Lecture 2 - Intellectual Disability

what are the different developmental milestones?

language and communication, socializing, problem solving and physical skills like being able to feed yourself

global developmental delay

this occurs when there are delays in 2 or more developmental milestone domains, this has to occurs at less than 5 yrs of age

what is considered a significant delay?

if the delay is 2 standard deviations below the mean

motor and cognitive function

this is affected by problem solving and physical domains, if there are delays in these areas checking vision is important cause there may be issues in visual motor integration

what happens if a 9 month old doesn’t babble?

it is worrisome as it could be an indicator of a language disorder, it could also impact verbal working memory

what happens if a 1 yr old doesn’t point?

it could indicate autism as this impairment means executive functioning is impacted which is a key feature of autism

what happens if an 18 month old only uses 2 words?

a boost in vocabulary is usually supposed to happen at 14 month old so if there isn’t that boost you would need to investigate comprehension via routine words as usually by this age a child should be producing around 25 words

Binet and Simon Study

they wanted to identify children who may need special help in school leading them to develop the IQ test, they used judgement and reasoning tasks to see if the child can keep up with typical societal demands

IQ test parameters

100 is the average score, there needs to be a consideration for exact change and gender of these norms, the SD is 15 and there is usually some error, some kids are more likely to make mistakes than others so there are subtest indices for them, the rough score will get changed to a skill score then you find an average of what is expected for

what is the cut-off to indicate that someone has an intellectual disability?

an IQ score of 70, if it is between 65 and 70 the person meets the 1st criteria for it

the Flynn effect

the phenomenon that IQ scores have risen about three points per decade, to account for this discrepancy the scales are normed frequently

what are the limitations for IQ testing in specific populations?

they don’t take into account sensory, motor or language deficits, individuals with intellectual disability typically have not received the type of exposure to test environments that other individuals have, there is also underdiagnosis in girls with mild intellectual disability

the controversial IQ

it is relatively stable over time except for when it is measured in children before school age, mental ability is also always modified by experience

intellectual disability

a disorder with onset during the developmental period that includes both intellectual and adaptive functioning deficits in conceptual, social and practical domains

mild intellectual disability

when IQ score is between 50/55 to 70, intellectual age would correspond to 7/8 to 12, this represents 85% of people with ID, they are usually not identified until early elementary, there is an overrepresentation of minority group members, they can develop social and communication skills but also live successfully in the community as adults with appropriate supports

moderate intellectual disability

when IQ score is between 35/40 to 50/55, corresponds to an intellectual age of 4/5 to 7/8, this represents 10% of people with ID, it is usually identified during preschool, it applies to many people with down syndrome, they benefit from vocational training and can perform supervised unskilled or semiskilled work in adulthood

severe intellectual disability

when IQ score is between 20/25 to 35/40, which corresponds to an intellectual age of 2 to 4/5, it represents 3-4% of people with ID, it is usually associated with organic causes, it is identified at a very young age due to delays in developmental milestones but also visual features, this may cause mobility or other health issues requiring special assistance and might live in group homes or with family for the rest of their lives

profound intellectual disability

when IQ score is up to 20/25, indicates an intellectual age of 0 to 2, this represents 1/2% of people with ID, it is identified in infancy due to marked delays in development + biological abnormalities, limits communication skills, they need intensive training for eating, grooming, toileting and dressing behaviors, need lifelong care and assistance

what are deficits in intellectual functions that characterize intellectual disability?

issues with reasoning, problem-solving, planning, abstract thinking, judgment, academic learning and learning from experience, this has to be confirmed by clinical assessment and individualized, standardized intelligence testing

what are deficits in adaptive functioning that characterize intellectual disability?

deficits have to result from failure to meet developmental and sociocultural standard for personal independence and social responsibility, also has to be without ongoing support, the deficits have to limit functioning in one or more activities of daily life like communication social participation and independent living across multiple environments like home, school, work and community

how has the definition of intellectual disability changed?

now it reflects not only the level of IQ but also deficits in adaptive behavior, the description of one’s level of functioning should be contextualized

conceptual skills (adaptive behavioral skills)

receptive and expressive language, reading and writing, money concepts

social skills (adaptive behavioral skills)

interpersonal, responsibility, gullibility and obeys laws, intellectual disability in this regard would be like not waiting for your turn cause you cant inhibit your own desires to respect the social rules of a game for example

practical skills (adaptive behavioral skills)

personal activities like eating, dressing, mobility and toileting, instrumental activities like preparing meals, using the telephone, managing money and using transportation

occupational skills (adaptive behavioral skills)

maintaining a safe environment

prevalence of intellectual disability

twice as many males compared to females have mild cases of ID (but remember underdiagnosis in females), it is more prevalent in children with low SES or minority groups, more severe levels are identified equally among economic and racial groups

ID changes

IQ scores are able to fluctuate in relation to the level of impairment, a major cause of the disorder is the degree to which IQ and adaptive abilities may change

slowing and stability hypothesis

refers to the idea that individuals with developmental disabilities tend to exhibit a pattern of development where periods of significant learning and progress interspersed with extended periods of minimal advancement, suggests a slower overall developmental trajectory with increased stability in their abilities over time compared to typically developing individuals

the case of down syndrome

IQ of children with this disorder may plateau during middle childhood then decrease over time, characteristic features include the underlying symbolic abilities of children to stay pretty much intact, there is a considerable delay in expressive language development and it is weaker than receptive language

emotional and behavioral problems

disorders of this nature consist of impairments in impulse control, anxiety, and mood, internalizing problems and mood issues are common in adolescence, behaviors can also be self-injurious or aggressive

Pica

eating disorder in which a person eats things not usually considered food, this is seen in serious form among children and adults with intellectual disability

causes of moderate to profound ID

genetic of environmental causes are known for 2/3 of individuals

prenatal ID causes

due to genetic disorders and accidents in the womb

perinatal ID causes

due to prematurity and anoxia which is injury caused by decreased oxygen in a particular organ

postnatal ID causes

due to meningitis and head trauma

zigler’s two group approach

it consists of an organic group and a cultural-familial group

organic group

associated with severe and profound ID, parents usually have normal IQ, there are more physical signs of intellectual disability present in the individual, IQ is low and the cause of it is unknown

cultural-familial group

associated with mild ID, there is no clear cause, individual has low to borderline IQ, parents also have borderline IQ and there are no obvious physical anomalies

developmental vs difference course

the debate is if you have an intellectual impairment will you go through the same milestones just at a different rate or not

developmental view point (sequence hypothesis)

with or without ID, the developmental milestone stages are ordered the same

developmental view point (structure hypothesis)

developmental milestones stage progression is in correspondence with mental age

difference view point

might be something specific about their profile and their abilities, some parts more typical and some not, cognitive development of children with ID is qualitatively different in reasoning/problem solving, familial vs organically based ID

Williams Syndrome

caused by an impairment chromosome 7, characterized by low overall intellectual functioning, hyperactivity, impulsivity and inattention (ADHD profile), also poor visual-spatial skills, there is unusual strength in spoken language and sociability so well developed lexicons but exhibits issues with anxiety

Prader Willi syndrome

this is caused by one or two chromosomes 15 from the mom, it causes mild intellectual impairment, tend to overeat and have a food disorder, OCD behaviours, they dont feel satiety due to issue in the hypothalamus, exhibit strong visual spatial skills, weakness in short term memory and adaptive behaviours, more inclined to have psychotic symptoms, present with short stature and obesity but they can be helped by growth hormone visual-spatial

angelman syndrome

caused by chromosome 15 from the father either one or two, causes speech impairment, have a happy demeanor, facial features like larger mouth, pointed chin and thin upper lip, can’t recognize it until toddler, 90% of people with it have seizures, severe reflux, screaming, very sociable and interested in people

Down Syndrome

caused by an extra chromosome 21, it is rare to have a case that it is inherited as it is usually due to random mutation during early cell division, risk of getting increased with parents age, it can lead to moderate or severe deficits in language, verbal comprehension, expressive language, reading and writing, they are relatively strong in non verbal problem solving

Di George Syndrome

caused by defect in chromosome 22, it affects 1 in 2000-4000 children, affects the immune system, when it is severe it causes low cognitive functioning and serious health problem, average IQ is 70 so they have high verbal skills compared to non verbal, it is associated with a 50% risk of getting schizophrenia, tendency to be comorbid with ADHD

fragile X syndrome

it is characterized by weakness in site on X chromosome, characterized by number of cognitive behavioral and physical symptoms, 25% of males with the syndrome also meet the criteria for autism, it caused by a mutation of the FMR1 gene, it usually makes a protein that helps brain development, it is more common in boys than in girls, children with more repeated sequences will have more severe cognitive impairments, shows ADHD symptoms, anxiety and autistic behaviors

single gene conditions

this is due to inborn errors of metabolism, it causes excesses or shortages of certain chemicals which are necessary during child development, cause of 3-7% of cases of severe ID

phenylketonuria

results in lack of liver enzymes necessary to metabolize phenylalanine, it can be treated successfully

adverse biological conditions

infections like rubella and zika, traumas and accidental poisonings during infancy and childhood

fetal alcohol syndrome disorder

lifelong condition that occurs when a developing fetus is exposed to alcohol, estimated to occur in one ½ to 2 per 1000 live births, facial characteristics include small eye openings, smooth philtrum and thin upper lip

teratogens

a substance that can cause birth defects or increase the risk of miscarriage, preterm labor or still-birth, it increases the risk of ID