Family history as a basis for subgrouping people who stutter.

Of a clinical population of 169 adult and adolescent stutterers, 112 members (66%) reported a family history of stuttering. Only 3 (2.4%) of these reported any birth or early childhood factors or events that were thought to be associated with stuttering onset or that potentially might have precipitated stuttering. In contrast, 21 (37%) of the 57 members without a family history of stuttering reported such a factor or event. On the basis of this retrospective investigation of family history, the stutterers could be segregated in ways that may be informative relative to etiology and underlying mechanisms despite being apparently similar with respect to time of stuttering onset, dysfluency characteristics, and emotional concomitants. It is suggested that these data are consistent with a hypothesis that within the clinical population of adults presenting as developmental stutterers there are really two subgroups. One subgroup is thought to consist of individual with a genetically inherited predisposition for stuttering, and the second of individuals without such a predisposition but who may have sustained some form of early brain damage. The incidence of false negatives in the 36 individuals classified as having no family history and no known early physical trauma remains to be ascertained. Implications for research on both brain mechanisms of stuttering and responsiveness to clinical treatment and fluency maintenance are discussed.