Phonological disorders and stuttering in children: what is the frequency of co-occurrence?

In the profession of speech-language pathology, there is a strong belief that phonological disorders frequently occur in children who stutter. The purpose of this article is to examine recently published studies that addressed the frequency with which the two disorders co-occur. Over 10 years ago, a similar article was published in which studies that had been conducted from the 1920s through the 1980s were examined. Unfortunately, methodological problems with the earlier studies limited the conclusions that could be drawn. Because of the uncertainty generated by those studies, researchers since 1990 have continued to investigate this topic. Based on the previous review, it is argued that more rigorous methods are needed, including the use of more objective and comprehensive measures of phonological development and matched control groups of non-stuttering children. The current review indicates that frequency rates vary widely from one study to another, making it difficult to state with confidence just how often the two disorders co-occur. Possible explanations for the discrepancies are discussed, including differences in how phonological disorders are defined and identified. Suggestions are offered for future research to obtain more precise estimates of co-occurrence.