Introduction to Intellectual Disability Flashcards
What are Intellectual Disabilities?
-Significant impairment in intellectual functioning (IQ <70)
-Significant impairment in adaptive behaviour (> 2 SDs below mean on tests of adaptive behaviour)
-Evidence of 1 and 2 in the developmental period (i.e. under 18 years old)
What is mild ID? (ICD-11)
IQ: 2-3 SDs below mean
-Over 80% of ID population
-independence in self care, practical domestic skills
-basic reading/writing
-most people never diagnosed
-may need help with housing and employment or when under unusual stress
What is moderate ID?
IQ/ adaptive behaviour: 3-4 SDs below mean
-limited language skills
-need help with self-care
-about 10-12% of the ID population
-Majority have identifiable organic aetiology
What is severe ID?
IQ/ adaptive behaviour: > 4 SDs below mean
-Use of words/gestures for basic needs
-motor impairment & others are common
about 4-7%
-can undertake simple tasks and engage in limited social activities
What is profound ID?
IQ/ adaptive behaviour: > 4 SDsbelow mean
-1-2% of the ID population
-some eventually acquire some simple speech and social behaviour
-no self care skills
-Organic aetiology is clear in most
What proportion of people have intellectual disabilities?
Intellectual impairment ~2.5%, ID 1%, Severe ID 0.35%
What conditions are excluded from ID by definition?
-Educationally disadvantaged people
-Brain injury in adulthood
-Progressive neurological conditions in adulthood such as dementia
-Cognitive decline due to severe mental illness/substance misuse
What is the aetiology of ID? can name a few
-Down syndrome
-Neural tube defects
-Perinatal factors
congenital hypothyroidism (neonatal screening)
-Foetal alcohol syndrome
-Iodine deficiency
-Fragile-X syndrome
-Other genetic disorders (PWS / Angelman, Rett syndrome & tuberous sclerosis)
Phenylketonuria, inborn errors of metabolism
Most cases-unknown aetiology
What are copy number variants (CNVs)?
-Submicroscopic chromosomal deletions or duplications
-Typically >1000 bp
-De novo or inherited
-Common vs rare
-CNV in neurodevelopmental genes = more adverse functional consequences
-Associated with ID, Autism and -
-Schizophrenia
CNVs in autism spectrum disorders (ASD)
-Risk for autism first described at the 16p11.2 locus
-Many more CNVs found e.g. exonic NRXN1 deletions (affects neurotransmission)
-CNVs now thought to be the cause of 10-20% of autism cases
copy number variants in schizophrenia
-CNV deletions at chromosomes 1, 15, 22 implicated in Sz
-VCFS/22q11.2 deletion – one of the strongest risk factors for psychosis (~40% of VCFS del carriers)
-Robust contribution of CNV to schizophrenia, loci involved in neurological functions (e.g. postsynaptic density)
Down syndrome (trisomy 21)
-1 in 700 live births
increased risk of early onset dementia (AD), depression
-40% above 50 & 80% lifetime risk in DS for AD
-APP gene triplicated on Chr 21
-Note trisomy, translocations & mosaicism
-Epilepsy 10% in childhood, biphasic prevalence because seizures common in those with AD
What is Prader-Willi syndrome?
-loss of paternal chromosome 15 material
-insatiable appetite, obesity, pica, skin picking
-depression, psychosis behavioural disorders, OCD symptoms
physical characteristics:
-overweight, narrow temple distance and almond shaped eyes, thin upper lip, downturned mouth
What is Angelman Syndrome?
-loss of maternal chromosome 15 material
-Happy presentation with laughter with hand flapping, clapping
-Epilepsy 90%
-Severe/profound ID
-Fair hair, blue eyes (above 60%) microcephaly and long face wide spread teeth
What is Lesch-Nyhan Syndrome?
-X-linked recessive disorder of purine metabolism
-1:380,000 births
microcephaly, ID, choreoathetosis,
-seizures 50%, hyperuricaemia
severe compulsive self-injurious behaviour, biting of fingers and lips
What is 22q11.2 deletion Syndrome?
-microdeletion in 22q11.2 region
-Incidence 1 in 4000-6000 live births.
=Most cases are spontaneous (90%) or autosomal dominant (10%)
-Di George/VCFS/deletion 22 syndrome: overlapping phenotypic variations
Hypocalcaemia 60% seizures
What are the clinical manifestations of 22q11.2 deletion?
-Mean IQ is 70 - 50% will have ID
-Typically Verbal IQ > Performance IQ
-Borderline – mild ID
Elaborate on o22q11.2 deletion & psychosis
-Increased prevalence of OCD, ADHD
-30 % of VCFS sample had psychotic illness (24% schizophrenia) (Murphy et al. 1999)
-Commonest known genetic cause of schizophrenia
-2% of sample with schizophrenia had VCFS (Bassett et al. 1998)
Why the increased prevalence of mental illness? What are some biological factors?
-genetic conditions
-brain injury
-physical disabilities, sensory deficits
-speech difficulties
-14–24% epilepsy
-abnormal thyroid function
-medication
What is the Physical health of people with ID like?
-Higher levels of chronic ill health and premature death
-High risk of infection (common cause of death in e.g. Down syndrome)
-Preventable mortality, health inequalities
-Poor uptake of preventative health screening
-DNR notices
Why the increased prevalence of mental illness? What are some psychological factors?
-Impaired intelligence, memory
-Lower thresholds for stress tolerance/ learned dysfunctional or abnormal coping strategies
-Impaired problem-solving skills and coping mechanisms
-lifelong dependency on others -vulnerability to abuse
-poor self-image
Why the increased prevalence of mental illness? What are some Environmental & social factors?
-Under- or over-stimulating environment
-Stigmatisation / social exclusion
-Increased rates of physical and sexual abuse
-Financial exploitation
-Poor supports / relationships - only 30% has a friend (not paid carer or family member)
-Carer stress
What are some common MH problems & phenomenology?
-Dementia
-Schizophrenia
-Affective disorders
-Anxiety disorders
-Behavioural and personality disorders
-Co-morbid autistic spectrum disorder, epilepsy, ADHD
What re the classification systems used?
-ICD-11, DSM-5
-DC-ID (RCPsych 2001)
diagnostic criteria for use with people with ID - provide operational Dx criteria (complimentary to ICD-10)
Dementia in people with ID
-early onset Alzheimer’s in people with Down syndrome
-rule out depression, hypothyroidism behavioural problems
-establish a ‘baseline’ / document highest level of functioning
What is the prevalence of dementia in people with Down Syndrome?
-Mean age of onset- 54 years
-Other disorders developing:
Seizures-84%
Parkinson’s symptoms - 20%
Schizophrenia & ID
-Rate 3 x higher compared to general population with earlier age of onset
-genetic conditions, most commonly 22q11.2 deletion syndrome
-But some diagnostic issues - Distinguish hallucinations from developmentally appropriate phenomena - speaking to oneself or to ‘imaginary friends’
-Thought disorder are less evident & delusional beliefs simpler in content
-odd behaviors, idiosyncratic speech
Depression in people with ID
-more common, frequently undiagnosed
-physical illness, socioeconomic adversity
-self-injurious or destructive behavior -may dominate the clinical picture
-may present atypically (e.g. hypersomnia and increased appetite)
Bipolar Disorder & ID
-rapid cycling bipolar disorder more common
-mood predominantly irritable rather than euphoric
-cyclical changes in behavior & altered mood in some people with ID and/or autism
-possible other factors, such as physical factors (menstrual cycle in women)
Anxiety disorders & ID
-common but under-reported
-increased risk of OCD in Prader-Willi syndrome
-anxiety when routines are changed in people with autism
-particular vulnerability to PTSD
Personality Disorders
-diagnosis particularly difficult
-significant symptom overlap with other psychiatric and behavioural disorders
-Emotionally unstable PD 2 subtype
borderline/ impulsive subtype (overlap forensic & CB)
What is the triad of impairments in Autistic Spectrum Disorders?
triad of impairments
-verbal and non-verbal communication
-reciprocal social interaction
-imaginative skills and limited interests
What is ‘Challenging Behaviour’?
“Culturally abnormal behaviour of such an intensity, frequency or duration that the physical safety of the person or others is likely to be placed in serious jeopardy, or behaviour which is likely to seriously limit use of, or result in the person being denied access to ordinary community facilities” (Emerson,1995)
What are examples of challenging behaviour?
-Demanding behaviour
-Verbal aggression
-Physical aggression
-Destructiveness
-Self injurious behaviour
-Absconding
-Stripping in public
How should MH problems be assessed in ID?
-complex and challenging process
-different referral pathways
-vulnerability, precipitating and maintaining factors
-coordinated multi-modal and interdisciplinary approach
What is Diagnostic overshadowing?
the tendency of the clinicians to overlook symptoms of mental health problems in this group and attribute behaviours to being part of ‘having a learning disability’
What is Baseline exaggeration?
important to establish a ‘baseline’ of what the person was like, and look for any change from this
What are other important aspects of MH assessment in ID?
-monitoring sleep, appetite and weight, level of activity, particular behaviours
physical examination, investigations
-Risk assessment: risk to self and/or others, risk of self-neglect, abuse and exploitation
-Legal framework: MHA, MCA, DOLS
How should you ask/phrase questions?
-Check for suggestibility, acquiescence
-Avoid leading questions, use closed & contradictory questions as necessary
-Use simple, short sentences; no double clauses, metaphors or idioms
-Ask for feedback to ensure comprehension
What are some standardised instruments & rating scales?
-HoNOS-LD
-Mini PAS-ADD & PAS-ADD checklist
-DSQIID
-Behavioural rating scales
-CANDID
What is the Multi-axial system (DCLD)?
-AXIS I Degree of ID and impairment of behaviour
-AXIS II Medical conditions, including genetic syndromes
-AXIS III Psychiatric diagnoses including developmental disorders
What are some intervention options?
-Medication
-Psychological treatments
-Behavioural treatments
-Environmental and social supports
What should be considered in terms of medication?
-inappropriate and excessive use in the past
-little controlled research
-drug interactions
-capacity & consent issues
-must be part of broader plan
-Most medication is not licensed to treat behavioural problems
-Lithium is licensed for control of aggressive behaviour or intentional self harm
-Naltrexone evidence treatment of repetitive self injurious behaviour
What are some psychological interventions?
-benefits also for families and staff
-adaptation of CBT models with non-verbal materials, drawings, symbols, photographs, role-play
-psychodynamic approaches
What does behavioural management consist of?
-“Positive behavioural support”
-non-aversive interventions
-teaching new behaviours
-changing the environment
-Bespoke care package and structured individualised services
How can social interventions and environmental support be provided?
-Review of the person’s housing situation, ability to self care, ADLs, other support needs, daily activities and social opportunities
