1. Intellectual Disabilities
An Overview of
Intellectual Disabilities

2. Learning Objectives Participants will be able to:
Define levels of severity of mental retardation.
Identify the primary comorbid Axis I disorders.
Describe risk factors for mental retardation.
Identify the most common causes of mental retardation.

3. Intellectual Disability once called Mental Retardation is characterized by below average intelligence and a lack of skills essential for day to day living. There are varying degrees of intellectual disability: from mild to profound. Definition: There are two areas of limitations: Intellectual Functioning: known as IQ and refers to the individual’s ability to learn, make decisions and solve problems. Adaptive Behaviors: these are skills necessary for day to day life such as communicating effectively, interacting with others and caring for oneself.

4. In America – the average IQ is 100 with the majority of people scoring between 85 – 115. A person is considered intellectually disabled if their IQ is less than 70 or 75. The individual is diagnosed before the age of 18. To measure adaptive behavior, a clinician will observe and compare the child’s skills to children of the same age. We observe their ability to feed or dress themselves, communicate with others and understand what others are communicating to them. We also administer standardized tests to assess adaptive skills. A child must have deficits in IQ and adaptive behavior to be diagnosed with intellectual disability. Intellectual Disabilities affect about 1% of the population. About 85% have mild intellectual disability.

5. What are the signs of intellectual disability in children?
Some of the signs appear during infancy or may not be observed until the child reaches school age.
It depends on the severity of the disability.
The common signs are:
Lack or slow development of motor skills; language skills, self-help skills; crawling or walking late
Lack of curiosity; difficulty understanding social rules
Slow to master potty training, dressing, feeding oneself
Inability to connect actions with consequences
Behavior problems such as explosive tantrums
Difficulty remembering; difficulty with problem solving or logical thinking
In children with severe or profound intellectual disability there may be other related health problems such as:
Seizures, mood disorders, anxiety, autism, motor skill impairment, vision or hearing problems.

6. Definition Deficits in IQ and adaptive functioning IQ of 70 or below
Measured by standard scales
Wechsler, Stanford-Binet, Kaufman
Impairments in Adaptive Functioning
Effective coping with common life demands
Ability to meet standards of independence
Vineland, AAMR Adaptive Behavior Scale

7. Degrees of Severity Mild Mental Retardation
IQ: to approximately 70
Moderate Mental Retardation
IQ: to 50-55
Severe Mental Retardation
IQ: to 35-40
Profound Mental Retardation
IQ: Less than 20-25

8. Mild Mental Retardation
Previously referred to as “educable”
Largest segment of those with MR (85%)
Typically develop social/communication skills during preschool years, minimal impairment in sensorimotor areas.
By late teens acquire skills up to approximately the 6th grade level

9. Moderate Mental Retardation
Previously referred to as “trainable”
About 10% of those with MR
Most acquire communication skills during early childhood years
Generally benefit from social/vocational training and with moderate supervision can attend to personal care
Difficulties recognizing social conventions which interferes with peer relations in adolescence
Unlikely to progress beyond the 2nd grade academically
Often adapt well to life in the community in supervised settings (performing unskilled or semiskilled work)

10. Severe Mental Retardation
3 – 4% of those with MR
Acquire little or no communicative speech in childhood; may learn to talk by school age and be trained in elementary self-care skills
Able to perform simple tasks as adults in closely supervised settings
Most adapt well to life in the community, living in group homes or with families

11. Profound Mental Retardation
1 – 2% of those with MR
Most have an identifiable neurological condition that accounts for their MR
Considerable impairments in sensorimotor functioning; ability to plan and organize motor functions; sequencing movements to complete a task
Optimal development may occur in a highly structured environment with constant aid

12. Prevalence 1% (1 – 3% in developed countries)
The prevalence of MR due to biological factors is similar among children of all SES; however, certain etiological factors are linked to lower SES (e.g., lead poisoning & premature birth)
In cases without a specifically identified biological cause, the MR is usually milder; and individuals from lower SES are over-represented

13. Psychiatric Features No specific personality type
Lack of communication skills may predispose to disruptive/aggressive behaviors
Prevalence of comorbid Axis I disorders is 3-4 times that of the general population
Patients with MR and comorbid Axis I disorders respond to medications much the same as those without MR

14. Most Commonly Associated Axis I Disorders
ADHD
Mood Disorders
Pervasive Developmental Disorders
Stereotypic Movement Disorders
Mental Disorders due to a GMC

15. Causes of Intellectual Disability
Intellectual Disability can be caused by any condition that impairs development of the brain before birth, during birth or in the childhood years.
Several hundred causes are known.
In about one third of the cases, the causes remain unknown.
The three main causes of intellectual disability are:
Down Syndrome, Fetal Alcohol Syndrome, Fragile X Syndrome.
Genetic Conditions: these result from abnormalities of genes inherited from parents or from other disorders of genes cause during pregnancy by infections and other factors.
Other genetic diseases associated with intellectual disability include PKU (phenylketonuria) a single gene disorder; due to a missing or defective enzyme which causes intellectual disability.
Down Syndrome: a chromosomal disorder, caused by too many or too few chromosomes or by a change in structure of a chromosome.
Fragile X Syndrome: a single gene disorder located on the x chromosome.

16. Complications During Pregnancy: problems with fetal brain development include alcohol or substance use, malnutrition, environmental toxins, infections. Problems During Childbirth: the baby may be deprived of oxygen or born extremely premature. Problems After Birth: whooping cough, chicken pox, measles, meningitis, encephalitis can damage the brain; lead, mercury and other environmental toxins can cause irreparable damage to the brain and nervous system. Poverty and Cultural Deprivation: children growing up in poverty are at higher risk for malnutrition, childhood diseases, exposure to environmental health hazards and these kids often receive inadequate health care.

17. Sometimes intellectual disability is also referred to as developmental disability which is a broader term that includes: ASD: Autism Spectrum Disorders Epilepsy Cerebral palsy Fetal Alcohol Syndrome Major differences are in the age of onset, severity of limitations and the individual with a developmental disability may or may not have a low IQ.

18. Can Intellectual Disability be Prevented?
Certain causes are preventable.
The most common cause is fetal alcohol syndrome.
Pregnant women should not consume alcohol.
If there is a history of genetic disorders, genetic testing is recommended before conception.
An ultrasound can be done and amniocentesis during pregnancy to determine if there problems associated with intellectual disability.

19. Predisposing Factors (3)
Environmental Influences (15-20% of cases)
Deprivation of nurturance, social/linguistic and other stimulation
Mental Disorders
Autism & other PDDs
Pregnancy & Perinatal Problems (10% of cases)
Fetal malnutrition, prematurity, hypoxia, viral and other infections, trauma
General Medical Conditions Acquired in Infancy or Childhood (5% of cases)
Infections, trauma, poisoning (e.g., lead)

20. Disability Low birth weight is the strongest predictor of disability
Male children and those born to black women and older women in the USA are at increased risk for ID
Lower level of maternal education is also independently associated with degree of disability

21. Etiology At least 500 causes now known
Over 150 MR syndromes have been related to the X-chromosome
Most common cause of MR:
Down’s Syndrome (most common genetic cause)
Fragile X Syndrome (accounts for 40% of all X-linked syndromes; most common inherited cause)
Fetal EtOH Syndrome (most common attributable cause)
together these 3 account for 30% of all identified cases of MR

22. Behavior & Psychiatric Illness in Downs
Recent population based survey of social and healthcare records found:
Females had better cognitive abilities and speech production compared with males
Males had more behavioral troubles
ADHD symptoms were often seen in childhood across gender
Depression was diagnosed more often in adults with mild/moderate intellectual impairment
Autistic behavior was most common in those with profound intellectual disability
Elderly often showed a decline in adaptive behavior consistent with Alzheimer’s
Maatta et al, 2006