Intellectual Disability Flashcards
What are the three main features of intellectual disability?
- Significant impairment in intellectual functioning (IQ <70)
- Significant impairment in adaptive behaviour (>2SDs below mean)
- Evidence in the developmental period (under 18)
What is mild ID?
▪️ IQ 2-3 SDs below mean (55-70)
▪️ ~80% of ID, often not diagnosed
▪️ Independence in self care, practical and domestic skills
▪️ Basic reading and writing
What is moderate ID?
▪️ IQ/adaptive behaviour 3-4 SDs below mean (40-55)
▪️ ~10-12%
▪️ Limited language skills, need help wit self-care
▪️ Majority have identifiable organic aetiology
What is severe ID?
▪️ IQ/adaptive behaviour >4 SDs below mean (<40)
▪️ ~4-7%
▪️ Use of words/gestures for basic needs
▪️ Motor impairment
▪️ Can undertake simple tasks and engage in limited social activities
What is profound ID?
▪️ IQ/adaptive behaviour >4 SDs below mean
▪️ 1-2%
▪️ No self care skills
▪️ Some may eventually acquire some simple speech and social behaviour
▪️ Organic aetiology clear in most
What conditions are excluded from ID?
▪️ Educationally disadvantaged people
▪️ Brain injury in adulthood
▪️ Progressive neurological conditions
▪️ Cognitive decline due to severe mental illness/ substance misuse
What are some of the major causes of ID?
▪️ Down syndrome
▪️ Neural tube defects
▪️ Foetal alcohol syndrome
▪️ Fragile X syndrome
▪️ Perinatal factors (e.g., hypoxia)
▪️ Iodine deficiency
▪️ Congenital hypothyroidism
▪️ Genetic disorders such as tuberous sclerosis, PWS, Angelman etc
▪️ Phenylketonuria
What are copy number variants?
▪️ Chromosomal deletions or duplications
▪️ Can be de novo or inherited
▪️ Pathogenic ones are rare but can have large effect sizes
▪️ Presence in neurodevelopmental genes can have adverse functional consequences (e.g, deletion = produce lower quantities of protein)
How can you test for CNVs?
Chromosomal microarray analysis
Can CNV testing be used for diagnosis in ID?
▪️ Can identify significant regions but no information on point mutations
▪️ Diagnostic yield = 15-20%
▪️ Mainly used for research and testing in children (not adults!)
What percentage of ASD can be attributed to CNVs?
10-20%
(e.g., 16p11.2, exonic NRXN1 deletions)
What is the commonest known genetic cause of schizophrenia?
VCFS/22q11.2 deletion
(VCFS = velocardiofacial syndrome)
How might CNV microarrays be used in psychiatric clinics?
To identify undiagnosed genetic conditions in those with MH
What is the most common observation in the investigation of pathogenic CNVs in ID?
CNVs at recurrent loci (55%)
Followed by very rare CNVs (28%) and chromosomal abnormalities (17%)
How might a CNV effecting just one gene be pathogenic?
If that gene is very important for neurodevelopment
Size is not necessarily indicative of effect
What might an individual present with if they have a CNV deletion at recurrent loci (16p11.2)?
▪️ Autism
▪️ Developmental delay
▪️ Large head circumference
▪️ Risk of obesity
What might an individual present with if they have a CNV duplication at recurrent loci (16p11.2)?
▪️ Schizophrenia
▪️ Autism
▪️ Developmental delay
▪️ Small head circumference
▪️ Clinically underweight
What is the most widespread single-gene cause of autism and inherited cause of ID among boys?
Fragile X syndrome (FMR1 gene)
What is the most common genetic cause of ID that is NOT inherited?
Down syndrome (trisomy 21)
What other conditions are individuals with Down syndrome at increased risk of?
▪️ Early onset dementia (AD)
▪️ Depression
▪️ Epilepsy - biphasic due to increased risk in childhood and later on with AD
▪️ Congenital cardiac conditions
▪️ Diabetes and hyperthyroidism
▪️ Sleep apnoea
What is Prader-Willi syndrome and how does it present?
▪️ Loss of paternal chromosome 15 material
▪️ Insatiable appetite, obesity, pica, skin picking
▪️ Increased risk of depression, psychosis, behavioural disorders, OCD symptoms
What is Angelman syndrome and how does it present?
▪️ Loss of maternal chromosome 15 material
▪️ Happy presentation - laughter, clapping etc
▪️ Epilepsy in 90%
▪️ Severe/profound ID
▪️ Fair hair, blue eyes, microcephaly, and long face
What is Lesch-Nyhan syndrome and how does it present?
▪️ X-linked recessive disorder of purine metabolism (very rare!)
▪️ Microcephaly and ID
▪️ Choreoathetosis (slow involuntary movements)
▪️ Seizures, hyperuricaemia
▪️ Severe, compulsive self-injurious behaviour such as biting fingers or lips
What is 22q11.2 deletion syndrome?
▪️ Microdeletion in 22q11.2 region
▪️ Majority spontaneous (10% AD)
▪️ Overlapping phenotypic variations with Di George and VCFS
▪️ Hypocalcaemia and seizures
▪️ 50% have ID, typically mild
▪️ Verbal IQ > performance IQ
What is tuberous sclerosis and how does it present?
▪️ Condition causing calcified benign tumours, particularly in cortex, and skin malformations
▪️ Seizures in 90%
▪️ ID in 2/3
▪️ Behavioural problems, autism, psychotic disorders, self-injurious behaviour
▪️ Treated with everolimus
How does risk for mental health problems differ in those with ID compared to the general population?
▪️ Increased risk (10-39%)
▪️ Particularly for anxiety and affective disorders
▪️ Increased risk of schizophrenia in mild ID
▪️ Comorbidities with ASD, ADHD, and epilepsy
▪️ Behavioural and personality disorders
▪️ Dementia in later life
What are the main issues with estimating the epidemiology of mental health in ID?
▪️ Conflicting/inconclusive research
▪️ Hard to test
▪️ Unknown validity of diagnostic criteria
▪️ Difficult to detect mild ID
What biological factors may contribute to the increased risk of MH in ID?
▪️ Genetic conditions (e.g., PWS, VCFS) - maladaptive behaviours
▪️ Brain injury (e.g., hypoxia)
▪️ Physical disability and sensory deficits
▪️ Speech difficulties
▪️ Epilepsy (20-25%)
▪️ Abnormal thyroid function
▪️ Medication
What potential causes of ID are associated with an increased risk of epilepsy?
▪️ Down syndrome
▪️ Fragile X
▪️ Angelman syndrome
▪️ Rett syndromes
What physical health problems are frequently associated with ID?
▪️ Higher levels of chronic ill health and premature death
▪️ High risk of infection
▪️ Preventable mortality and health inequalities
▪️ Poor uptake of preventative screenings
▪️ DNR notices
What psychological factors associated with ID may contribute to poorer MH outcomes?
▪️ Impaired intelligence and memory
▪️ Lower threshold for stress tolerance
▪️ Impaired or learned dysfunctional coping strategies
▪️ Impaired problem-solving
▪️ Lifelong dependency on others - vulnerable to abuse
▪️ Poor self-image
What environmental factors may contribute to poorer MH outcomes in ID?
▪️ Under or over stimulating environment
▪️ Stigma and social exclusion
▪️ Increased rates of physical/sexual abuse
▪️ Financial exploitation
▪️ Poor supports/relationships
▪️ Carer stress
How might social disadvantage contribute to poorer MH in ID?
▪️ Families more likely to live in poverty
▪️ Social disadvantage continues in adult life
▪️ Multiple social difficulties
What is the DC-ID?
A diagnostic criteria used for psychiatric diagnoses in people with ID, complementary to the ICD-10
Why might people with ID have an increased risk of dementia (~3x)?
▪️ Down syndrome and triple APP gene = increased risk of EOAD from age 40
▪️ Increased rates of depression, hypothyroidism, and behavioural problems
▪️ Social isolation?
How does schizophrenia in ID differ from the general population?
▪️ Rate = 3x higher
▪️ Earlier age of onset
▪️ Content of delusional beliefs is simpler
▪️ Odd behaviours, idiosyncratic speech
▪️ Thought disorder less common
What is the main issue with diagnosing schizophrenia in ID?
Distinguishing hallucinations from developmentally appropriate phenomena such as speaking to oneself or ‘imaginary friends’
How does depression typically present in ID?
▪️ More common, likely associated with physical illness and adversity
▪️ Self-injurious and destructive behaviours
▪️ Atypical presentations such as hypersomnia and increased appetite
How might depression present in severe ID?
▪️ Screaming
▪️ Aggression
▪️ Self-injurious behaviour
How might bipolar disorder present in ID?
▪️ More commonly rapid cycling
▪️ Predominantly irritable
▪️ Possibly related to physical factors such as menstrual cycle
What are the main issues with diagnosing personality disorder in ID?
Can be particularly difficult due to significant symptom overlap with other psychiatric and behavioural disorders
Of the two subtypes of emotionally unstable personality disorder, which is most common in ID?
Impulsive
What are challenging behaviours?
▪️ Culturally abnormal behaviour
▪️ Physical safety of the person or others is at risk
▪️ Or which is likely to limit use of ordinary community facilities (or lead to person being denied use)
What are examples of challenging behaviours?
▪️ Demanding behaviour
▪️ Verbal aggression
▪️ Physical aggression
▪️ Destructiveness
▪️ Self-injurious behaviour
▪️ Absconding
▪️ Stripping in public
What factors should be considered if someone with ID is engaging in challenging behaviours?
▪️ Physical ill-health
▪️ Epilepsy
▪️ Autism
▪️ Communication and sensory difficulties
▪️ Environmental factors
▪️ Abuse
▪️ Maltreatment
When can detention under the Mental Health Act be enforced in individuals with ID?
If someone with intellectual impairment has seriously irresponsible or abnormally aggressive behaviour
BUT controversial
What is diagnostic overshadowing?
The tendency for clinicians to overlook symptoms of mental health in the presence of another condition, such as learning disability
Attribute behaviours to ID
What should be monitored when assessing MH problems in ID?
▪️ ‘Baseline’ measurements
▪️ Sleep
▪️ Appetite and weight
▪️ Level of activity
▪️ Particular behaviours
▪️ Physical examination
What should you consider when asking questions to people with ID?
▪️ Check for suggestibility or acquiescence
▪️ Avoid leading questions
▪️ Use simple, short sentences
▪️ Ask for feedback to ensure comprehension
What are the main standardised instruments for assessing the health of people with ID?
▪️ HoNOS-LD (Health of the Nation Outcome Scales for People with LD)
▪️ PAS-ADD (Psychiatric Assessment Schedule for Adults with Developmental Disabilities)
▪️ DSQIID (Dementia Screening Questionnaire for Individuals with ID)
▪️ CANDID (Camberwell Assessment of Needs for Adults with Developmental and Intellectual Disabilities)
▪️ Behavioural rating scales
What is the multi-axial system for diagnosis using the DC-LD?
- Degree of ID and impairment of behaviour
- Medical conditions, including genetic syndromes
- Psychiatric diagnoses including developmental disorders
What are the main approaches to intervention for ID?
▪️ Medication
▪️ Psychological treatments
▪️ Behavioural treatments
▪️ Environmental and social supports
What are the main issues surrounding the use of medication in ID?
▪️ Historically inappropriate and excessive
▪️ Lack of controlled research
▪️ Capacity and consent
▪️ Most not licensed for behavioural problems
▪️ Drug interactions?
What medication is licensed for controlling aggressive behaviour or intentional self harm in LD?
Lithium
What medication has shown benefit for the treatment of repetitive self-injurious behaviours in LD?
Naltrexone
How can psychological interventions be used in ID?
▪️ Adaptation of CBT models with non-verbal material, drawing, role play etc
▪️ Psychodynamic approaches
▪️ Beneficial also for families and staff
How can behavioural management be used in ID?
▪️ Functional analysis to asses meaning of challenging behaviours
▪️ “Positive behavioural support”
▪️ Non-aversive interventions
▪️ Teaching new behaviours
▪️ Changing environment
What social and environmental factors need to be considered when supporting someone with ID?
▪️ Housing situation
▪️ Ability to self care
▪️ Activities of daily living
▪️ Social opportunities
