What Is Borderline Intellectual Functioning?

How important is IQ to diagnosis?

EXAMINATION PAPERS ON DESKS
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Mental Retardation vs. Intellectual Development Disorder

In the Diagnostic and Statistical Manual of Mental Disorders version 4 (DSM-IV), there was a diagnostic category called "mental retardation." In 2013, when the new DSM-5 came out, mental retardation had disappeared; in its place was a new disorder called "intellectual development disorder."  

People with "mental retardation" were diagnosed using DSM IV, and the diagnosis was made largely through standardized IQ tests.

If IQ scores came out below 70, the individual was considered to have an intellectual disability.  

People with "intellectual development disorder" are diagnosed using DSM-5, and while IQ scores still play an important role, others issues are considered. According to the Intellectual Disability Fact Sheet from the American Psychiatric Association (which publishes the DSM):

In DSM-5, intellectual disability is considered to be approximately two standard deviations or more below the population, which equals an IQ score of about 70 or below. The assessment of intelligence across three domains (conceptual, social, and practical) will ensure that clinicians base their diagnosis on the impact of the deficit in general mental abilities on functioning needed for everyday life. This is especially important in the development of a treatment plan. The updated criteria will help clinicians develop a fuller, more accurate picture of patients, a critical step in providing them with effective treatment and services. 

Borderline Intellectual Functioning

Borderline intellectual functioning refers to estimated intelligence quotient scores within the 70 to 75 range on an intelligence test with an average of 100 and standard deviation of 15. The range is called borderline because it is on the borderline of the criteria for the diagnosis of intellectual disabilities (historically referred to as mental retardation) in the Diagnostic and Statistical Manual of Mental Disorders (DSM).

Consistent scores within the 70 to 75 range are considered suggestive of borderline intellectual functioning and may indicate a mental disability. However, it is recommended that multiple test instruments be administered to confirm a diagnosis. No diagnosis should be made on the basis of a single test.

Do People with Borderline Intellectual Functioning Receive State or Federal Services?

In the past, because of the weight is given to IQ scores alone, people with scores between 70 and 75 were generally denied services and supports provided to people with scores below 70.  Today, however, there is more of an emphasis on individuals' ability to function and manage daily living skills. Thus, if an individual has a borderline intellectual disability, he may or may not receive services. The determination will depend on upon a number of factors; for example:

  • What other diagnosis goes along with borderline intellectual disability?  For example, an individual with ​autism and an IQ of 75 may have significantly more difficulty with daily life activities than an individual with the same IQ and ​Down Syndrome.
  • Where does the individual live? Rules regarding agency services vary from state to state.
  • What kinds of supports are available to individual in his living situation?
  • Does this individual have physical challenges that make it difficult for him to perform ordinary life skills? Some genetic disorders which cause lowered IQ can also cause lowered muscle tone, poor coordination, and other issues.

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