From the dozens studies I've read, it seems that research has indeed found differences in white and grey matter (also known as structural neurological differences). However, it seems that research studies are inconclusive when it comes to determining whether these structural brain differences are a cause of stuttering. Additionally: "*The* ***only independently-replicated observations of such disruptions are after stuttering onset****. Therefore, can we be confident that they are part of the* ***effects of stuttering****,* ***not part of its cause?***" - From the research: "Contemporary clinical conversations about stuttering: What does brain imaging research mean to clinicians?" (2024)