A Physiologically Integrated Approach to Studying Mechanisms of Speech Production and Swallow Function in Down Syndrome

Abstract Individuals with Down syndrome (DS) have substantively heightened risk of swallowing difficulties, leading to associated risk of aspiration of food or liquid and possible pneumonia. The speech of virtually all of these individuals can be difficult to understand by unfamiliar listeners, leading to restrictions in ability to participate in virtually all valued activities, from educational to vocational, social, community, and self-advocacy activities. Production of both swallow and clear speech rely on the structures and functions of the oral mechanism as well as their neural underpinnings. The phenotype in DS includes a spectrum of well-established dysmorphologies in oral-pharyngeal structures and functions, in cognitive and linguistic abilities, and most likely in neural substrate as well. Current swallow and speech interventions for individuals with DS largely rely on recommended clinical practice approaches that are “borrowed” from other populations, such as individuals with speech sound disorders or apraxia. Yet such individuals rarely present with the syndrome-specific structural and functional oral-pharyngeal and cognitive/linguistic dysmorphologies seen in most if not all individuals with DS. It is possible—even likely— that these interventions may therefore not be optimal for individuals with DS, given that they were not designed to take into consideration the unique phenotypic profiles in DS. A biophysiologically integrated study of the affected domains and the relationships between them is needed to understand the nature of impairments in DS and optimize clinical interventions. The proposed project will examine the mechanisms of swallow and speech production directly within the context of the documented phenotypic characteristics in DS. Specifically, we will examine the interrelations between domains of oropharyngeal structure, muscle strength, somatosensation, measures of cognition, perception and language, and the underlying neurology in terms of how each relates to the execution of the oral motor behaviors of swallow and speech production. The research team brings together experts across each of the planned domains, all at the same institution, led by a PI whose career has been dedicated to application of innovative measurement techniques to individuals with intellectual and developmental disabilities, including DS.