“Those with intellectual disability or minimal verbal ability are often systematically excluded from research on ASD,” say the researchers, resulting in “limited applicability to people who may need the most support.”
Missing the mark: most studies exclude subjects with severe forms of autism. (Stock photo)
By Jill Escher
A new commentary published in the Journal of Autism and Developmental Disorders stresses that people with more severe forms of autism (focusing on those involving intellectual disability [ID]) “are often systematically excluded from research on ASD,” resulting in a “disparity in who benefits from research.”
The paper, “Making Research Possible: Barriers and Solutions For Those With ASD and ID,” was written by Audrey Thurm, Alycia Halladay, David Mandell, Melissa Maye, Sarah Ethridge, and Cristan Farmer. They say that the severe end of autism requires focused study, particularly around causation and treatment.
The Centers for Disease Control estimates that 31–50% of those with an ASD diagnosis also meet criteria for ID, yet one study estimated that only 6% of participants in ASD research have ID, and another on ASD treatment studies indicated that the rate of inclusion of severely affected children with ASD decreased between 1991 and 2013. Worse, because the cognitive and verbal ability of research participants often goes unreported, these estimates may still not reflect the full extent of the exclusion.
Why is severe autism so often excluded? The authors discuss several factors, including:
Explicit study criteria that exclude people with ID (perhaps due to inherent study aims, or costs and complexities that accompany severe autism).
Implicit exclusion, such as proxies or strong risk factors for ID, such as an identified genetic conditions, a significant neurologic condition, or premature birth.
Methods that may prevent people with ID from participating, owing to their limited ability to read, write, communicate, process directions, and attend for long periods of time.
Assessment tools that have limited validity this population. People with severe-to-profound ID are not represented at all in the standardization samples of many commonly used research measures. Thus, in an effort to maintain the internal validity of a study, researchers may restrict participation to those who can successfully complete a task or measure.
Self-exclusion. Families may have a justified fear of unequal treatment, or of the amount of time, money and effort it takes to prepare for or complete the study; a high general burden in relation to the potential for benefit.
The assessments also may not seem appropriate for the participant.
Real or presumed ethical issues. However, prohibitions on inclusion of the severe may itself be unethical.
The additional effort required to adapt existing consent materials - capacity assessments may be necessary for adults if guardianship is not established.
Bottom line, the authors say, is that “When people with ID are excluded from research, they do not benefit from research,” betraying the needs of the “people who may need the most support.” A focus on severe forms of autism will mean more attention to its unique features, including neurobiology (poorer functional connectivity), etiology, genetics, auditory processing, greater ASD symptom severity, greater likelihood of behavior problems, comorbidities and treatment efficacy.
Finally, the authors share strategies to improve inclusivity and focused study on severe ASD:
Increased flexibility for study engagement to reduce participant and family burden, such as additional staff, equipment, time, and manuals for such adaptations.
Increased workforce training, including clinical training around ID for professionals (e.g., pediatricians, psychologists and psychiatrists), research staff, community liaisons, and others who may work directly on improving research methods for this population.
New methods to increase the participation, compliance, and success of individuals with ID in clinical research (e.g., mobile technology, telehealth, telemetric assessments, use of alternative and augmentative communication), including both standardized and non-standardized measures.
And — most importantly — an overall goal of research that is relevant and useful for people with ID + ASD.
The paper is behind a paywall, link here, but you can read it in manuscript form for free here.
Reference:
Thurm A, Halladay A, Mandell D, Maye M, Ethridge S, Farmer C. Making Research Possible: Barriers and Solutions For Those With ASD and ID. Journal of Autism and Developmental Disorders. 2021 Oct 30:1-5.