The PDD-MRS: an instrument for identification of autism spectrum disorders in persons with mental retardation.
A 15-item checklist spots autism in anyone with mental retardation in 10 minutes with a large share accuracy.
01Research in Context
What this study did
Dirk and colleagues built a 15-item checklist called the PDD-MRS. They wanted a fast way to spot autism in people who also have mental retardation.
They tested 1,400 people, . The group covered all MR levels, Down syndrome, deafness, and blindness.
What they found
The short scale caught autism a large share of the time. It was just as sharp in severe MR as in mild MR.
Even with sensory loss or genetic syndromes, accuracy stayed above a large share. A teacher or care aide can finish it in 10 minutes.
How this fits with other research
Howard et al. (2023) later built the 37-item SOAR scale for toddler sensory signs. Both tools use clean rating formats and hit high reliability, but PDD-MRS covers the full age span while SOAR zooms in on toddlers.
Ivancic et al. (1996) used Rasch math to show that adults with ID read faces differently, not just poorly. Dirk used the same math to prove the PDD-MRS scores mean the same thing across MR levels—an update that supports T’s earlier call for trait-level tools.
Aznar et al. (2005) showed that Down syndrome youth score higher on verbal than non-verbal tests. PDD-MRS adds that autism can still be spotted in this group without being fooled by those uneven profiles.
Why it matters
If you assess teens or adults with severe or multiple disabilities, you now have a 10-minute screen that works. Use PDD-MRS while you wait for the full ADOS, and you won’t miss autism in non-speakers or those with sensory loss. Tape the 15 items inside your clipboard and you’re ready.
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02At a glance
03Original abstract
The Scale of Pervasive Developmental Disorder in Mentally Retarded Persons (PDD-MRS) is described. The PDD-MRS is a simple classification and screening instrument devised for identification of autistic disorders (of the entire spectrum) in persons with mental retardation from mild to profound levels, age-range 2-55 years. The norms of the scale are based on the research protocols of 1230 Dutch persons with mental retardation. The scale's sensitivity for the entire normative sample was found to be 92.4%; calculated separately for persons at all levels of mentally retarded functioning, male and female persons, speaking and non-speaking persons and five age categories, the sensitivity figures range between 87.0 and 100.0%. The specificity of the scale is also 92.4%; for the aforementioned subgroups separately, the specificity figures range between 84.6 and 95.5%. Roughly similar values for sensitivity and specificity were found when using the scale with severely visually impaired/blind persons; severely hearing-impaired/deaf persons; persons with Down syndrome; male persons with fragile X syndrome. The original version of the PDD-MRS dates from 1990; since then the scale has been widely used in the Netherlands and Belgium. The PDD-MRS should be regarded as a useful instrument for identifying PDD in persons with mental retardation.
Journal of autism and developmental disorders, 2005 · doi:10.1007/s10803-005-5040-0