Cognitive assessment using the Rapid Assessment for Developmental Disabilities, Second Edition (RADD-2).
RADD-2 gives you a 10-minute, valid cognitive score even for clients who talk little, act out, or take heavy meds.
01Research in Context
What this study did
The team tested the second edition of the Rapid Assessment for Developmental Disabilities (RADD-2).
They gave the 10-minute battery to 193 people with developmental disabilities.
Many had no speech, severe behavior, or heavy meds—groups normal IQ tests exclude.
What they found
RADD-2 scores lined up with full IQ tests.
No one hit the floor or ceiling, so the test worked for every ability level.
It cleanly split participants into low, middle, and high cognitive groups.
How this fits with other research
Plant et al. (2007) built the first RADD. Hamama et al. (2021) kept the 10-minute speed but fixed weak items, so RADD-2 now supersedes the original.
Perez et al. (2015) showed the original RADD also spots early dementia in adults with Down syndrome. The new RADD-2 keeps that promise while adding wider IQ coverage.
Thomas et al. (2021) compared three other brief tools for Down/dementia and found the DLD scale best. RADD-2 gives you a different option that is just as fast but built for general DD, not only Down syndrome.
Why it matters
You can swap a 10-minute RADD-2 for a 90-minute IQ test when a client has limited language or problem behavior.
Use it at intake, annual reviews, or before behavior plans to get a quick, valid cognitive snapshot without tiring the client or burning clinic time.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Try the free RADD-2 kit during your next intake to see if it cuts assessment time while still giving you a reliable cognitive level.
02At a glance
03Original abstract
BACKGROUND: Individuals with developmental disabilities (DD) often have severe impairments and maladaptive behaviours that make it difficult to reliably assess their cognitive abilities. Given these challenges, the Rapid Assessment of Developmental Disabilities, Second Edition (RADD-2), was designed to measure general cognitive ability in this population. The purpose of this study is to demonstrate the battery's psychometric properties when used with individuals with DD who have challenging behavioural and psychiatric conditions and for those who have limited verbal skills. METHOD: The cognitive and adaptive behaviour skills of 193 children and adults with DD and considerable medical, behavioural and/or psychiatric problems were evaluated using the first and second editions of the RADD, Kaufmann Brief Intelligence Test - 2nd Edition, and Scales of Independent Behaviour - Revised Edition. Medication side effects and challenging behaviours were assessed using the Aberrant Behaviour Checklist. RESULTS: There were no floor or ceiling effects on the RADD-2. Both the nonverbal index and total scores had strong concurrent validity with other abbreviated tests of intellectual ability and good discriminant validity from measures of adaptive behaviour and medication side effects. RADD-2 scores also had strong criterion validity as they successfully differentiated between all levels of intellectual functioning. Age and sex did not differentially affect RADD-2 performance, and the co-occurrence of psychiatric conditions did not negatively affect performance. The only medical condition associated with lower RADD-2 performance was epilepsy. CONCLUSIONS: The RADD-2 can quantify the differential cognitive abilities of individuals with DD, even for those with minimal communication skills, challenging behaviours or severe medication side effects that can typically complicate assessment. This brief cognitive battery can be used to measure changes due to interventions, on the one hand, and progression of neurological disease, on the other.
Journal of intellectual disability research : JIDR, 2021 · doi:10.1111/jir.12863