Mental Retardation

Mental RetardationMental Retardation

• First, need to know a basic First, need to know a basic understanding of “normal”understanding of “normal”

Distribution of IQDistribution of IQDistribution of IQDistribution of IQ

Distribution of IQDistribution of IQDistribution of IQDistribution of IQ

50 70 85 100 115 130 145

2.14% 13.59% 34.13% 34.13%13.59% 2.14%

0.13% 0.13%95.44%

68.26%

IQ score

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>150 Genius

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Many studies of genetic origins of low IQ, but not high IQ

>200"Super Genius"

+4 IGF2promotor PM

Mental RetardationMental Retardation

An individual is considered to have mentalAn individual is considered to have mental

retardation based on the following criteria:retardation based on the following criteria:• Sub-average IQ (less than 70-75)Sub-average IQ (less than 70-75)• Deficits in at least two areas of adaptive Deficits in at least two areas of adaptive

skills:skills:

communication, self-care, social skills, communication, self-care, social skills, academics, leisure, health, and safety.academics, leisure, health, and safety.

• Onset before the age of 18Onset before the age of 18

Mental RetardationMental Retardation

• Mental Retardation (MR) is defined by the Mental Retardation (MR) is defined by the American Association on Mental Retardation American Association on Mental Retardation (AAMR) by the following three criteria: (AAMR) by the following three criteria:

1.1. intellectual functioning level (IQ) is below 70-75intellectual functioning level (IQ) is below 70-752.2. significant limitations exist in two or more significant limitations exist in two or more

adaptive skill areas; and the condition manifests adaptive skill areas; and the condition manifests before the age of 18. before the age of 18.

3.3. Adaptive skill areas are those daily living skills Adaptive skill areas are those daily living skills needed to live, work, and play in the community. needed to live, work, and play in the community. The new definition includes ten adaptive skills: The new definition includes ten adaptive skills: communication, self-care, home living, social communication, self-care, home living, social skills, leisure, health and safety, self-direction, skills, leisure, health and safety, self-direction, functional academics, community use, and work.functional academics, community use, and work.

TerminologyTerminology

• OLD=retard, idiot, stupid, moronOLD=retard, idiot, stupid, moron• OLD=6 hour retardate OLD=6 hour retardate • What terminology is used today?What terminology is used today?

– Individual w/ MR, cognitive delays, Individual w/ MR, cognitive delays, developmental delaysdevelopmental delays

• MR is NOT a mental illness! MR is NOT a mental illness! – Ex. depression, schizophreniaEx. depression, schizophrenia

• Not a disease in itself, result of a Not a disease in itself, result of a diseasedisease

What is retardation?What is retardation?

DSM CriteriaDSM Criteria• IQ of 70 or below (Normal mean = 100, SD = 15, so 2 SD)IQ of 70 or below (Normal mean = 100, SD = 15, so 2 SD)• Deficits or impairments in present adaptive functioning in Deficits or impairments in present adaptive functioning in

at least two of the following:at least two of the following:CommunicationCommunication Self CareSelf CareHome LivingHome Living Social/ Interpersonal SkillsSocial/ Interpersonal SkillsCommunity ResourcesCommunity Resources Self-DirectionSelf-Direction

Functional Academic SkillsFunctional Academic Skills Work, Leisure, Health, and Work, Leisure, Health, and SafetySafety

• Onset before the age of 18 Onset before the age of 18 **arrested **arrested development**development**

What is retardation?What is retardation?

Differential Diagnosis:Differential Diagnosis:• Learning Disorders or Communication DisordersLearning Disorders or Communication Disorders• DementiaDementia• Pervasive developmental disordersPervasive developmental disorders

Presentation of Mental Presentation of Mental RetardationRetardation

The symptoms and signs of MR The symptoms and signs of MR include:include:

• Behavioral disturbances Behavioral disturbances • Language delayLanguage delay• Fine-motor and gross motor delay Fine-motor and gross motor delay • Neurological and physical Neurological and physical

abnormalities abnormalities • Children with MR also have visual Children with MR also have visual

and hearing impairmentsand hearing impairments

Presentation in Mental Presentation in Mental RetardationRetardation

Mental RetardationMental Retardation

• Diminished intellectual strengthDiminished intellectual strength• Less developed motor skillsLess developed motor skills• Better social and communication Better social and communication

skills in relation to overall skills in relation to overall developmental levelsdevelopmental levels

• Synonymous with global delaySynonymous with global delay

MRMR

• Mild Mild 70-55 IQ70-55 IQ• Moderate Moderate 55-40 55-40 • SevereSevere 40-2540-25• ProfoundProfound 25 & below25 & below

MILDMILD

• Cognitive standpoint:Cognitive standpoint:– 66thth grade level; can perform vocational-job grade level; can perform vocational-job

related skillsrelated skills

• AffectiveAffective– Acceptable social skills: able to communicate, Acceptable social skills: able to communicate,

acquire jobs, marryacquire jobs, marry

• PsychomotorPsychomotor– Delayed motor skills Delayed motor skills – Often obesity issues because of sedentary Often obesity issues because of sedentary

lifestyle lifestyle

Severity of Severity of RetardationRetardation

Mild Retardation:Mild Retardation: 85% of MR, 85% of MR, IQ 50-55 IQ 50-55 to 70to 70

develop social and communication skills in develop social and communication skills in preschool yearspreschool years

often not distinguishable from children often not distinguishable from children without retardation until later agewithout retardation until later age

only acquire academic skills up to only acquire academic skills up to approximately 6approximately 6thth grade level grade level

as adults- maintain unskilled jobs may need as adults- maintain unskilled jobs may need

social and financial assistancesocial and financial assistance

MODERATEMODERATE

• CognitiveCognitive– 22ndnd grade educational abilities grade educational abilities

• AffectiveAffective– Not as independent as mild; needs Not as independent as mild; needs

assistanceassistance

• PsychomotorPsychomotor– Obesity; greater motor delaysObesity; greater motor delays

Severity of Severity of RetardationRetardation

Moderate Retardation: Moderate Retardation: 10% of MR, 10% of MR, IQ 35-IQ 35-40 to 50-5540 to 50-55

acquire communication skills in later acquire communication skills in later childhood years childhood years

unlikely to progress beyond 2unlikely to progress beyond 2ndnd grade level grade level

difficulties recognizing social conventions difficulties recognizing social conventions and may interfere with and may interfere with

pure relationshipspure relationships

needs to be supervisedneeds to be supervised

SEVERE & PROFOUNDSEVERE & PROFOUND

• CognitiveCognitive– Learn some (not a lot) fundamental motor Learn some (not a lot) fundamental motor

skills, lack ability to attend to obvious stimuli, skills, lack ability to attend to obvious stimuli, very dependent upon others/lack self-help very dependent upon others/lack self-help skills, most cases non-verbalskills, most cases non-verbal

• AffectiveAffective– Lack play skills-don’t get the notionLack play skills-don’t get the notion

• PsychomotorPsychomotor– Retention of primitive reflexes; severe motor Retention of primitive reflexes; severe motor

delaysdelays

Severe Retardation: 3-4% of MR, IQ 20-25 to 35-40 little or no communicative speech function on an elementary level in both speech and self care physical abnormalities need constant supervision

Profound Retardation: 1-2% of MR, IQ below 20-25 neurological condition accounts for MR motor development, self care and communication skills may improve if appropriate instruction is provided but most can only perform simple tasks when heavily supervised

Severity of Retardation

MR and Mother’s AgeMR and Mother’s Age

16-20 = 1 in 2,00016-20 = 1 in 2,000

21-25 = 1 in 1,50021-25 = 1 in 1,500

26-30 = 1 in 1,00026-30 = 1 in 1,000

31-35 = 1 in 75031-35 = 1 in 750

36-44 = 1 in 3736-44 = 1 in 37

45-up = 1 in 1245-up = 1 in 12

• • Just because it isn’t heritable doesn’t mean it isn’t Just because it isn’t heritable doesn’t mean it isn’t genetic!genetic!

Etiology of Mental Etiology of Mental RetardationRetardation

Mental retardation can be caused by any Mental retardation can be caused by any condition which impairs the development of condition which impairs the development of the brain before birth, during birth or in the the brain before birth, during birth or in the childhood years. childhood years.

The major causes include:The major causes include:

• Genetic conditions: Down’s syndrome, Fragile Genetic conditions: Down’s syndrome, Fragile X-syndrome, and Tuberous sclerosisX-syndrome, and Tuberous sclerosis

• Problems during pregnancy: Fetal alcohol Problems during pregnancy: Fetal alcohol syndrome and smokingsyndrome and smoking

• Problems during birth: Pre-maturity and low Problems during birth: Pre-maturity and low birth weightbirth weight

• Problems after birth: Viruses such as chicken Problems after birth: Viruses such as chicken pox, measles, and meningitispox, measles, and meningitis

Prenatal (Before Birth) Prenatal (Before Birth) factors that may result in factors that may result in

MRMR• ChromosomalChromosomal• Prenatal influencesPrenatal influences• Maternal disease Maternal disease • Blood incompatibility-Rh factor Blood incompatibility-Rh factor • Maternal careMaternal care

Perinatal (At birth)Perinatal (At birth)

• Prematurity/post maturityPrematurity/post maturity• Low birth weightLow birth weight• Difficult labor & deliveryDifficult labor & delivery

CausesCauses

Hundreds of causes identified, although one-third of cases unknown

• Most involve a disruption of gene, or gene expression (i.e, “genomic”), but may or may not be heritable or familial

Most common:Fetal Alcohol SyndromeDown’s Syndrome (Trisomy 21)Fragile X Syndrome

Etiology of Mental Etiology of Mental RetardationRetardation

At least 1.5 million in the US have MRAt least 1.5 million in the US have MR• GeneticsGenetics• SESSES• Cultural deprivationCultural deprivation• DietDiet• Drugs (Alcohol)Drugs (Alcohol)• ParityParity• Mother’s AgeMother’s Age• Prenatal factorsPrenatal factors

Genetic forms: chromosomal Genetic forms: chromosomal abnormalitiesabnormalities

Chromosomal Abnormalities mostly spontaneous

DS Down’s Syndrome (1 in 1,000) Trisomy 21Most develop Alzheimer’s & lethal

WS William’s Syndrome (1 in 25,000) - Chr 7 LimKXXX Triple X Syndrome (1 in 1,000 F)XXY XXY Male Syndrome (1 in 750 M)AS Angelman Syndrome (1 in 25,000) from mother

15q11, UBE3A, GABR3 affectedPWS Prader-Willi Syndrome (1 in 15,000) from father

same locus as AS, but SNRPN gene affectedXYY XYY Syndrome (1 in 1,000 M)XO Turner’s syndrome (1 in 2,500 F)

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Genetic forms: single-gene Genetic forms: single-gene mutationsmutations

Single gene mutationsPKU Phenylketonuria (1 in 10,000) many mutations in

PAH gene for phenylalanine hydoxylase *diet*RS Rett Syndrome (1 in 10,000 F, lethal in M)

MECP2, methyl-CpG-binding protein-2FRX Fragile X Syndrome (1 in 1,250 M, 1 in 2500 F)

FMR1 expanding triplet repeatLNS Lesch-Nyhan Syndrome (1 in 20,000 M)

HPRT1, hypoxanthine phosphoribosyltransferaseDMD Duchenne Muscular Dystrophy (1 in 3,500 M)

huge DMD gene produces dystrophin doesn’t affect mice

NF1 Neurofibromatosis (1 in 3,000 births)huge NF1 gene

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Leading Causes of MRLeading Causes of MR

1. Fetal Alcohol Syndrome-leading cause1. Fetal Alcohol Syndrome-leading cause– 5 in 10,000 births5 in 10,000 births– Cause by drinking while pregnantCause by drinking while pregnant– ONLY cause of MR that is preventableONLY cause of MR that is preventable

• AttributesAttributes– Small brain (microcephaly)Small brain (microcephaly)– Growth deficiencies Growth deficiencies – Behavior problemsBehavior problems– Heart murmursHeart murmurs

• All these may impact how they perform All these may impact how they perform physical activityphysical activity

Leading Causes of MRLeading Causes of MR

• Fragile X SyndromeFragile X Syndrome– Chromosomal anomaly-inheritedChromosomal anomaly-inherited– Males more than femalesMales more than females

• Approximately 95% of those with full Approximately 95% of those with full mutation have MRmutation have MR

• Approx. 50% of females affected have MRApprox. 50% of females affected have MR

– Most commonly occurring inherited Most commonly occurring inherited cause of MRcause of MR

Fragile X SyndromeFragile X Syndrome

• Single gene mutation located on the X Single gene mutation located on the X chromosome.chromosome.

• Since both males (XY) and females (XX) each have Since both males (XY) and females (XX) each have at least one X chromosome, both can be carriers or at least one X chromosome, both can be carriers or have the syndrome.have the syndrome.

• If a father is a carrier, he can only pass the gene If a father is a carrier, he can only pass the gene defect to his daughters, since he transmits a Y defect to his daughters, since he transmits a Y chromosome to his sons. chromosome to his sons.

• If a mother is the carrier, she can pass the gene If a mother is the carrier, she can pass the gene defect to either sons or daughters, since she defect to either sons or daughters, since she contributes an X chromosome to each. contributes an X chromosome to each. – Children of carrier mothers have a 50% chance of Children of carrier mothers have a 50% chance of

inheriting the gene, since the mother has two Xs to give inheriting the gene, since the mother has two Xs to give and only one is affected. and only one is affected.

Fragile X SyndromeFragile X Syndrome

• AttributesAttributes– Males (more severely affected than females) Males (more severely affected than females)

problems with social skills, developmental problems with social skills, developmental delays, cognitive and communication skills are delays, cognitive and communication skills are most affected. Lack of eye contact is frequently most affected. Lack of eye contact is frequently observed. observed.

– Females (more mild impairments)Females (more mild impairments)• Females have 2 Xs, but in each cell only one becomes Females have 2 Xs, but in each cell only one becomes

activated (random)activated (random)• One-third with full mutation will have normal One-third with full mutation will have normal

development, one-third will exhibit learning disabilities development, one-third will exhibit learning disabilities and one-third will have mental retardation. and one-third will have mental retardation.

Down SyndromeDown Syndrome

• John Langdon Down- clinically John Langdon Down- clinically identified the condition in 1866. identified the condition in 1866.

• Caused by extra genes in the 21st Caused by extra genes in the 21st chromosome. chromosome.

Down SyndromeDown Syndrome• The extra genes cause certain The extra genes cause certain

characteristics that we know as Down characteristics that we know as Down syndrome. Individuals with Down syndrome. Individuals with Down Syndrome also have all the other genes Syndrome also have all the other genes given to them by their parents. As a result, given to them by their parents. As a result, they have a combination of features they have a combination of features typical of Down Syndrome on top of the typical of Down Syndrome on top of the individual features from their parents. individual features from their parents.

• Some of the physical traits that are Some of the physical traits that are common but not always present are common but not always present are almond eyes, flattened bridge of the nose, almond eyes, flattened bridge of the nose, a single palmar crease and hyperflexibility. a single palmar crease and hyperflexibility.

Down SyndromeDown Syndrome

• A recent estimate in the United States puts A recent estimate in the United States puts the incidence at about 1 in 1,000. the incidence at about 1 in 1,000.

• There is no association between Down There is no association between Down Syndrome and any given culture, ethnic Syndrome and any given culture, ethnic group, socioeconomic status or geographic group, socioeconomic status or geographic region. region.

• In the usual circumstance, the chances In the usual circumstance, the chances depend upon the age of the mother. depend upon the age of the mother. – The odds of having a child with Down Syndrome at The odds of having a child with Down Syndrome at

age 35 are approximately 1 in 350.age 35 are approximately 1 in 350.– Under age 25, the odds are about 1 in 1400 Under age 25, the odds are about 1 in 1400 – At age 40 the odds are about 1 in 100. At age 40 the odds are about 1 in 100.

Trisomy 21Trisomy 21

• About 95% of people with Down About 95% of people with Down Syndrome have Trisomy 21Syndrome have Trisomy 21

• In Trisomy 21, the twenty-first In Trisomy 21, the twenty-first chromosome pair does not split and chromosome pair does not split and a double-dose goes to the egg (or a double-dose goes to the egg (or sperm). It is estimated that 95-97% sperm). It is estimated that 95-97% of the extra chromosome is of of the extra chromosome is of maternal origin. maternal origin.

TranslocationTranslocation

• Occurs in about 3-4% of people with Occurs in about 3-4% of people with Down Syndrome. Down Syndrome.

• An extra part of the twenty-first An extra part of the twenty-first chromosome gets stuck onto another chromosome gets stuck onto another chromosome. In about half of these chromosome. In about half of these situations, one parent carries the situations, one parent carries the extra twenty-first chromosome extra twenty-first chromosome material in a "balanced", or hidden, material in a "balanced", or hidden, form. form.

MosaicsmMosaicsm

• The person with Down Syndrome The person with Down Syndrome has an extra twenty-first has an extra twenty-first chromosome in only some of the chromosome in only some of the cells but not all of them. The other cells but not all of them. The other cells have the usual pair of twenty-cells have the usual pair of twenty-first chromosomes. first chromosomes.

• One to 2 percent of people with One to 2 percent of people with Down Syndrome have this type.Down Syndrome have this type.

Down SyndromeDown Syndrome

• Motor DevelopmentMotor Development– 2-3 years until they walk (unless early intervention)2-3 years until they walk (unless early intervention)

• BalanceBalance– 1-2 years delayed/awkward gait1-2 years delayed/awkward gait

• Often have vision problems=glassesOften have vision problems=glasses• Congenital heart disease-can’t take heart rate too Congenital heart disease-can’t take heart rate too

highhigh• Obesity as they get olderObesity as they get older

– Lack of exerciseLack of exercise– Don’t know when to stop eating/don’t know the feeling of Don’t know when to stop eating/don’t know the feeling of

fullnessfullness

• Upper respiratory infections-have colds A LOT Upper respiratory infections-have colds A LOT (more often than not)(more often than not)

Atlantoaxial InstabilityAtlantoaxial Instability

• Too much mobility between C1 & C2 Too much mobility between C1 & C2 vertebratevertebrate

• Possible serious injury if neck is Possible serious injury if neck is forcibly flexedforcibly flexed

• REMEMBER THE NECK THING!REMEMBER THE NECK THING!• Physician does x-rays from side and Physician does x-rays from side and

front; done at ages 3, 12 & 18 front; done at ages 3, 12 & 18 (development stages) (development stages) – While neck is neutral, flexed and While neck is neutral, flexed and

extendedextended

Atlantoaxial InstabilityAtlantoaxial Instability

• Restricted activitiesRestricted activities– GymnasticsGymnastics– DivingDiving– High jumpHigh jump– SoccerSoccer

• Exercises involving pressure placed Exercises involving pressure placed on neck muscleson neck muscles

• Be safe rather than sorry!Be safe rather than sorry!

Treatments:Treatments:

Mental RetardationMental Retardation

• Medical treatment: special educators, Medical treatment: special educators, language therapists, behavioral language therapists, behavioral therapists, occupational therapiststherapists, occupational therapists

• No specific drug to treat cognitive No specific drug to treat cognitive deficiency, but can be prescribed for deficiency, but can be prescribed for specific comorbid psychiatric disease or specific comorbid psychiatric disease or behavioral disturbances behavioral disturbances

Treatments:Treatments:

Mental RetardationMental Retardation

• Diet: Nutritional supplements not Diet: Nutritional supplements not proven to treatproven to treat

TEACHING TIPSTEACHING TIPS

• Provide frequent feedback to the individual.Provide frequent feedback to the individual.• Provide short and clear instructions.Provide short and clear instructions.• Repeat directions.Repeat directions.• Have the individual demonstrate the task for clear Have the individual demonstrate the task for clear

understanding.understanding.• Keep the learning environment consistent with Keep the learning environment consistent with

little change.little change.• Eliminate distractions (visual and auditory).Eliminate distractions (visual and auditory).• Demonstrate tasks for visual understanding.Demonstrate tasks for visual understanding.• Use peers as partners for the individual with MR.Use peers as partners for the individual with MR.• Slow down the speed of the activity especially if it Slow down the speed of the activity especially if it

is concerning a noncompetitive activityis concerning a noncompetitive activity

Teaching PE to MRTeaching PE to MR

• Tendency for obesity=sedentary lifestyleTendency for obesity=sedentary lifestyle• Use weight machines instead of free Use weight machines instead of free

weights=safety! Stabilityweights=safety! Stability• Jogging/walking-needs supervision/know Jogging/walking-needs supervision/know

target heart rate/max heart ratetarget heart rate/max heart rate• Don’t be afraid to modify!Don’t be afraid to modify!• Adapt activities to eliminate gravityAdapt activities to eliminate gravity• Monitor progress Monitor progress

Teaching Motor SkillsTeaching Motor Skills

• Use peer involvement! Use peer involvement! • Start simple and move to complexStart simple and move to complex• Use motivating targetsUse motivating targets• Use music! Use music! • Tell stories Tell stories

Teaching Strategies for Teaching Strategies for students with more severe students with more severe

levels of MRlevels of MR• Use visual stimulation: bright colors, Use visual stimulation: bright colors,

flashlights, mirrors, etcflashlights, mirrors, etc• Use tactile stimulation Use tactile stimulation • Grasping/releasingGrasping/releasing

ConclusionsConclusions

Multiple causes of retardation suggest that intelligence is complex

>> easy to disrupt genetically or during development

With few exceptions most forms of mental retardation involve disruption of genes, but may not be familial or heritable because mutation arises spontaneously

Present studies focus on copying mutations in mice and then trying to treat deficits in mice.