Publisher Health

CALGARY, Alberta — Aidan’s tics erupted one day after school in early 2021, about a month after the long pandemic lockdown had ended. The 16-year-old convulsed while walking into the house, head snapping and arms swinging, sometimes letting out high-pitched whistles and whoops.

Aidan’s parents looked up from the living room couch with alarm. They had been worried about the teenager’s ratcheting anxiety — related to Covid, gender dysphoria, college applications, even hanging out with friends. But they were not prepared for this dramatic display.

“We watched this happen in front of our eyes,” Aidan’s mother, Rhonda, recently recalled. “It looked like Aidan was going crazy.”

They rushed Aidan to the emergency room, but doctors found nothing wrong. After calling a neurologist, the family learned that more than a dozen adolescents in Calgary had recently come down with similar spasms.

Over the next year, doctors across the world treated thousands of young people for sudden, explosive tics. Many of the patients had watched popular TikTok videos of teenagers claiming to have Tourette’s syndrome. A spate of alarming headlines about “TikTok tics” followed.

But similar outbreaks have happened for centuries. Mysterious symptoms can spread rapidly in a close-knit community, especially one that has endured a shared stress. The TikTok tics are one of the largest modern examples of this phenomenon. They arrived at a unique moment in history, when a once-in-a-century pandemic spurred pervasive anxiety and isolation, and social media was at times the only way to connect and commiserate.

Now, experts are trying to tease apart the many possible factors — internal and external — that made these teenagers so sensitive to what they watched online.

Four out of five of the adolescents were diagnosed with a psychiatric disorder, and one-third reported past traumatic experiences, according to a study from the University of Calgary that analyzed nearly 300 cases from eight countries. In new research that has not yet been published, the Canadian team has also found a link to gender: The adolescents were overwhelmingly girls, or were transgender or nonbinary — though no one knows why.

Perhaps as striking as the wave of TikTok tics is how quickly it has receded. As teenagers have resumed their prepandemic social lives, new cases of the tics have petered out. And doctors said that most of their tic patients had now recovered, illustrating the expansive potential for adolescent resilience.

“Adolescence is a period of rapid social and emotional development,” said Dr. Tamara Pringsheim, a neurologist who co-led the studies in Calgary. “They are like sponges, grabbing onto new skills to cope.”

Curious Clusters

Historians looking back thousands of years have come across stories of patients — most often women — with tremors, seizures, paralysis and even blindness that could not be explained. The ancient Greeks called it “hysteria” and blamed a wandering uterus. Sigmund Freud deemed the condition “conversion” and theorized that it was caused by suppressed traumatic experiences.

In more recent decades, scientists have gained a greater understanding of how anxiety, trauma and social stress can spur the brain to produce very real physical symptoms, even if body scans or blood tests show no trace of them. When these illnesses interfere with day-to-day life, they are now called “functional disorders.”

“We all recognize that the mind can make the body do things,” said Dr. Isobel Hayman, a child and adolescent psychiatrist at the UCL Great Ormond Street Institute of Child Health in London, who published the first report on the pandemic tics. Most people, after all, have experienced fear that makes their heart race or anxiety that ties their stomach in knots.

“But when the symptoms are quite bizarre and quite intense — like a seizure, or not being able to walk, or ticlike movements — we think, ‘How on earth can the brain generate symptoms like this?’” Dr. Hayman said. “It just can.”

These sudden symptoms can also spread in clusters, reflecting the shared pressures on a group. In the Middle Ages, a period when many Europeans feared being possessed by the devil, nuns living in a French convent began meowing like cats. In the 2000s, hundreds of children of asylum seekers in Sweden became mute and bedridden for months to years.

But ask any neurologist about the TikTok tics and they will bring up Le Roy, a small town in western New York. In 2011, a cheerleader at the local high school erupted in a fit of spasms. A few weeks later, her best friend began snapping her head. The tics spread quickly through the social hierarchy at the school, affecting 18 girls, one boy and one adult woman.

The national news media speculated about toxins or viruses contaminating Le Roy. But neurologists treating the girls knew that many had experienced trauma or serious illnesses in the family.

“These kids all had their own little albatross that they carried,” said Dr. Jennifer McVige, a neurologist at the Dent Neurologic Institute in Amherst, N.Y., who treated many of Le Roy’s teenagers and has also treated adolescents with the TikTok tics.

Although so-called mass psychogenic illness has occurred throughout history, social media has dissolved the boundaries that once kept it geographically contained.

“In the past, most episodes were limited to a specific location, such as a classroom,” said Robert Bartholomew, a historian who has documented 3,500 such outbreaks since the Middle Ages. “But now that’s no longer true.”

The Pandemic Crash

Aidan had always been a sensitive child. At 6, during a turbulent period for the family when their mother was ill, Aidan began to occasionally tic, clearing their throat or rolling their eyes. (The family asked to be identified by their first names because of privacy concerns.)

Aidan was raised as a boy. By adolescence they gravitated toward friendships with girls, came out as bisexual and traded sports for ballet and theater. Sometimes they were severely bullied. Once, Aidan’s skull cracked after they were dragged by the ankles into a shower in the boys’ locker room.

In high school, Aidan came out as nonbinary and began using “they” and “them” pronouns. They grew out their hair and occasionally wore skirts to school, trying to figure out what felt right. Their parents, while supportive, were worried about the changes, making Aidan feel angry and unsettled.

The teenager took refuge in drama class, where being different was encouraged. But in retrospect, Aidan realized that the group glamorized mental illness, sometimes flaunting psychiatric diagnoses.

“It was like a weird fetishization of sadness,” said Aidan, now 18.

When the Covid lockdown was announced, Aidan felt a tinge of relief. Online school allowed the teenager to fly under the radar, drawing or watching videos on their phone.

On TikTok, they found scores of teens who were sharing their experiences with all kinds of health issues, including multiple personality disorder and Tourette’s. Aidan was especially moved by videos of Billie Eilish, the young pop star who in 2018 revealed she had Tourette’s, that were edited together to show her tics. Aidan felt an intoxicating connection to these strangers whose suffering was plain to see.

But when school reopened in January of 2021, their stresses came flooding back. Aidan found the noise at school overwhelming and was often too anxious to eat.

Seated in class one frigid afternoon weeks later, the teenager sent their parents a long text message with an urgent request.

“I think I should see a therapist,” Aidan wrote. They had started having panic attacks, they said, sometimes pulling at their skin while struggling to breathe. Their social interests were narrowing as they spent more and more time on their phone.

“I want an answer,” the teenager wrote. “I just wanna know if I have an illness.”

Aidan started therapy soon after. But within a month, they were convulsing in the living room.

The Tic Influencers

Around the time Aidan started to tic, Dr. Pringsheim and Dr. Davide Martino, movement specialists at the University of Calgary, saw a message in an online forum for the American Academy of Neurology.

“My practice has seen an unprecedented increase in young adolescent women with what appears to be acute explosive motor and vocal tics,” wrote a doctor in Kansas City, Mo.

The Canadian neurologists had seen the same thing. Most of these new patients did not fit the mold of a typical case of Tourette’s, which generally affects boys and begins in early childhood. Tourette’s tics tend to be simple movements — like blinking or coughing — and they wax and wane over time. In contrast, the new patients were often rushed to the emergency room with tics that had appeared seemingly overnight. They were relentless, elaborate movements, often accompanied by emotionally charged insults or funny phrases.

The matching accounts from physicians across the world made the neurologists suspect a shared source. They searched on YouTube but found little. Dr. Pringsheim’s teenage daughter suggested that they look at TikTok, an app used by more than two-thirds of American teenagers.

When they searched for the word “tic” and hundreds of videos popped up, Dr. Pringsheim was stunned.

“This is the person that I saw in my clinic today,” she recalled thinking.

The TikTok influencers were saying the same words — like “beans” and “beetroot” — and making the same motions, like thumping their fists on their chests.

Over the next few months, the influx of patients made the pediatric movement disorder clinic’s waiting list swell from three months to a year. “It was an avalanche,” Dr. Pringsheim said.

TikTok videos labeled #Tourettes have been viewed 7.7 billion times.

Letting Go

In the months after the frightening trip to the E.R., Rhonda contacted dozens of pediatricians, neurologists and psychiatrists. Aidan started on a variety of psychiatric medications — including antipsychotics — but the drugs came with side effects and seemed to make the tics worse.

In August 2021, after missing six months of school, Aidan was offered a coveted spot at a small rehabilitation clinic for functional disorders at Alberta Children’s Hospital. Aidan was constantly lurching, hitting themselves and shouting obscenities. “I hate you,” they often yelled at their mother. “Pay me!” “Beetroot!” “I’m a silly goose!”

At the heart of the rehabilitation program, based on years of experience with functional disorders, was a cognitive-behavioral approach that addressed the psychological root of the problem and helped children develop better ways to cope.

The patients needed to accept two things: that they did not have Tourette’s, and that their twitches were partly under their control. They had to want to get better.

For eight to 10 hours a week for six months, Aidan met with a variety of specialists, including a speech therapist, a dietitian and a psychiatrist. In therapy, the teenager discussed getting bullied at school, their growing stress over their gender and how isolated they had become during the pandemic. They deleted TikTok and started on antidepressants.

In group therapy with other parents, Rhonda and Norm were encouraged to draw their focus away from their teenager’s symptoms.

“It was giving parents permission not to respond,” said Dr. Rachel Hnatowich, a psychiatrist at Alberta Children’s Hospital who helped treat Aidan. Doing so, she said, would help take away the “meaning and power” of the illness.

Initially, many of the teenagers seemed hesitant to let go of their tics, Dr. Hnatowich said. Their behavior had some upsides, often allowing them to get more attention from distracted parents or to avoid the social and academic stresses of school.

The program encouraged the teenagers to slowly re-engage with the real world.

“Doing anything is better than doing nothing,” Dr. Hnatowich said. “Your best interest is to get back to your life and do the things that give you meaning.”

Gender Overlaps

By last summer, Dr. Martino and Dr. Pringsheim had compiled a detailed registry of 294 tic cases from clinics in Australia, Britain, Canada, France, Germany, Hungary, Italy and the United States. They wanted to know: What made these adolescents so vulnerable to the tic videos, while others scrolled past?

An overwhelming number of patients had a history of mental health conditions. Two-thirds were diagnosed with anxiety and one-quarter had depression. One-quarter had autism or attention deficit hyperactivity disorder. Roughly one in five had a prior history of tics.

Eighty-seven percent of the patients were female, a sex skew that was also found in previous outbreaks of mass psychogenic illness. No one knows why girls are more susceptible to this kind of social influence. One theory is that women may seek out belonging more than men do, and may empathize more strongly with others’ suffering. Women also experience higher rates of depression, anxiety and sexual trauma than men.

At a conference on tic disorders last summer in Lausanne, Switzerland, doctors from several countries shared another observation: A surprising percentage of their patients with the TikTok tics identified as transgender or nonbinary. But without hard data in hand, multiple attendees said, the doctors worried about publicly linking transgender identity and mental illness.

“These kids have a tough enough life already, and we don’t want to inadvertently somehow make things even worse for them,” said Dr. Donald Gilbert, a neurologist at Cincinnati Children’s Hospital, whose adult daughter is transgender.

This April, the Calgary group plans to present the first analysis of the gender data at a neurology meeting in Boston. Looking at a sample of 35 patients with the TikTok tics, the researchers found that 15 of the adolescents — 43 percent — were transgender or nonbinary, compared with 12 percent of their patients with Tourette’s or with no tics. (An estimated 1.4 percent of the general population of adolescents in the United States identify as transgender.)

Other neurologists told The New York Times that they had also seen a disproportionate number of gender-diverse adolescents with the sudden tics. At a London clinic, about 11 percent of patients were transgender or nonbinary. The head of a large clinic in Paris said 12 percent were gender diverse. At a clinic in Hanover in Germany — the only country where many boys developed the sudden tics, probably because of the popularity of a young male influencer with Tourette’s there — the figure was 6 percent.

Dr. McVige, the neurologist who treated the girls in Le Roy, said that four out of her seven patients with TikTok tics were transgender, nonbinary or had gender dysphoria. Dr. Gilbert estimated that among his 200 patients in Ohio, 25 to 30 percent were transgender or nonbinary.

“We haven’t made any conclusions about this,” Dr. Pringsheim said. “But we know that there’s something going on here.”

Though the data is limited, some studies have suggested that transgender people have higher rates of functional disorders, which may be related to experiencing higher rates of discrimination, stigma and bias, said Dr. Z Paige L’Erario, a neurologist in New York City who collaborated on the unpublished study.

These adolescents were “at an already difficult time of their life, going through this pandemic,” said Dr. L’Erario, who is nonbinary. The tics were “a manifestation of their hardship.”

Other doctors suspect that a small subset of adolescents with serious mental health issues may be more susceptible to social influences. And during the pandemic, adolescents spent more time online, engaging with increasingly popular content related to mental health and gender, Dr. Hnatowich said.

“These are kids that are open to seeing themselves as very fluid and trying to figure themselves out,” she said. “There is a lot of, ‘Who am I?’”

New Milestones

Shortly after finishing the rehab program, Aidan returned to school. They wrote and directed their first play, and graduated on time, with honors.

Aidan hasn’t had a tic in a year. They no longer use TikTok — not because they’re afraid of getting sick, but because they find it boring. They still go on Instagram.

Aidan has learned to better identify and manage their anxiety. With the support of their psychiatrist, the teenager is planning to wean themselves off antidepressants early next year. Their stress about gender has also faded. They now believe that the tics were an unfortunate byproduct of an earnest, if futile search for definitive answers about their mental health and identity.

“After a year of therapy, I came to the conclusion that labels are stupid,” Aidan said. “I’m just out here.”

Neurologists said that a majority of the adolescents who developed tics during the pandemic — even those who did not have intensive treatment like Aidan — have stopped twitching. Those who did not get better have often refused to accept the functional diagnosis. Others have struggled to resolve the stressors underlying the tics. Some have developed other symptoms, like seizures or paralysis.

Though Aidan’s illness derailed their lives for a year, Norm, Rhonda and Aidan said the experience pushed them to grapple with painful family dynamics that long predated the pandemic. “We’re closer than we were before,” Rhonda said.

In the fall, Aidan enrolled at the University of Calgary, where they are studying art. Last week, they started a part-time office job. They take the bus to class, for now. “I’m hoping to get my driver’s license,” they said, grinning.