Stuttering affects nearly 1% of the population worldwide and often has life-altering negative consequences, including poorer mental health and emotional well-being, and reduced educational and employment achievements. Over two decades of neuroimaging research reveals clear anatomical and physiological differences in the speech neural networks of adults who stutter. However, there have been few neurophysiological investigations of speech production in children who stutter. Using functional near-infrared spectroscopy (fNIRS), we examined hemodynamic responses over neural regions integral to fluent speech production including inferior frontal gyrus, premotor cortex, and superior temporal gyrus during a picture description task. Thirty-two children (16 stuttering and 16 controls) aged 7–11 years participated in the study. We found distinctly different speech-related hemodynamic responses in the group of children who stutter compared to the control group. Whereas controls showed significant activation over left dorsal inferior frontal gyrus and left premotor cortex, children who stutter exhibited deactivation over these left hemisphere regions. This investigation of neural activation during natural, connected speech production in children who stutter demonstrates that in childhood stuttering, atypical functional organization for speech production is present and suggests promise for the use of fNIRS during natural speech production in future research with typical and atypical child populations.

Over the past 10 years, we (the Purdue Stuttering Project) have implemented longitudinal studies to examine factors related to persistence and recovery in early childhood stuttering. Stuttering develops essentially as an impairment in speech sensorimotor processes that is strongly influenced by dynamic interactions among motor, language, and emotional domains. Our work has assessed physiological, behavioral, and clinical features of stuttering within the motor, linguistic, and emotional domains. We describe the results of studies in which measures collected when the child was 4 to 5 years old are related to eventual stuttering status. We provide supplemental evidence of the role of known predictive factors (e.g., sex and family history of persistent stuttering). In addition, we present new evidence that early delays in basic speech motor processes (especially in boys), poor performance on a nonword repetition test, stuttering severity at the age of 4 to 5 years, and delayed or atypical functioning in central nervous system language processing networks are predictive of persistent stuttering.

Purpose The purpose of this study is to document disfluency behaviors expressed by 4- and 5-year-old children who stutter and to identify whether stuttering characteristics at this age are predictive of later stuttering recovery or persistence. Method We analyzed spontaneous speech samples from 47 children diagnosed with developmental stuttering when they were 4–5 years old. Based on their eventual diagnosis made the final year of participation in the longitudinal study when the children were 6–9 years old, the children were divided into two groups: children who eventually recovered from stuttering ( n = 29) and children who were persisting ( n = 18). We calculated a composite weighted stuttering-like disfluency (SLD) index of overall severity that considers the frequency, type, and number of repetition units of SLDs. The frequency and type of typical disfluencies were also examined. Results Higher weighted SLD scores at ages 4–5 years were associated with a higher probability of persistent stuttering. The weighted SLD also significantly discriminated between children who would eventually be diagnosed as persisting or recovered from stuttering. The frequency and type of typical disfluency did not distinguish the two groups of children; however, children who were persisting had significantly higher frequencies of part-word repetitions and dysrhythmic phonations (i.e., blocks, prolongations, and broken words) and maximum number of part-word repetitions compared to children who eventually recovered from stuttering. Conclusions Previous findings in younger, 2- to 3-year-old children who stutter did not suggest a relationship between the severity and type of children's SLDs and their eventual stuttering outcome. Yet, by the age of 4–5 years, we found that the weighted SLD, a clinically applicable tool, may be used to help identify children at greater risk for stuttering persistence. We propose that the weighted SLD be considered, along with other predictive factors, when assessing risk of stuttering persistence in 4- and 5-year-old children who are stuttering.