Neurodevelopment disorders part 1.2 Flashcards
Intellectual Disability:
Used to be known as Mental Retardation
Intellectual Disability: ICD
“A reduced level of intellectual functioning resulting in diminished ability to adapt to the daily demands of the normal social environment”
Global ability, not specific impairments, should be the basis of the diagnosis
Intellectual Disability: Epidemiology
1-2% of the population
1.5 - 2x more common in males
Majority classified as mild
Mild Intellectual Disability is more common in lower socioeconomic strata, but more severe ID is more evenly distributed among social classes
Intellectual Disability: Statistics
Large majority of individuals live outside of state run institutions. Most live in small group home/supervised living or with family
While life expectancy remains lower than the general population, more individuals with intellectual disability are living into old age
Intellectual Disability: Diagnostic Criteria
Subnormal intellectual functioning
Adaptive deficits
Onset during the developmental period
Intellectual Disability: Subnormal intellect
Defined as IQ score more than two standard deviations below the mean (below 70)
Corresponds to below the 2nd percentile
IQ scores from 70-79 are categorized as borderline
Intellectual Disability: Adaptive deficits
Failure to develop age-appropriate skills in important areas of functioning Communication Self-care Social and interpersonal skills Health Work Safety
Intellectual Disability: DSM-5
Focused more on description of functioning than particular numbers Domains: Conceptual Social Practical
Intellectual Disability: Onset
During the developmental period, meaning before age 18
In practice, onset assumed much earlier
Later onset would be classified as a dementia
Intellectual Disability: Causation - General Points
Intellectual Disability is a syndrome, not a disease - Final common outcome for many conditions
Effects are a function of the timing and duration of insult and extent of CNS exposure
More severe cases are more likely to involve an identifiable cause.
Cases without an identifiable cause are more likely to be mild
Intellectual Disability: Prenatal: Genetic Disorders
Chromosomal aberrations
Downs syndrome
Trisomy 21
Prader-Willi syndrome
Fragile X
Intellectual Disability: Down Syndrome (trisomy 21)
Variety of physical stigmata 1/700 births Moderate or severe retardation typical Many do not live past 40 Often placid and adaptive in childhood Neural plaques and neurofibrillary tangles
Intellectual Disability: Prader-Willi
Small deletion on chromosome 15 Less than 1/10,000 Compulsive eating behavior, obesity Hypogonadism, small stature, small hands and feet Children often oppositional-defiant
Intellectual Disability: Fragile X
1/1000 males, 1/2000 females
Females often less impaired
Degree of Intellectual Disability can be mild to severe
High rates of ADHD, autism
Rapid perseverative speech
Most common inherited form of Intellectual Disability, 2nd most common genetic form after Down syndrome
Intellectual Disability: Phenylketonuria
“paradigmatic inborn error of metabolism”
Inability to convert phenylalanine to paratyrosine because of absence or inactivity of phenylalanine hydroxylase
Disability tends to be severe
Diet control improves behavior and developmental progress- can be normal IQ
Intellectual Disability: Prenatal Causes-External: Maternal infections
Rubella HIV Cytomegalovirus Toxoplasmosis Herpes Symplex Syphilis
Intellectual Disability: Prenatal:External
Toxins/Teratogens
Maternal substance abuse
Alcohol
Cerebral anoxia
Intellectual Disability: Fetal Alcohol Syndrome
The most common preventable cause is in utero alcohol exposure
Intellectual Disability: Perinatal Causes
Infection Meningitis Encephalitis Trauma Cerebral hypoxia
Intellectual Disability: Postnatal Causes
Infections
Meningitis
Encephalitis
Toxins
Lead poisoning
Intellectual Disability: Mild Intellectual Disability
IQ score 55-69, about 85% of cases
May be able to hold a job, learn to read and write, complete high school in special education classes
May function independently but need assistance and guidance when facing unusual social or economic stress
Intellectual Disability: Mild Intellectual Disability: Descriptions`
Language development slower than normal, but will be functional
Self-care skills also slower to develop
Disabilities evident in school, often when diagnosis is made
Learn basic skills at around 6th grade level
Disabilities may interfere with some social roles or activities (e.g., marriage)
Intellectual Disability: Severe and Profound Intellectual Disability
IQ scores 20-35 (Severe) and below 20 (Profound) - Total about 5% of cases
Will usually require institutional care
Limited or no language
Motor impairments more clearly showing CNS damage/maldevelopment
