From Mental Retardation to Intellectual Disability

This post is part of a series of guest posts on GPS by the graduate students in my Psychopathology course. As part of their work for the course, each student had to demonstrate mastery of the skill of “Educating the Public about Mental Health.” To that end, each student has to prepare three 1,000ish word posts on a particular class of mental disorders, with one of those focusing on changes made from the DSM-IV to the DSM-5.

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From Mental Retardation to Intellectual Disability by Trisha Shanbour

Since the 1990s, when it was used as the official diagnostic label in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), the term “mental retardation” has transformed from being a term used for a small portion of the population with severe cognitive deficits to one that is instead derogatory and used in everyday language to call someone or something “stupid”. It is because of this negative connotation that persons with mental retardation, their families, and researchers advocated for the diagnostic term of intellectual disability instead of mental retardation. This has finally occurred, along with several other key changes, in the recently released DSM-5.

While the name change from mental retardation to intellectual disability was the most noticeable change in this category, there were other criteria-based changes that actually impact this disorder’s diagnosis much more than the name. In the DSM-TR-IV, level of intellectual functioning was mainly based on the IQ score someone received after an individually administered intelligence test (such as the Wechsler or Stanford-Binet families of tests). The other diagnostic criteria were deficits in adaptive functioning and an onset of symptoms prior to age 18. The IQ score, though, tended to weigh most heavily on a professional’s decision to diagnose a person with mental retardation

There was much discussion before the new DSM was released about how IQ testing alone may not adequately assess whether a person has low intellectual functioning. As an alternative, it was argued that adaptive functioning is more important than IQ alone, as adaptive functioning consists of the skills one needs to live life to the fullest, learn about the world, and be functional in the greater society.

Within the DSM-5, the criteria have indeed shifted, as research has shown the importance and significance of adaptive functioning. In the new DSM, this criteria is based on intellectual functions, such as reasoning and problem solving. Then, within the text, IQ scores, which still have to be a part of the diagnosis, are discussed, although professionals can now decide how much the IQ score really matters within each case. The other criteria changes deal with deficits in adaptive functioning in three domains (conceptual, social, and practical) and then specifying that the onset of the disorder needs to be during the developmental period, not just prior to age 18. These shifts give a lot more room for the mental health professional to judge the mental capacity of the individual vs. having a stricter guideline like in the DSM-TR-IV.

The age of onset is something else to consider when addressing changes. Within the DSM-TR-IV, the age of onset for diagnosis was simply before 18 years old. With criteria like this, many people were being classified with an intellectual disability when really it wasn’t one. For example, if a person, age 16, were to get in a car wreck and have some type of head/brain injury resulting in cognitive impairment, this should not be considered an intellectual disability but instead a diagnosis of “other specified neurodevelopment disorder” would be given. The criteria in the DSM-5 is important because about 30-40% of intellectual disabilities have genetic or biological causes and thus should be seen in early childhood (the development period) or when the child starts school.

Another change in the DSM-5 is the description of the severity levels. Although there are still mild, moderate, severe, and profound categories, the descriptions have changed from being based on IQ score ranges to instead being adaptive functioning descriptions. This actually might make diagnosis harder to do for clinicians and may decreasing the number of persons with an intellectual disability. Why? Because it is much easier to classify someone based on a score, one single number (like an IQ score), than it is to figure out what conceptual, social, and practical skills a person has. One would have to gain more background information on an individual before a diagnosis could be given.

Are these changes from the one DSM to the other good or bad? Clearly, some changes needed to occur, particularly the wording used to describe this diagnosis. The word “retard” has spun into a world of negativity and bullying over the past 30 years and needed to be removed from the official diagnostic lexicon (just has happened in the past when official terminology shifted from “idiot, imbecile, moron” to “mental retardation”). The criteria changing to put more emphasis on adaptive functioning and less on IQ scores is, in most people’s eyes a positive change. Yet, there are some that say that this change could turn out badly because there is more room for error. The age of onset change makes intuitive and clinical sense since, if someone truly has an intellectual disability they will show signs during the developmental period. Also, by changing these criteria to the developmental period helps to emphasize that early intervention is the best intervention (which holds true for all neurocognitive disorders). Lastly, the severity levels are no longer based on IQ scores but based on the three domains of adaptive functioning. This again, could have good and bad results, as a) it could be a better assessor of the persons intellectual abilities (which the research shows) and/or b) it is more difficult to assess a person and a lot more time goes into assessment before a diagnosis is given.

There is also one more thing to note about the DSM-5’s coverage of intellectual disability that is important, namely where is all the background information? If you look at the DSM-TR-IV there is more research, numbers, statistics, and data within the context of each disorder (including intellectual disabilities) than in the DSM-5. It’s quite funny to think that if you want to get statistical numbers on a disorder, you would have to go to the old addition of a book than the new. This seems to be at least partially due to the haste with which this new edition was published, which did not provide time for thorough field trials of all the changes.

Overall, the diagnostic changes from the DSM-TR-IV to the DSM-5 for the category of intellectual disabilities would get an “A-” from me. The minus primarily reflects that, although they got all the changes needed to keep up with society, the lack of detail and information are quite troubling. The lack of detail and background research raises the questions: How reliable is this diagnosis? What research supports the diagnosis? Could a better DSM-5 have been made if the publishers gave the system more time?