What is Mental Retardation?

The words “Mental Retardation” tends to not be a politically correct term to use these days.  However, According to the current Diagnostic and Statistical Manuel of Mental Disorders-IV-TR published by the American Psychiatric Association, this is the correct medical terminology. 

 mental retardation awarenessCredit: www.foothillechoes.com

How mental retardation is diagnosed is controversial and there have been many court decisions that provide information about how IQ test can be used.  The research and the standardization of scores have provided great help to those who may use of the test and are charged with making the diagnoses. 


People with the diagnosis of mental retardation, must meet certain criteria by using information on psychological test.  There must be an Intelligent Quotient (IQ) of 70 or below on standardized Intelligent Quotient test.  Some of the most popular IQ test used in the United States is as follows (this list is by no means exhaustive of the IQ test available):

  • Wechsler Preschool and Primary Scale of Intelligence (WPPSI).  This test is used for children ages 2:6 to 7:3. 
  • Wechsler Intelligence Scale for Children (WISC).  This test is used for children and adolescent between the ages of 6 and 16.
  • Wechsler Adult Intelligence Scale (WAIS).  This test is used for those people between the ages of 16 and 90.
  • Kaufman Adolescent and Adult Intelligence Test (KAIT).  This test is used for people over the age of 11.
  • Reynolds Intellectual Assessment Scale (RIAS). This test is used for people from age 3 to 94.
  • Stanford-Binet Intelligence Scale-5th Edition (SB5). This test can be used for anyone over the age of 2. 
  • Woodcock Johnson Test of Cognitive Skills. This test can be used for anyone over the age of 2.


The Wechsler tests are the most widely used by far and I will attempt to explain how scores are derived only on these tests for information purposes only.  The standard score of 100 means that 50% of the people, when test are expected to perform better and 50% will perform worse.  The Wechsler tests have a standard deviation of 15.  Those scoring at one standard deviation below the means would be a score of less than 85.  68% of the people taking this test will score between 85-115.  This is how the test is set up.  Two standard deviations would be a score of 70 or below. Only about 2.5% of the people will have a score lower than this. The score of 70 or below is a criterion for mental retardation. 

bell curveCredit: www.wilderdom.com


In addition to the criteria of an IQ 70 or below the person must also have significant delays in adaptive functioning.  The dictionary defines adaptive functioning as  “he relative ability of a person to effectively interact with society on all levels and care for one's self; affected by one's willingness to practice skills and pursue opportunities for improvement on all levels. Often used to describe levels of mental retardation.” (http://medical-dictionary.thefreedictionary.com/adaptive+functioning). 


As with the IQ test there are many instruments for testing adaptive functioning.  The most widely known are as follows: 

  • Vineland Adaptive Behavior Scales.  There are two versions of this test.  One for teachers and one for parent/caregivers.  The teacher version is only for those 3 years to 12 years old.  The parent/caregiver version is for all ages. 
  •  Scales of Independent Behavior (SIB-R). This instrument can be used for those 3 months old to 80 years young.
  • AAMR Adaptive Behavior Scale 2nd edition (AAMR ABS).  There are two versions of this instrument.  One for use in the classroom and one for use in the community.   


There are 4 degrees of severity when discussing mental retardation.  They degrees are based on the IQ scores when compared to statistics when the test was “normed”.  That means when it was given to a lot of people to get more and improved data.  The degrees or severity of mental retardation is as follows:

  • Mild Mental Retardation.  This is the category for people whose IQ are between 55-70.  That is between 2-3 standard deviations from the norm.
  • Moderate Mental Retardation.  This is the category for people who have an IQ between 40-55.  This is between 3-4 standard deviations from the norm.
  • Severe Mental Retardation.  This is the category for people who have an IQ between 25-40.  This is between 4-5 standard deviations from the norm.
  • Profound Mental Retardation.  This is the category for people with an IQ below 25.  This is more than 5 standard deviation from the norm. 


One last criteria for the diagnosis of Mental Retardation.  The onset of the problems must occur before the age of 18.  There are many things that could cause a loss of cognitive functioning in adulthood, but these are usually classified in other categories and not referred to as mental retardation. 


Symptoms of Mental Retardation

Mental RetardationCredit: kidshealth.org

This is a hard section to write about when referring to mental retardation.  Those with mild mental retardation can still functioning pretty well in society and can even live independently.  They can do most of what other people without the diagnosis can do in regards to daily activities, but may need some help or need someone to explain some more advanced things to them.  Their abstract reasoning may be compromised. 


Those with profound mental retardation have very little functioning abilities and will usually need to be place in residential or care centers for every basic need. 


Those between may have varying degrees of problems and I would not want to commit to say they could not live independently, but I would not want to say they could. 

Generally speaking and based on adaptive functioning people with a mental retardation diagnosis will have difficulty with daily activities of life, such as dressing themselves, preparing meals and maintaining money.


They may also have problems with social skills.  That is getting along with others, participating in family and group activities and understanding group rules and norms.


Communication skills may be compromised and they may not understand or be able to express their needs, wants, and desires. 


Treatment of Mental Retardation

As there is no cure for mental retardation, the most likely form of treatment will be educational.  Persons with mental retardation can still learn, but as the name implies, the learning will be retarded, or slow.  They can be taught to live independently even if this is not the goal.  They can be taught to take care of themselves and provide a services to others when needed.  I know of one organization in my area, which provides a Sheltered Workshop, where people with lower functioning can be taught a trade and provide services. 

 cause of mental retardationCredit: www.medivisuals.com

Other resources about Mental Retardation

There are many great organizations out there that help with person with intellectual disabilities.


One such organization is the American Association on Intellectual and Developmental Disabilities.  They produce two major professional journals on this topic and work with communities, schools, and organizations to help promote their cause. 


Project IDEAL is an organization that provides information and support to teacher and helps them learn to work with people with disabilities.  They are doing some great work. 

Mental Retardation: An Introduction to Intellectual Disability (7th Edition)
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Understanding Mental Retardation (Understanding Health and Sickness Series)
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