Useful references for ACL presentations and evidence-based research, in particular, for those working with IDD clients.
Question:
Can you suggest some references that can be used in evidence-based ACL presentations for IDD?
Response:
The Cognitive Disabilities Model (CDM) and the Allen tools (e.g., ACLS/LACLS, ADM, RTI-E) are widely used because they provide a practical, functional cognition lens that translates directly into day-to-day recommendations: task grading, environmental setup, cueing style, supervision levels, and risk mitigation. That “translation to function” is exactly why the model remains highly relevant in contemporary mental health services, and why it is also very applicable when working with consumers who have IDD alongside mental health needs.
1.Evidence-informed use in mental health (and why teams keep coming back to it)
The CDM/Allen approach has a substantial practice and research base in adult mental health settings. Across the literature and longstanding practice, Allen level estimates have been used to support defensible clinical reasoning about functional performance, learning capacity in context, and the type/amount of assistance required.
In practical terms, CDM-supported recommendations are often immediately actionable for inpatient units, community teams, and rehabilitation-focused programs because the outputs are concrete: what the person can do consistently, what they can learn with repetition, what setup reduces risk, and what support is required for safety and follow-through.
2. Applicability to people with IDD (clear clinical fit, especially when the goal is functional planning). From a clinical standpoint, CDM is well suited to IDD work because it is not a diagnostic framework—it is a functional cognition framework. It helps clinicians and teams answer questions that are central in practice with people with IDD, for example:
“What is this person likely to manage reliably in daily life with the right setup?”
“What is the most effective prompting style?”
“What risks increase when task demands exceed current functional cognition?”
“How do we design environments and routines that support engagement, independence, and safety?”
This makes it especially valuable when working with IDD, because it supports realistic goal setting and prevents the common service mismatch of expecting higher-level planning/problem-solving than the person can reliably sustain under stress, symptom fluctuation, or environmental complexity.
A confident and accurate way to phrase it in education materials could be, “CDM/Allen tools are evidence-informed measures of functional cognition with a strong history of use and research in mental health and cognitive impairment contexts. They are highly applicable to consumers with IDD when the purpose is functional planning, support design, risk management, and capacity-building within everyday routines—particularly when combined with occupational performance observation and collateral information.”
Good-practice points (to strengthen confidence and usefulness in IDD presentations)
If using ACLS/LACLS and CDM principles with IDD consumers, it helps to document:
Access prerequisites and supports (vision, fine motor skills, language, anxiety/rapport, sensory needs) so that results reflect cognition rather than barriers to participation.
Triangulation with functional observation (real-world tasks), collateral, and (where relevant) adaptive functioning information.
Direct translation to the care plan: graded task demands, environmental supports, cueing hierarchy, supervision recommendations, and safety planning.
In relation to IDD specifically, there is published psychometric work supporting use of CDM-linked functional cognition assessment in an intellectual disability cohort.
Sim et al. (2015) examined the Routine Task Inventory–Expanded (RTI-E) with 24 clients with intellectual disability and reported very high inter-rater reliability and evidence of construct and criterion validity (via correlations with the EFPT), concluding the RTI-E was valid and appropriate for OT use in that ID population.
In addition, the Allen Cognitive Group has published an IDD-relevant applied case example (“Chris,” Autism Spectrum Disorder with intellectual and developmental disabilities) demonstrating how ACLS-5 and ADM results are translated into concrete intervention planning (task/environmental modification, caregiver instruction methods, and repeated in-context training) leading to safe, functional gains (independent community travel to work).
Broader supporting evidence includes Allen Cognitive Group summaries showing developmental disability represented within mixed-diagnosis participant samples in ACL Screen psychometric research, and a table of intervention outcome studies (1999–2020) where ACLS/LACLS-informed CDM interventions are associated with measurable functional outcomes across mental health and cognitive impairment cohorts (e.g., housing stability improvements in adults with mental illness at risk of homelessness, and reduced challenging behaviours/improved QoL in dementia programs).
The RehabMeasures Database also provides an independent measure summary emphasising that ACLS is best used within a comprehensive functional evaluation and interpreted with consideration of factors such as sensory/motor access and psychiatric symptoms that may influence performance.
The CDM model and associated assessments are considered transdiagnostic. This is covered in the ACLS 5 manual 2nd edition.
References:
Sim, S. S., Hong, K., Kuan, Y. Y., Quek, S. T., & Tan, W. J. (2015). Examining the reliability and validity of RTI-E for use with intellectual disability population in Singapore. Abstract from Asia Pacific Occupational Therapy Conference 2015, Rotorua, New Zealand.
ACLS and LACLS Committee. (2023). Case examples of evaluation and intervention within the cognitive disabilities model [PDF]. Allen Cognitive Group.
Case-Examples-of-Evaluation-and-Intervention-within-CDM_4.2023.pdf
McCraith, D. B. (2023). Participant samples in research studies of psychometric properties of ACL screen [PDF]. Allen Cognitive Group.
Participant-Samples-in-Research-Studies-of-Psychometric-Properties-of-ACL-Screen_-4.2023-.pdf
McCraith, D. B. (2023). Examples of intervention outcome studies based on the cognitive disabilities model [PDF]. Allen Cognitive Group.
Examples-of-Intervention-Outcome-Studies-Based-on-the-CDM_-4.2023-.pdf
Shirley Ryan AbilityLab. (2025, June). Allen Cognitive Level Screen. Rehabilitation Measures Database.