By Anne Foundas, M.D.,
Professor of Neurology,
Department of Psychiatry and Neurology,
Tulane University Health Sciences Center,
New Orleans, Louisiana.
Individual hand preference has not been extensively studied in developmental stuttering despite the longstanding hypothesis that developmental stuttering may be associated with atypical cerebral laterality. Atypical hand preference may be a marker of atypical cerebral laterality or atypical brain dominance. There is recent research evidence that individual footedness is also important to study and may help in examining individual laterality. Our research group at Tulane University Health Sciences Center has been interested in studying the biological basis of developmental stuttering including an analysis of hand preference.
The Stuttering Foundation distributed handedness questionnaires in the summer of 2003. We had an overwhelming response from individuals in the United States and from around the world. We have conducted some preliminary analyzes of these data, and have some interesting results. Over 1000 questionnaires were received and entered into a database. In this sample, 56% of the participants reported that they were currently stuttering, and 44% had previously stuttered. In the group with persistent stuttering, the proportion of men to women was 5 to 1, a finding that is consistent with results reported in the literature. As far as handedness, we found that overall the proportion of right and left handers, defined by writing hand, was similar to that reported in the general population. That is, about 90% of the participants were right-handed and 10% were left-handed.
The hand preference questionnaire, however, allows us to look at another dimension of handedness degree of handedness.
Based on responses to questions of hand use derived from a standardized questionnaire, individuals can be defined as consistently right-handed, mixed (right or left-handed) and consistently left-handed. Handedness can also be defined along a continuum. In our study we found an interaction of handedness and gender. That is, the women with developmental stuttering were more mixed in handedness compared to the men who did not differ significantly from people who do not stutter. There were, however, more men in the left-handed group. Reponses to the footedness questionnaire did not show any group differences.
We are continuing to analyze these data in order to determine if specific items in the questionnaires may be linked to degree of handedness and to other variables that we examined, including family history of stuttering and family history of left-handedness.
We greatly appreciate the response and the assistance from the administrative staff at the Stuttering Foundation of America.