Doctors around the globe have reported seeing a baffling surge in the number of teenage girls seeking medical attention for tics since the start of the pandemic—a trend that many of them have linked to TikTok videos, the Wall Street Journal reports. Doctors were reportedly left scratching their heads at the influx of teenage girls experiencing the “physical jerking movements and verbal outbursts,” as men have traditionally been far more likely to develop the movement-disorder. But as doctors in the U.S., Canada, Australia, and the United Kingdom began comparing notes, they realized that all the teens shared a fondness for TikTok videos. They had also reportedly been watching videos of influencers sharing their experience with Tourette’s syndrome, a nervous-system disorder that causes people to make involuntary movements or sounds. Doctors say that the teens who’ve recently experienced such behaviors are likely to have pre-existing diagnoses like depression or anxiety. “There are some kids who watch social media and develop tics and some who don’t have any access to social media and develop tics,” Dr. McGuire, an associate professor at John Hopkins University’s Department of Psychiatry and Behavioral Sciences, was quoted saying. “I think there are a lot of contributing factors, including anxiety, depression, and stress.”