Mental Retardation/Intellectual Disability: Definition and its causes

Mental Retardation/Intellect

ual Disability: Definition and its

causesPresented by:

Mirasol S. MadridIII-9 BS Psychology

What is Mental

Retardation/Intellectual disability?

Mental Retardation

“Mental retardation refers to substantial limitations in present functioning. It is

characterized by significantly sub-average intellectual functioning, existing concurrently with related limitations in two or more of the

following adaptive skills areas: communication, self-care, home living, social skills, community

use, self-direction, health and safety, functional academics, leisure and work. Mental

retardation manifests before age 18.” (Heward, 2003)

Mental Retardation

• Substantial limitations in present functioning means that the person has difficulty in performing everyday activities related to taking care of one’s self, ordinary tasks at home and work related to other adaptive skills areas. Academic work is also included, if the person goes to school.

Mental Retardation

• Significantly sub-average intellectual functioning means that the person has significantly below average intelligence. The person has difficulty to learn, solve problems, accumulate knowledge and adapt to new situations. However, sub-average intellectual functioning can change.

Mental Retardation

• Limitations in the adaptive skills or behavior means that the person with mental retardation fail to meet the standards of personal independence and social responsibility expected of their chronological age and cultural group. Adaptive skills are assessed by means of standardized adaptive behavior scales.

Mental Retardation

• Related limitations in the adaptive skills areas means that the person has difficulty in performing the following tasks: communication, self-care, home living, community use, social skills, self-direction, health and safety, functional academics, leisure and work.

Mental Retardation

• Mental Retardation is a developmental disability.

• NOTE: It is important that the person must meet all three of the above criteria. Thus, an IQ score below 70 or 75 is not sufficient to classify a person as with mental retardation.

INTELLECTUAL DISABILITY

Mentally defectiveMentally deficient

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Moron

Imbecile

Idiot

Idiot

Feebleminded

ImbecileMentally defective

Men

tally

defi

cien

t Idiot

ImbecileRetard

Moron

What are the classifications

of Mental Retardation?

Classification of Mental Retardation

In the previous American Association on Mental Retardation classification system, there are four levels that are still widely used today (based on IQ score):

Classification IQ Score

MILD MR 55-70

MODERATE MR 40-54SEVERE MR 25-39

PROFOUND MR Below 25


In the previous American Association on Mental Retardation classification system, there are four levels that are still widely used today (based on IQ score):


MILD MR- Educable (6th grade)

- May live independently, with

community and social support

55-70



MODERATE MR- Trainable (work and

self-care task)- Acquires

communication skills- May live and function

successfully within the community

40-54



SEVERE MR- They may master very

basic self-care skills and some

communication skills

25-39

PROFOUND MR- May develop basic

self-care skills and communication skills

- Needs high supervision

Below 25


However, the AAMR has introduced a new system of classification that is based on the amount of support that the person needs in order to function to the highest possible level The four categories of mental retardation according to the intensity of needed supports are: (Wehmeyer, 2002)


Classification Support Needed

Intermittent Support

are on “as needed” basis, that is, the person needs help only at certain periods of time and not all the time. Support will most likely be required during periods of transition. (e.g. moving from school to work.)



Limited Supports

are required consistently, though not on a daily basis. The support needed is of non-intensive nature.



Extensive Supports

are needed on a regular basis; daily supports are required in some environments, for example, daily home living tasks.



Pervasive Supports

are daily extensive supports, perhaps of a life-sustaining nature required in multiple environments.

What are the causes of MR?

Causes of Mental Retardation

There are more than 250 identified causes of mental retardation. The AAMR classifies the causes or etiological factors based on: Time of onset

A. Prenatal or Biological (before birth)

B. Perinatal (during birth)C. Postnatal and Environmental (after

birth)


A.Prenatal or Biological (before birth)Prenatal causes are those that

originate during conception or pregnancy until before birth are chromosomal disorders such as trisomy 21 or Down Syndrome, Klinefelter syndrome, Fragile X syndrome, Prader-Willi syndrome, Phenylketonuria, and William Syndrome.


Chromosomal Disorder

Cause Characteristics

• Down Syndrome

Was named after Dr. Langdon Down

the best known and well researched biological condition associated with MR

affects 1 in 1,000 live births

Chromosomal abnormality

Trisomy 21 – the 21st set is a triplet rather than a pair which often results in the moderate level of MR

Correlated with the age of the mother

can also be a result of a nondisjunction of the father’s chromosome 21

Flat, broad face Small ears and

nose Upward slanting

eyes Small mouth with

short roof Protruding tongue Hypertonia or

floppy muscles Shorter life span Sexually

underdeveloped sterile




• Klinefelter Syndrome

More associated with learning disability

Males are commonly affected

Extra X chromosome resulting to: XXY

XXY is usually caused by what is called nondisjunction. Nondisjunction happens when a pair of sex chromosomes fails to separate during egg (or sperm) formation.

Male sex organs are underdeveloped: unusually small testicles

Sterile Has female

secondary sex characteristics: breast enlargement and other feminine characteristics

Less-muscular bodies

Wider hips, low growth of facial hair




• Fragile X Syndrome

Most common MR next to DS

Occurs in both gender but males are mostly affected

Majority of males experience mild to moderate MR (childhood) and moderate to severe MR (adulthood)

A triplet or repeat mutation on the X chromosome interferes with the production of FMR-1 protein which is essential for normal brain functioning

Most people have 29 repeats at this end of their X chromosome but people with FX have over 700 repeats

Males: Intellectual Disability, large ears, long face, soft skin, large testicles, flat feet, double-jointed fingers. They may also have: social anxiety, poor-eye contact, tactile defensiveness, ritualistic forms of greeting

Females: milder presentation of the characteristics




• William Syndrome

Results in learning problems, attention deficit disorder, anxiety, phobias but they have outgoing personality

Occurs equally in both male and female and in every culture

WS is caused by the deletion of a portion of chromosome 7

The deleted area includes more than 25 genes so amount of genetic material deleted may vary

Deletion of chromosomes are due to random events that occur in eggs or sperm from their parents

Elfin or dwarf-like features (e.g. small eye openings, broad forehead, short nose with a broad tip, full cheeks, wide mouth with full lips, and dental problems)

They lack reserve toward strangers

Weak in visual-spatial skills

Often hyperactive




• Prader-Willi syndrome

Syndrome disorder Associated with

mild retardation and learning disability

PWS is caused by the deletion of a portion of chromosome 15

May also occur if the person has a copy of chromosome 15 from the maternal side instead of each of the parent

Infants: floppy-muscles, feeding difficulties, delayed development

Childhood: insatiable appetite that may result to chronic overeating (hyperphagia) or obesity

Beh. Problems are common: impulsitivity, aggressiveness, OCD and tantrums




Translocation, or mutation that inactivates that paternal chromosome 15

Physical features: narrow forehead, almond-shaped eyes, triangular mouth, short stature, small hands and feet. Some may have unusually fair skin and light colored hair

Male and female affected may have underdeveloped genitals. Most are also infertile




• Phenylketonuria (PKU)

Inborn errors of metabolism

Genetically inherited

A child is born without an important enzyme to break down an amino acid called Phenylalanine (Phe) found in dairy and protein rich foods

PKU is inherited if both the mother and the father is a carrier of the defective gene

Because of the failure to breakdown the Phe, this causes brain damage, that results in aggressiveness, hyperactivity, and severe mental retardation

Symptoms may include: beh. And social problems, seizures or jerking movements, hyperactivity, skin rashes, microcephaly, musty odor in the child’s breath, skin or urine due to too much Phe.

They have fair skin and blue eyes

CRANIAL Malformation

• Occurs in developmental disorders of brain formation– Anencephaly the major portions of

the brain are absent. This is a major neural tube defect, that is, it occurs in the brain or in the spinal cord.

–Microcephaly the skull is small and conical, the spine is curved and typically leads to stooped portion and severe mental retardation

CRANIAL Malformation

–Hydrocephaly blockage of cerebrospinal fluid in the cranial cavity causes an enlarged head and undue pressure on the brain.

ANENCEPHALY

MICROCEPHALY

HYDROCEPHALY

Mental Retardation may also occur due to environmental influences such as:

–Maternal Malnutrition– Irradiation during pregnancy– Juvenile diabetes mellitus – Fetal alcohol syndrome or FAS

FAS is one of the leading causes of MR. This is due to the mother’s excessive alcohol use during pregnancy

Fetal Alcohol Effect or FAE happens due to the mother’s prenatal alcohol exposure. FAE is a condition associated with hyperactivity and learning problems. It is characterized by cognitive impairment, sleep disturbances, motor dysfunctions, hyperirritability, aggression and conduct problems. FAS’ incidence is higher than DS and cerebral palsy

FAS/FAE


B. Perinatal (during birth) mental retardation may occur by:

- Intrauterine Disorders such as maternal anemia, premature delivery, abnormal presentation, umbilical cord accidents and multiple gestations in the case of twins, triplets, quadruplets and other types of multiple births. Birth trauma may result from anoxia or cutting off of oxygen supply to the brain.


B. Perinatal (during birth) mental retardation may occur by:

-Neonatal Disorders such as intracranial hemorrhage, neonatal seizures, respiratory disorders, meningitis, encephalitis, head trauma at birth.


C. Postnatal and Environmental (after birth) mental retardation may occur due to:

- head injuries cerebral concussion, contusion or laceration

- infections encephalitis, meningitis, malaria, German measles, rubella;

- demyelinating disorders post infectious disorders, post immunization disorders



- Degenerative disorders Rett syndrome, Huntington disease, Parkinson’s disease;

- Seizure disorders – epilepsy, toxic-metabolic disorders such as Reye’s syndrome, lead or mercury poisoning

- Malnutrition – especially lack of proteins and calories;



-Environmental deprivation such as psychosocial disadvantage, child abuse and neglect, chronic social/sensory deprivation

Though accidents, particularly vehicular accidents, are the leading causes of childhood head injuries, the shaken baby syndrome, which is a type of child abuse when a crying infant is violently shaken by a frustrated caregiver, can result to head injury. This often results in internal bleeding and brain damage, or in some cases, even death.

Cultural-familial retardation refers to the existence of lowered intelligence of unknown origin associated with a history of mental retardation in one or more family members.

Diseases of the mother during pregnancy may also result in retardation. Infections caused by sexually transmitted diseases such as syphilis, gonorrhea, AIDS, toxoplasmosis (blood poisoning) and rubella can have negative effects on the developing fetus. Maternal rubella is most likely to cause retardation, blindness, or deafness when the disease occurs during the first trimester of pregnancy.

Education

Mental Retardation/Intellectual Disability: Definition and its causes