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Dr. Laura Renteria Answers a Claim Adjuster's Question:
Question:
Knowing a worker has a pre-existing diagnosed mental deficiency (i.e., Down’s Syndrome) would you still administer and interpret standardized testing in the same way and, if not, what cognitive test would you recommend?
Answer:
Laura Renteria Ph.D., ABPP Neuropsychologist
In order to determine whether cognitive decline has occurred, a neuropsychologist must establish a person’s baseline (or premorbid functioning). There is a vast body of research establishing methods to determine baseline functioning, including the administration of certain cognitive tests and the application of statistical formulas, that take into account demographic information.
These methods all assume the person was once capable of normal cognitive functioning and thus cannot be applied to individuals with an intellectual disability (ID). Cognitive testing for workers with intellectual disabilities needs to be treated differently.
Establishing the baseline functioning of someone with ID is one of the most challenging aspects of assessment. This population is very diverse, with a wide range of pre-existing abilities and levels of independence. Available academic records and collateral interviews can be quite helpful in this regard.
In selecting appropriate tests, the neuropsychologist must consider a number of characteristics such as levels of literacy and numeracy, auditory language comprehension, preferred methods of communication, and the presence of physical or sensory impairments that may interfere with testing.
Many of our typical neuropsychological tests are not appropriate as they often require abilities that individuals with an ID never had. As a result, floor effects may be observed, especially in individuals with more severe intellectual disabilities. A floor effect occurs when test items are so challenging that an examinee is unable to answer even the least difficult items. As a result, the information derived from that test is not very meaningful or informative.
Recommendations
When choosing tests the neuropsychologist must look at the research to determine if there is any normative data that can be applied to the individual with ID that is being assessed. Normative data (which helps us score a test) is often based only on samples of healthy volunteers. In recent years, some tasks have been simplified for use with individuals that have an ID.
Examples of these include the Stroop Test, Tower of London, and verbal fluency. These adaptations have incorporated changes to the test instructions, test stimuli, and scoring criteria. They have also included individuals with ID in the normative sample.
Along with cognitive testing for workers with intellectual disabilities, looking at changes in independent functional ability can also help assess change after a brain injury. The perception of decline should depend on the environmental demands that existed on that individual before the work injury.
Caregivers and family members are important sources of information who can comment on an individual’s past abilities and any observed changes in everyday functioning. In some cases, these changes can also be substantiated by available records. In addition, functional abilities can be assessed with tests like the Independent Living Scales and Texas Functional Living Scale.
Dr. Laura Renteria is a native Spanish speaker, is licensed to practice in Oregon, and is board-certified in clinical neuropsychology by the American Board of Professional Psychology (ABPP). She enjoys teaching and currently supervises graduate students who are on assessment practica.
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