Speech dysfluency and manual specialization in Down's syndrome

The relationship between speech dysfluency and manual lateralization was studied in 31 adults with Down's syndrome. Analysis of speech samples from videotapes indicated that frequency of dysfluency ranged from normal to very severe; 42% of the subjects were stutterers. Manual lateralization was measured by the demonstrated use of five objects (pencil, comb, toothbrush, ball and scissors); 61% of the subjects had a clear right-hand preference, 13% a left-hand preference, and the remaining subjects (39%) were mixed-handed. Increased dysfluency was associated with increased non-right-handedness, and this finding could not be explained by reference to either generalized linguistic or intellectual deficits. Results suggest individual variation in the speech motor control system in adults with Down's syndrome which may be associated with anomalous cerebral dominance.