More than 80 million people worldwide, including President Joe Biden and singer-songwriter Ed Sheeran, experience stuttering, a condition that affects the fluency and timing of speech. People who stutter may repeat sounds, syllables or words; may prolong sounds; and may experience interruptions or blocks in speech. Stuttering can interfere with a person's daily life, by triggering anxiety around social situations, for example.
Despite the high prevalence of stuttering, scientists still don't know a lot about what causes it — at least in most cases. There's not enough evidence to definitively explain the neurobiology of stuttering, Elina Tripoliti, a clinical specialist speech and language therapist at University College London, told Live Science. The current consensus among researchers is that the condition is likely caused by a mixture of factors, including genetics, differences in brain structure and function, and a person's environment.
