Intellectual Disability and Intellectual Disability and Chromosomal Chromosomal AbnormalitiesAbnormalities

Clinical Science IIIClinical Science III

Karen R. Voogt, DPTKaren R. Voogt, DPT

Fall 2011Fall 2011

Intellectual Intellectual disability disability Preferred over Mental Preferred over Mental

RetardationRetardation

Mental RetardationMental Retardation

DSM IV:DSM IV:

A generalized disorder characterized A generalized disorder characterized by significantly impaired cognitive by significantly impaired cognitive functioning and deficits in 2 or more functioning and deficits in 2 or more adaptive behaviors with onset before adaptive behaviors with onset before age 18.age 18.

Communication, self help, Communication, self help, interpersonal skills, daily living.interpersonal skills, daily living.

DSM IV Mental DSM IV Mental RetardationRetardation

317.0 Mild mental retardation317.0 Mild mental retardation 318.0 Moderate mental retardation318.0 Moderate mental retardation 318.1 Severe mental retardation318.1 Severe mental retardation 318.2 Profound mental retardation318.2 Profound mental retardation 319 Mental retardation, severity 319 Mental retardation, severity

unspecifiedunspecified

Mild MRMild MR

Mild mental retardation Mild mental retardation Approximately 85% of the mentally Approximately 85% of the mentally

retarded population is in the mildly retarded population is in the mildly retarded category. Their IQ score retarded category. Their IQ score ranges from 50–70, and they can ranges from 50–70, and they can often acquire academic skills up to often acquire academic skills up to about the sixth-grade level. They can about the sixth-grade level. They can become fairly self-sufficient and in become fairly self-sufficient and in some cases live independently, with some cases live independently, with community and social support. community and social support.

Moderate MRModerate MR

Moderate mental retardation Moderate mental retardation About 10% of the mentally retarded About 10% of the mentally retarded

population is considered moderately population is considered moderately retarded. Moderately retarded persons retarded. Moderately retarded persons have IQ scores ranging from 35–55. They have IQ scores ranging from 35–55. They can carry out work and self-care tasks with can carry out work and self-care tasks with moderate supervision. They typically moderate supervision. They typically acquire communication skills in childhood acquire communication skills in childhood and are able to live and function and are able to live and function successfully within the community in such successfully within the community in such supervised environments as group homes. supervised environments as group homes.

Severe MRSevere MR

Severe mental retardation Severe mental retardation About 3–4% of the mentally retarded About 3–4% of the mentally retarded

population is severely retarded. population is severely retarded. Severely retarded persons have IQ Severely retarded persons have IQ scores of 20–40. They may master scores of 20–40. They may master very basic self-care skills and some very basic self-care skills and some communication skills. Many severely communication skills. Many severely retarded individuals are able to live retarded individuals are able to live in a group home. in a group home.

Profound MRProfound MR

Profound mental retardation Profound mental retardation Only 1–2% of the mentally retarded Only 1–2% of the mentally retarded

population is classified as profoundly population is classified as profoundly retarded. Profoundly retarded individuals retarded. Profoundly retarded individuals have IQ scores under 20–25. They may be have IQ scores under 20–25. They may be able to develop basic self-care and able to develop basic self-care and communication skills with appropriate communication skills with appropriate support and training. Their retardation is support and training. Their retardation is often caused by an accompanying often caused by an accompanying neurological disorder. Profoundly retarded neurological disorder. Profoundly retarded people need a high level of structure and people need a high level of structure and supervision. supervision.

Causes of Intellectual Causes of Intellectual DisabilityDisability

PrenatalPrenatal

PerinatalPerinatal

PostnatalPostnatal

Causes of Intellectual Causes of Intellectual Disability:Disability:

The three most common causes of The three most common causes of intellectual disability, accounting for intellectual disability, accounting for about 30% of cases, are Down about 30% of cases, are Down syndrome, fragile X, and fetal alcohol syndrome, fragile X, and fetal alcohol syndrome. Males are more likely than syndrome. Males are more likely than females to have MR in a 1.5:1 ratio. females to have MR in a 1.5:1 ratio.

Intellectual DisabilityIntellectual Disability

PrenatalPrenatal Developmental disorders of brain Developmental disorders of brain

formation (hydrocephalus)formation (hydrocephalus) Teratogens (alcohol, radiation)Teratogens (alcohol, radiation) Infection (STORCH)Infection (STORCH) Metabolic DisordersMetabolic Disorders Chromosomal abnormalitiesChromosomal abnormalities

Intellectual DisabilityIntellectual Disability PerinatalPerinatal

Prematurity (intracranial hemorrhage)Prematurity (intracranial hemorrhage) PostnatalPostnatal

Infection (meningitis)Infection (meningitis) Anoxia (near drowning)Anoxia (near drowning) Trauma (shoulder dystocia, vacuum Trauma (shoulder dystocia, vacuum

extraction)extraction) Degenerative disordersDegenerative disorders Seizure disordersSeizure disorders Malnutrition/Environmental deprivationMalnutrition/Environmental deprivation

Intellectual DisabilityIntellectual Disability

Majority of cases (especially mild to Majority of cases (especially mild to moderate)-cause unidentifiablemoderate)-cause unidentifiable

DetectionDetection Performance on cognitive testPerformance on cognitive test Developmental delay as opposed to MR Developmental delay as opposed to MR

<9 year old<9 year old

I.Q.I.Q. ProfoundProfound SevereSevere ModerateModerate MildMild BorderlineBorderline Dull/NormalDull/Normal NormalNormal High averageHigh average Superior Superior Very superior Very superior

< 25< 25 25-3925-39 40-5440-54 55-6955-69 70-8070-80 81-8981-89 90-10990-109 110-119110-119 120-129120-129 130 and ^130 and ^

PrevalencePrevalence Mental Mental

Retardation Retardation 7.8 per 1,0007.8 per 1,000

Development Development DisabilitiesDisabilities 11.3 per 1,00011.3 per 1,000

Combined MR & Combined MR & DDDD 14.9 per 1,00014.9 per 1,000

Movement Impairments in Movement Impairments in Children with Cognitive Children with Cognitive

ImpairmentsImpairments Basis is CNS pathology including:Basis is CNS pathology including:

FlexibilityFlexibility Force productionForce production CoordinationCoordination Postural controlPostural control BalanceBalance Endurance and efficiencyEndurance and efficiency Cardiopulmonary and musculoskeletal Cardiopulmonary and musculoskeletal

impairments may contributeimpairments may contribute

Fragile X SyndromeFragile X Syndrome X-linked dominant disorderX-linked dominant disorder Most common type of inherited Most common type of inherited

cognitive impairmentcognitive impairment FeaturesFeatures

HypotoniaHypotonia Joint hypermobilityJoint hypermobility Delayed motor milestonesDelayed motor milestones Autism spectrum disorderAutism spectrum disorder Elongated facies, large ears, prominent Elongated facies, large ears, prominent

mandiblemandible

Fragile XFragile X

CHROMOSOMAL CHROMOSOMAL ABNORMALITIESABNORMALITIES

Cell Division: Cell Division: Problems with separationProblems with separation

DeletionDeletionTranslocation Translocation NondisjunctionNondisjunction

DOWN SYNDROMEDOWN SYNDROME

INCIDENCEINCIDENCE 1:700 newborns1:700 newborns > in mothers over age 35> in mothers over age 35

1:2000 < 301:2000 < 30 1:50 35-391:50 35-39 1:20 > 401:20 > 40

5-10% related to advance paternal age5-10% related to advance paternal age Lifespan: Lifespan:

1910, avg. 9 years1910, avg. 9 years 2010, avg. 55 years2010, avg. 55 years

Down SyndromeDown Syndrome

Majority (95%) - trisomy 21Majority (95%) - trisomy 21 47 instead of 46 chromosomes47 instead of 46 chromosomes Can occur before (faulty meiosis) or Can occur before (faulty meiosis) or

after fertilization (mosaicism)after fertilization (mosaicism) Small number - translocation Small number - translocation

(unrelated to maternal age)(unrelated to maternal age)

Prenatal DiagnosisPrenatal Diagnosis

Triple screen btw 15.5-20 wks Triple screen btw 15.5-20 wks gestationgestation

Quadruple screen 11-13 wksQuadruple screen 11-13 wks Advanced ultrasound: nuchal Advanced ultrasound: nuchal

translucencytranslucency AmniocentesisAmniocentesis

PostnatalPostnatal Begins with physical findingsBegins with physical findings

Phenotypic Features in Phenotypic Features in Down SyndromeDown Syndrome

Flattened nasal Flattened nasal bridgesbridges

Eye shapeEye shape Flat facial profileFlat facial profile Short limbsShort limbs Simian creases Simian creases Atlanto-axial Atlanto-axial

instabilityinstability Shallow acetabular Shallow acetabular

angleangle

Phenotypic Features in Phenotypic Features in Down Syndrome (Cont’d)Down Syndrome (Cont’d)

Cardiovascular:Cardiovascular: Ventricular septal Ventricular septal

defectdefect patent ductus patent ductus

arteriosusarteriosus Tetrology of FallotTetrology of Fallot

Vision/HearingVision/Hearing MyopiaMyopia NystagmusNystagmus StrabismusStrabismus Hearing lossHearing loss

Phenotypic Features in Phenotypic Features in Down Syndrome (Cont’d)Down Syndrome (Cont’d)

NeurologicalNeurological Overall reduced brain Overall reduced brain

weightweight May have smaller May have smaller

convolutions and other convolutions and other structural structural abnormalitiesabnormalities

Mild microcephalyMild microcephaly HypotoniaHypotonia Developmental DelayDevelopmental Delay Mental retardationMental retardation Early onset Alzheimer's Early onset Alzheimer's

diseasedisease

Phenotypic Features in Phenotypic Features in Down Syndrome (Cont’d)Down Syndrome (Cont’d)

OtherOther Retarded sexual Retarded sexual

developmentdevelopment Thyroid dysfunctionThyroid dysfunction Leukemia 20 times Leukemia 20 times

more likelymore likely

TRISOMY 18TRISOMY 18

Incidence 1:6,000 birthsIncidence 1:6,000 births males to females 1:3males to females 1:3

Mean maternal age advancedMean maternal age advanced AKA Edwards SyndromeAKA Edwards Syndrome 22ndnd most common trisomy most common trisomy 90% result in spontaneous abortion90% result in spontaneous abortion

CHARACTERISTICSCHARACTERISTICS

Pre and post natal growth retardationPre and post natal growth retardation Hypotonic at birthHypotonic at birth Hypertonic as they ageHypertonic as they age Congenital heart diseaseCongenital heart disease Dysmorphic featuresDysmorphic features

Trisomy 18Trisomy 18 90% Typically die in 90% Typically die in

infancyinfancy Survivors:Survivors:

developmental developmental delaydelay

mental retardationmental retardation

TRISOMY 13TRISOMY 13

IncidenceIncidence 1:5,000 births1:5,000 births 60% are female60% are female

Mean maternal age Mean maternal age increasedincreased

AKA Patau AKA Patau SyndromeSyndrome

Trisomy 13-Trisomy 13-CharacteristicsCharacteristics

Pre and post natal Pre and post natal growth deficiencygrowth deficiency

arrhinencephalyarrhinencephaly eye malformationseye malformations cleft lip and palatecleft lip and palate

Trisomy 13-Trisomy 13-CharacteristicsCharacteristics

Polydactyly or Polydactyly or syndactylysyndactyly

Congenital heart Congenital heart diseasedisease

Severe to profound Severe to profound cognitive cognitive impairmentimpairment

Trisomy 13-Trisomy 13-CharacteristicsCharacteristics

Death usually in infancy or by 2nd Death usually in infancy or by 2nd year of lifeyear of life

95% Spontaneous abortion95% Spontaneous abortion TREATMENTTREATMENT

SupportiveSupportive

Trisomy 13Trisomy 13