Speech sound disorders (SSD) are the most prevalent type of communication disorder in early childhood and often place an individual at risk for later academic difficulties. Despite the high prevalence of SSD, there have been no large, longitudinal studies of SSD extending from early childhood into adolescence/young adulthood to examine residual speech/language deficits and long-term consequences for educational/vocational attainment and behavioral adjustment. The present proposal is a continuation of a 20 year genetic study of SSD (A Familial Study of Severe Phonology Disorders;NIDCD grant number DC000528) that seeks to validate the role of known genes for SSD and co-morbid language impairment (LI) and reading disorders (RD). This project will exploit the large database of families with SSD assembled by the investigators to examine long-term outcomes of early childhood SSD and factors that place individuals at greatest risk for later educational and behavioral problems. We have examined 275 families of children with early childhood SSD and followed 284 of these children to school age. In this project, the sample will be reassessed in adolescence/young adulthood on measures of LI, RD, and associated cognitive skills, or endophenotypes that have been linked to specific chromosome regions. DNA has been provided by 463 sibling pairs and we have conducted model-free genetic linkage analysis for binary and quantitative traits. We have found evidence for linkage of phonological processing to 3p12-q13 and 6p22-p21.2, speech sound production to 15q15-q21, verbal short-term memory to 1p36 and language skills to 1p33-p32. These linkage studies suggest that the underlying genes influence the behavioral and genetic overlap of SSD, RD, and LI and we test the hypothesis that neurally expressed genes identified for dyslexia are also associated with SSD. Measures of adaptive functioning, psychosocial adjustment and educational/vocational attainment will also be employed to examine the functional significance of early SSD in adolescence/young adulthood. These outcomes will be related to the presence or absence of co-morbid LI during childhood, persistent vs. recovery of SSD at early school age, specific cognitive deficits, and genetic factors. The interrelationships of these factors will be examined within a structural equation model. Findings will reveal the types of long-term problems to which individuals with early SDD are vulnerable, identify risk factors, and determine needs for adolescent/young adulthood interventions to reduce core problems in language and achievement and insure more favorable educational, vocational, and behavioral outcomes.
Speech sound disorders (SSD) are highly prevalent in children and have high personal and societal costs. More than half of children with SSD encounter later academic difficulties in language, reading, and spelling and often require other types of remedial services, with 50%-70% exhibiting general academic difficulty through grade 12. Recent evidence suggests that the residual effects of an early childhood SSD may be life-long. Language and literacy play a role in independent functioning in the adolescent/young adult. Lack of such independence has a high personal and societal cost. The importance of communication and information skills and technologies in the work place will continue to increase in the future;and the individual who has a communication disorder will thus be at a disadvantage in this regard. An individual's future occupational success can be enhanced through the early identification of communication disorders, establishment of their causes, and subsequent intervention. Little is known of the transition into adulthood by the individual with a history of SSD. This project will provide life-span data that is needed to determine full significance of early SSD for the later functioning of this population and identify factors that influence adolescent/young adult outcomes.
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