According to a case report presented by investigators of the Medical University of Warsaw, Poland, and the Medical School of Hannover, Germany, the use of cannabis may be helpful in the treatment of stuttering. They presented the case of a 20-year-old male with treatment-resistant stuttering, who markedly improved after treatment with medicinal cannabis.

Besides improved speech fluency as assessed by several phoniatric tests, the investigators observed remission of (social) anxiety, improved mood, and reduced stress, resulting in an overall improvement of quality of life after cannabis therapy. The patient, in addition, reported improved attention, concentration, and sleep, increased self-confidence, and better social life. Over a time period of more than a year, treatment was equally effective.

https://pubmed.ncbi.nlm.nih.gov/34314602/