Autism psych 127c

Definitions

• Intellectual disability: significant limitations in intellectual functioning and adaptive behavior that begin before age 18

• Pertains to limitations in intellectual functioning/adaptive behavior

Intelligence

• Purpose of IQ Tests

  • Used to identify school children who might need special help in school

• Defining and measuring children’s intelligence and adaptive behavior:

  • Alfred Binet and Theophile Simon were commissioned by French government to develop the first intelligence tests to measure judgment and reasoning of school children

• General intellectual functioning is now defined by an intelligence quotient (IQ or equivalent) based on standardized assessments

WISC-V Scales

• Verbal Comprehension Index

  • Vocabulary, Similarities

• Visual Spatial Index

  • Block design, Puzzles

• Fluid Reasoning Index

  • Matrix reasoning, Figure weights

• Working Memory Index

  • Digit span, Picture span

• Processing Speed Index

  • Coding, Symbol Search

Flynn Effect

• IQ scores have gone up about 3 points every 10 years

• Reasons unclear but may reflect some actual gains

• Tests are now re-normed every 15 to 20 years

  • Downside is that test scores drop for those with borderline or mild intellectual disabilities

Functional Impairment

• ID is not defined solely on the basis of IQ; one’s level of adaptive functioning is important

• Adaptive functioning: how effectively individuals cope with ordinary life demands and how capable they are of living independently and abiding by community standards

IQ Distribution

• 50% are between 90 and 110 

• 95% are between 70 and 130

  • Not true 

• 2.5% are between less than 50 and 70

• SD is 15

• Average is 100

• Separate distribution (organic) plays a role in calcultaing 

• Two IQ distributions at play 

Clinical Description

• Clinical Description

  • Considerable range of abilities and interpersonal qualities

  • DSM-5 Diagnostic criteria 

    • significantly subaverage IQ (70 or below) 

    • concurrent deficits or impairments in adaptive functioning

    • below-average intellectual and adaptive abilities must be evident prior to age 18

• A label of ID has serious ramifications, including placement in school learning environment

Mild Intellectual Disability

• IQ of 55 to 70 

• about 85% of persons with ID

• typically not identified until elementary school years

• overrepresentation of minority group members

• develop social and communication skills; possibly moderate delays in expressive language 

• with appropriate support, as adults, they usually live successfully in the community

Moderate Intellectual Disability

• IQ of 40 to 54

• about 10% of persons with Intellectual Disability

• usually identified during preschool years

• applies to many people with Down syndrome

• benefit from vocational training and in adulthood can meaningfully perform supervised unskilled/semi-skilled work

Severe

• IQ of 25 to 39

• about 3%-4% of persons with Intellectual Disability

• often associated with organic causes

• usually identified at a very young age due to delays in developmental milestones

• between ages 13-15, their academic and adaptive abilities are similar to an average 4-6-year-old

• may have mobility and health-related problems

• need special assistance throughout their lives; adapt well to living in group homes or with their families

Profound

• IQ below 25

• about 1%-2% of persons with Intellectual Disability

• usually identified in infancy due to marked delays in development and biological anomalies

• learn only the rudiments of communication skills and require intensive training to learn eating, grooming, toileting, and dressing behaviors

• require lifelong care and assistance

• almost always associated with organic causes and often co-occurs with severe medical conditions

Issues

• Level of Needed Supports

  • DSM categories criticized as stigmatizing and limiting because they emphasize degree of impairment

• AAIDD focuses on level of support or assistance needed (rather than on IQ):

  • Intermittent

  • Limited

  • Extensive

  • Pervasive

• Emphasis on interaction between person and environment to determine level of functioning

AAIDD Categories of Needs

• Teaching and Education

• Home Living

• Community Living

• Employment

• Health and Safety

• Behavioral

• Social

• Protection and Advocacy

Sex Distribution

• Twice as many boys as girls (2:1)

  • Ratio is to 1.5:1.0 for those with more severe forms

  • Not clear if this is due in part to referral bias (boys more likely to be identified and referred for help)

Developmental Course

• Developmental Viewpoint

  • Similar sequence–pass through intellectual development in an invariant sequence

  • Similar structure–similar behaviors and underlying processes as typically developing children of different age

• Difference Viewpoint

  • Differences more than developmental rate or upper limit

  • Different reasoning and problem-solving strategies

• Best evidence so far favors Developmental Viewpoint

Other Disabilities (Comorbidity)

• 12% of children with mild Intellectual Disability and 45% with moderate to profound Intellectual Disability have at least one other disability, such as sensory impairments, cerebral palsy, and epilepsy

• Chance of other disability increases as degree of intellectual impairment increases

Origins 

• Over 1,000 genetic disorders associated with ID, in addition to other organic causes

• Children inherit a genotype, which expresses in a given environment as a phenotype, which can be related to ID

Chromosomal Influences and Single Gene Influences

• Down syndrome 

  • failure of the 21st pair of the mother’s chromosomes to separate during meiosis, causing an additional chromosome (trisomy 21) – risk increases with maternal age

• Physical abnormalities, mild ID

• Fragile-X syndrome, the most common cause of inherited Intellectual Disability, is associated with the FMR-1 gene

• Fewer physical abnormalities than Down, mild to mod ID

• Prader-Willi and Angelman syndromes both associated with abnormality of chromosome 15; believed to be spontaneous genetic birth defects occurring around the time of conception

Single-gene conditions can result in excesses or
shortages of chemicals necessary for different stages
of development
 Account for 3-7% of cases of severe Intellectual
Disability
 One of the best understood is phenylketonuria,
(PKU)
 lack of liver enzymes necessary to metabolize
phenylalanine
 it can be successfully treated by screening and diet

Environmental Influences

Prenatal exposure to toxins, trauma, alcohol can affect
nervous system development
 Fetal alcohol spectrum disorder (FASD) covers a range
of outcomes
 Even small amounts have large impact
 FAS – central nervous system dysfunction, facial
abnormalities, physical growth in the 10 th percentile
 Mechanisms not entirely clear

Prevention and Treatment

Prenatal screening
 Early intervention – especially helpful in preschool
years (can see gains of 5 IQ points)
 Behavioral interventions
 Modeling, rehearsal, shaping
 Parenting strategies
 Self-instructional techniques
 Similar to self-verbalization strategies with ADHD

Autism Spectrum

• Autism spectrum disorders (autism):
  developmental disorders characterized by
  abnormalities in social functioning, language and communication, and stereotyped patterns of behaviors and interests

Autistic Disorder

Impairments in social interaction
 Impairments in communication
 Restricted repetitive and stereotyped patterns of behavior, interests, and activities
 Delays or abnormal functioning in social interaction, social communication, or symbolic or imaginative play prior to age 3

Social Impairments

deficits in social and emotional reciprocity
 unusual nonverbal behaviors (e.g., atypical facial
expressions)
 lack of interest and/or difficulty relating to others
 failure to share enjoyment/interests with others
 social imitation, joint attention, make-believe play
 limited social expressiveness and sensitivity to social cues
 deficits in recognizing faces/facial expressions

Communication Impairments

Half don’t develop useful language
 Those who do, learn between 12 and 30 months
 Qualitative language impairments:
 Pronoun reversals
 Echolalia
 Perseverative speech
 Impairments in pragmatics (appropriate use of language in social contexts)

Inconsistent use of early preverbal communications
 Protoimperative gestures (OK): used to express needs
 Protodeclarative gestures (poor): used to direct attention
 Infrequent use of “show” gestures
 Better at instrumental (“stop”) gestures than
expressive/emotion (“look sad”) gestures to convey feelings

Protodeclarative Gestures and Joint
Attention

Illustrations of different types of infant social attention coordination behaviors:
(a) Responding to Joint Attention: involving following another person’s gaze and pointing gestures;
(b) Initiating Joint Attention involving a conventional gesture; (c) IJA involving alternating eye contact

Other Impairments

Repetitive and stereotyped behaviors and narrow
patterns of interest
 Stereotyped body movements
 Self-stimulatory behavior (e.g., hand flapping)
 Different theories to explain self-stimulatory behaviors:
 a craving for stimulation to excite their nervous system
 a way of blocking out/controlling unwanted stimulation from environment that is too stimulating
 it is reinforcing

Intelligence and Autism

About 70% of children with autism have co-occurring intellectual impairment
 about 40% have severe to profound impairments (IQ<50)
 30% have mild to moderate impairments (IQ 50-70)
 30% have average intelligence or above
 although the performance of children with autism is uneven across WISC subtests, a common pattern is low verbal/high nonverbal scores; WISC scores are lower than on other tests of intellectual functioning
 about 25% have splinter skills/islets of ability; and 5% (autistic savants) display isolated, remarkable talents

Schizophrenia

Positive Symptoms
 Hallucinations
 Delusions
Negative Symptoms
 Slowed speech, movement
 Indifference to social contact
 Harder to treat

Extremely rare in children < 12 (modal onset between 20 and 25)
 95% show history of some disturbance prior to onset
 Highly familial, but not 100%
 About 70% have comorbid disorders