A new, multi-site study has concluded that Expressive Language Sampling (ELS) is a useful tool for measuring communication development in young adults with Down syndrome.
The study, co-led by Angela Thurman and Leonard Abedotto of the UC Davis MIND Institute and Department of Psychiatry and Behavioral Sciences, focused on language as an outcome measure for discovering meaningful changes in communication skills of individuals with Down syndrome. Successfully tested and validated ELS as a reliable set of procedures for collecting, measuring, and analyzing the spoken language of participants interacting in a natural environment.
Down syndrome and language delay
Down syndrome is the main genetic cause of intellectual disability. One in 700 children in the United States is born with Down syndrome. Individuals with Down syndrome often experience speech and language delays that can severely affect their independence and successful socialization.
“Interventions that lead to improvements in language will have major impacts on the quality of life of individuals with Down syndrome,” said Abeduto, director of UC Davis MIND, professor of psychiatry and behavioral sciences and lead author of the study. “To develop and evaluate such interventions, we need an accredited measurement tool and ELS provides that.”
The ELS procedure
During an ELS procedure, researchers collect samples of participants’ speech during two types of natural interactions: conversation and narration.
In conversation, trained examiners engage participants on a variety of topics in a sequential, standardized manner. They start the conversation with a topic that participants find interesting and then introduce a topic from pre-defined age-appropriate lists. In their interactions, they follow a script to reduce their participation and maximize the contribution of the participants. On average, the conversation takes about 12 minutes.
In narration, participants independently form and tell the story in a wordless picture book. This process usually takes 10 to 15 minutes.
Researchers analyze collected conversation and narration samples. In a previous ELS application involving participants with Fragile X Syndrome, the researchers derived five measures of language outcome: chatter, lexical diversity (vocabulary), sentence structure, fluency impairment (verbal planning), and lack of clarity (verbal expression).
Validity and reliability of ELS measures in studies of Down syndrome
In this study, four university test sites recruited 107 participants with Down syndrome (55 males and 52 females). Participants were between 6 and 23 years old (average age 15.13) and IQ levels less than 70 (average IQ 48.73).
Participants came on the first visit to complete ELS procedures and to take tests that assess their IQ, severity of autism symptoms, and other measures. Four weeks later, they revisited the ELS procedures. This retest was to assess the effects of practice on repeated administrations and to check the reliability of ELS metrics.
The study found that the ELS measures were generally correct and reliable across ages and IQ levels. It showed that the variables of vocabulary, syntax, and clarity of speech showed strong validity as outcome measures. Also, ELS procedures were possible for the majority of participants who successfully completed the tasks. Young people under the age of 12, who had a phrase-level speech or less, and whose level of development was 4 years of age or younger, found it more difficult to complete it.
“Spoken language is the primary way in which we interact with the people around us, which makes language a frequent target for therapy. However, we did not have tools sensitive and accurate enough to confidently measure change in language therapy studies,” said Thurman, associate professor of psychiatry and first author. In the study. “The data from this study provides a critical first step that indicates that these measures can be used to effectively measure language for people with Down syndrome.”
The study, published April 8 in Journal of Neurodevelopmental DisordersAvailable online. Researchers provided online evidence to assist other investigators with administration, training, and evaluation of the accuracy of ELS procedures.
This study was co-authored by Jimmy O. Edgen of the University of Arizona, and Stephanie L. Sherman and Debra Hamilton from Emory University, Audra Stirling from the University of Wisconsin-Madison, Elizabeth Perry-Kravis from Rush University Medical Center, and Andrea McDuff, University of California at Davis Health.
It was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (R01HD074346, P50HD103526) and the National Center for Transformational Science Development (UL1 TR000002).
The study: Thurman et al. “Spoken language outcome measures of treatment studies in Down syndrome: feasibility, practice effects, test-retest reliability, and validity of variables resulting from sampling of expressive language,” Journal of Neurodevelopmental Disorders. DOI: 10.1186 / s11689-021-09361-6
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