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by Dennis Drayna, Ph.D. (Summer 2007)

Age is among the strongest risk factors for stuttering with several important implications. Although the disorder begins within a wide age-range, current robust evidence indicates that, for a very large proportion of cases, it erupts during the preschool period. Data obtained at the University of Illinois Stuttering Research Program revealed that for 65% of the child participants, stuttering onset occurred prior to age 3; the figure rose to 85% by 3 1/2 years of age (Yairi & Ambrose, 2005). Leaving room for some sampling errors, children past age 4 face a relatively low risk for stuttering. From clinical considerations, these statistics call for greater emphasis on preparing clinicians for working with early childhood stuttering.

by Ehud Yairi, Ph.D. (Fall 2006)

Research advances in genetics are in the news almost every day. Many of these news reports tell of the discovery of a gene that causes a disease or other medical problem. While these reports are often exciting and provocative, it is often not easy to understand exactly what has been discovered and how that discovery will help the people with that disorder. There are a number of studies on the genetics of stuttering now in progress. Findings from these studies are beginning to appear, and there is much hope that more discoveries, telling us more important information about stuttering, will soon be made. What exactly are these studies, and what do scientists hope to learn from them?

by Dennis Drayna, Ph.D. (Summer 2006)

by Per Alm, Ph.D., University of Alberta (Winter 2006)

At this juncture neuroscientists believe that developmental stuttering is a complex motor speech disorder with a strong genetic link. Based on converging evidence from cognitive-behavioral, genetic, neurophysiological and neuroanatomical studies, we have learned that it is likely that stuttering does not result from one causative factor. Furthermore, there is increasing evidence that biological subtypes may be demonstrable with the potential that different therapies may benefit different biologically specific types of stuttering. In a series of recent studies our research group has focused on the anatomy and functional representation of the auditory system in individuals with developmental stuttering.

by Ehud Yairi, Ph.D., University of Illinois (Fall 2005)

by Anne Smith, Ph.D., Purdue University (Summer 2005)

In a recent conference on stuttering sponsored by the National Institute on Deafness and Other Communication Disorders (NIDCD), I discussed several factors related to predisposition to stuttering. These include (a) occurrence, (b) age, (c) gender, (d) genetics, (e) stressors, (f) concomitant disorders, (g) persistency-recovery, and (h) subtypes.

In the last decade, accumulating evidence from laboratories in the U.S. and Europe, as well as our own, led to the development of a multi-factorial model of stuttering. This model of stuttering hypothesizes that stuttering emerges from complex interactions among factors including genetics, language processing, emotional/social aspects, and speech motor control. Ultimately, stuttering occurs when the neural signals that produce the coordinated movements in the respiratory, vocal, and articulation systems become disrupted. The underlying notion is that the functions of the brain areas for speech motor control are affected by complex interactions with other neural systems. One important underlying assumption of this model is that these factors may not play the same role in different individuals who stutter and very likely vary in significance over different stages of development.

By Anne Foundas, M.D.