Last fall I reported on a phenomenon that doctors around the globe were just beginning to understand: Teen girls were showing up in hospitals and clinics with sudden motor and verbal tics seemingly related to videos they watched on TikTok.

Doctors say they’re continuing to see an outsize number of girls suffering from tics, and some are also developing new disorders.New research findings offer hope that the problems can be addressed.

Starting back in the spring of 2020, girls in Chicago were uncontrollably blurting out the same words as girls in Calgary. Doctors from the U.S. to the U.K. discovered that many of the teens had been watching TikTok videos of people who said they had Tourette syndrome, a nervous-system disorder that typically strikes males during early childhood and causes them to make repetitive, involuntary movements or sounds.