Thiamine. Effective or not?

Thiamine. Effective or not? I recently read here that the Ashwagandha + L-Theanine combination has helped many people gain significant fluency, however, my speech therapist suggested to me that Thiamine may help, even more so accompanied by Magnesium, I had not heard this before and wanted to know if any of you tried it and what your results were. Thank you.