Down’s syndrome?
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
Risk factors associated with Down’s syndrome
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
What are the clinical features of Down’s syndrome?
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
Management of Down’s syndrome
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
Prognosis of Down’s syndrome
Those who survive into their 40s develop Alzheimer’s disease
Fragile X
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
Phenylketonuria
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.
What is Prader-Willi syndrome?
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
Velocardiofacial syndrome
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
