By Ehud Yairi, Ph.D., University of Illinois
Gender is one of the strongest predisposing factors for stuttering in that the disorder affects many more males than females. In older children and adults the male-to-female ratio is large, about 4 to 1 or greater (Craig, et al., 2002). Except for the higher incidence, until recently no major gender differences, either in speech or other characteristics associated with the disorder have been demonstrated. Interestingly, however, in preschool children close to stuttering onset, several studies have shown considerably smaller gender ratios, only 2:1 (Yairi & Ambrose, 2005), and 1:1.6
(Kloth, et al. 1995; Mansson, 2000).
Although in the past it was suspected that the age-related substantial decrease in the proportion of females who stutter may be due to processes of natural recovery, data obtained at the University of Illinois' Stuttering Research Program on early childhood stuttering have provided strong evidence to this effect.
On the basis of systematic follow-ups of many children over several years, our direct observations established that, indeed, boys have greater risk for developing chronic stuttering. Conversely, girls who begin stuttering have a greater chance than boys to experience natural recovery (without treatment). Specifically, among children who recovered there were 2.3 boys to each girl; in children who became chronic stutterers there were 3.75 boys to each girl. The clinical implications for early risk assessment are obvious.
We have long suspected that underlying the gender ratio in stuttering are genetic factors (likely affecting brain structures associated with speech-language processes). For example, in families of children who stutter, more fathers stutter than mothers and more brothers stutter than sisters. Most recently, Cox et al. (2005) carried this a step further reporting gender differences in chromosomal signals for stuttering. An extremely interesting intersection of findings is seen here: (a) gender in stuttering is genetically influenced ? (b) gender is a factor in natural recovery and chronic stuttering ? (c) natural recovery and chronic stuttering are genetically influenced (our study by Ambrose, Cox, & Yairi,1997). Hence, the disparity in sub-populations is likely to provide a window to the understanding of stuttering, its cause, and amelioration. All in all, the gender factor in stuttering is viewed
as a priority research target.
Cox, N., Roe, C., Suresh, R., Cook, E., Lundstrom, C., Garsten, M., Ezrati, R. Ambrose, N., & Yairi, E. (2005). Chromosomal signals for genes underlying stuttering. Presented at the Oxford Disfluency Conference, Oxford University, Oxford, United Kingdom.
Ambrose, N., Cox, N., & Yairi, E. (1997). The genetic basis of persistent and recovered stuttering, Journal of Speech, Language, and Hearing Research, 40, 567-580.
Craig. A, Tran, Y., Craig, M. & Peters, K. (2002). Epidemiology of stuttering in the communication across the entire life span. Journal of Speech, Language, and Hearing Research, 45, 1097-1105.
Kloth, S., Janssen, P., Kraaimaat, F. & Brutten, G. (1995). Speech-motor and linguistic skills of young stutterers prior to onset. Journal of Fluency Disorders, 20, 157-170.
Mansson, H. (2000). Childhood stuttering: Incidence and development. Journal of Fluency Disorders, 25, 47-57.
Yairi, E., & Ambrose, N. (2005). Early childhood stuttering. Austin, TX: Pro-Ed, Inc.