A systematic review on the role of language-related factors in the manifestation of stuttering in bilinguals

Purpose: Bilingual(s) who stutter (BWS) provide an opportunity to explore the link between stuttering and language. Unlike in monolinguals, stuttering in bilinguals could be influenced by both speaker-related language (e.gs. dominance & proficiency) and linguistic typology-related factors (e.g., structure of languages). However, the available literature is largely inconclusive on these factors. In this context, we systematically reviewed the literature to compile evidence on the influence of such factors on BWS. Method: We followed the conventional systematic review process that included five databases. Further, the quality of the included articles was assessed using Newcastle-Ottawa Scale (NOS) for quality rating. Result: Thirteen articles passed the selection criteria. Review of these articles revealed that language proficiency and dominance are the important factors that affect stuttering frequency in BWS. Though the linguistic typology is portrayed as a factor on the differential manifestation of dysfluencies in both languages of the BWS, the literature does not provide substantiating data for this. Further, the lack of uniformity in assessing and reporting language dominance and proficiency are the major drawbacks in the existing literature on stuttering in BWS. Conclusion: This review identifies proficiency and dominance as the major factors that influence the stuttering frequency in BWS. Currently, the evidence for the influence of typological differences between languages of the BWS on stuttering largely remains whimsical. Future research shall employ the recommended tasks and metrics while assessing the dysfluencies in BWS so that findings across centres become comparable, which in turn, could yield valid inferences.