The authors of this study reported that the dysfluencies in the speech of adults with intellectual disabilities and poor intelligibility show patterns that are specific for this population, and that the results suggest that in this specific group of dysfluent speakers interventions should be aimed at cluttering rather than stuttering.
Marjolein C. Coppens-Hofman, Hayo R. Terbanda, Ben A.M. Maassen, Henny M.J. van Schrojenstein Lantman-De Valk, Yvonne van Zaalen-op’t Hof, and Ad F.M. Snik. (2013). Dysfluencies in the speech of adults with intellectual disabilities and reported speech difficulties. Journal of Communication Disorders. http://dx.doi.org/10.1016/j.jcomdis.2013.08.001