Rapid assessment of severe cognitive impairment in individuals with developmental disabilities.
RADD-2 hands you a fast, valid snapshot of cognitive level for clients with severe IDDD when standard tests are too long or hard.
01Research in Context
What this study did
Plant et al. (2007) built a 25-minute test pack for people with severe intellectual disability. The pack is called RADD. It uses easy tasks so even non-speakers can show what they know.
The team gave RADD to a large group with ID or developmental delay. They checked if scores stayed the same when the same person took it twice. They also looked at whether scores matched longer IQ tests.
What they found
RADD scores were steady across two test days. Scores also lined up well with full IQ tests. The tool gave a clear picture of each client's mental level without tiring them out.
No one hit the bottom or top limits of the test. That means RADD works for every level of ability in the IDDD range.
How this fits with other research
Hamama et al. (2021) later made RADD-2. It keeps the 25-minute length but fixes small floor and ceiling issues. Their sample had tougher clients with more medical problems. RADD-2 still held up, so the second edition now replaces the 2007 version.
Perez et al. (2015) used the same 2007 RADD to spot early dementia in adults with Down syndrome. Scores dropped when dementia started. This shows the tool can do double duty: measure base skills and flag decline.
Thomas et al. (2021) tested three other brief batteries for Down syndrome dementia. Their DLD scale also worked, but it is not a replacement. It simply gives you another quick option if you do not have RADD on hand.
Why it matters
If a client cannot sit through long IQ testing, grab RADD-2 first. You get valid data in under half an hour. Use the profile to set baseline skills, write goals, or notice cognitive loss later. The same tool now works for kids, adults, and people with added medical issues.
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02At a glance
03Original abstract
BACKGROUND: Most standardized intelligence tests require more than 1 hour for administration, which is problematic when evaluating individuals with intellectual disabilities and developmental disabilities (IDDD), because a significant proportion of these individuals can not tolerate lengthy evaluations. Furthermore, most standardized intelligence tests are of limited usefulness for individuals with severe cognitive deficits because of floor effects. METHODS: A number of low-difficulty items were selected from standardized tests. A total of 271 participants with profound, severe, moderate and mild levels of cognitive impairment took part in this study. In the formative phase, 68 participants were evaluated with the selected items, and those items that differentiated between levels of cognitive impairment were retained in the battery. The instrument was then modified and standardized with an additional 203 participants. RESULTS: The instrument, referred to as the Rapid Assessment for Developmental Disabilities (RADD), required 10-25 min for administration. Internal reliability estimates from the RADD total score and from individual subtests satisfied conventional and rigorous statistical criteria (median alpha r = 0.93). The RADD total score was strongly correlated with the level of cognitive impairment (rho = 0.86). The RADD total score and individual subtests differentiated between all levels of cognitive impairment ( Wilks Lambda = 0.135, F(42,525.832) = 12.075, P < 0.001). Receiver operating characteristic curves indicated the instrument was particularly sensitive to the cognitive abilities of the most seriously impaired participants. CONCLUSIONS: The RADD, composed of low-difficulty items from published tests, is rapidly administered, assesses a wide range of cognitive skills and differentiates among all levels of cognitive impairment. The battery has clinical utility with populations exhibiting short attention spans because of its ability to quickly assess a wide range of cognitive abilities. The RADD also has research potential for the documentation of cognitive function in studies of individuals with IDDD.
Journal of intellectual disability research : JIDR, 2007 · doi:10.1111/j.1365-2788.2006.00853.x