Pandemic-Era Functional Tics Differ Sharply From Tourette Syndrome, Systematic Review Finds

When clinicians around the world began reporting an explosion of sudden-onset, tic-like movements and vocalizations among teenagers during the COVID-19 pandemic, the phenomenon defied easy classification. The patients were overwhelmingly adolescent, frequently female, and often had no childhood history of tics—the hallmark of Tourette syndrome. Many had spent hours watching videos of influencers with tic disorders on TikTok and YouTube, and their own symptoms frequently mirrored those of the creators they followed. A new systematic review published in Frontiers in Child and Adolescent Psychiatry by researchers at Johns Hopkins University School of Medicine and Harvard Medical School now offers the most comprehensive synthesis to date of this condition, known as functional tic-like behaviors, and the picture that emerges is of a disorder that resembles Tourette syndrome on the surface but differs from it in nearly every clinically meaningful dimension.

Functional tic-like behaviors sit at the conceptual intersection of two very different categories of illness. Tourette syndrome and other persistent tic disorders are neurodevelopmental conditions: tics typically begin in childhood, progress in a characteristic head-to-toe, or rostro-caudal, pattern, peak in severity during early adolescence, and affect boys more often than girls, with frequent comorbid attention deficit hyperactivity disorder and obsessive-compulsive disorder. Functional neurological disorders, by contrast, produce neurological symptoms—weakness, abnormal movements, seizure-like episodes—that are inconsistent with identifiable structural or neurochemical pathology and are instead thought to arise from disruptions in functional brain connectivity, network dynamics, and attentional processing. Functional tic-like behaviors borrow features from both worlds, which is precisely why distinguishing them from Tourette syndrome matters: the conditions carry different prognoses and respond to different treatments.

The pandemic was not the first time tic-like symptoms spread through a social network. In 2011 and 2012, a cluster of sudden-onset tics swept through a high school in Le Roy, New York, affecting eighteen adolescents and one young adult; the New York State Department of Health ultimately characterized the outbreak as mass psychogenic illness, with intense media coverage suspected of amplifying symptoms. What changed with COVID-19 was scale and speed. Social media platforms offered a global transmission channel, and a 2024 population-representative German survey estimated the prevalence of social media-induced tic-like illness at between 0.17 and 0.36 percent. In one Australian pediatric clinic, functional tic-like presentations rose from roughly 2 percent of tic cases in 2018 to 36 percent in 2021, and a Boston movement disorder clinic documented an 8.6-fold increase in new functional tic presentations from pre- to post-pandemic periods while developmental tic presentations remained flat.

To organize this fast-moving literature, the Johns Hopkins-led team followed PRISMA systematic review guidelines, searching PubMed and PsycINFO with terms covering tics, Tourette syndrome, and functional neurological presentations. They included English-language studies reporting clinical data on functional tic-like behaviors with at least eight participants, excluding single case reports, non-human work, and commentaries. Thirty-nine studies survived screening, spanning case series, cross-sectional comparisons, case-control designs, and a small number of prospective cohorts. Because many reports drew on the same clinical samples—the Danish national clinic in Herlev, the Hannover and Birmingham specialist services, the University of Calgary tic registry—the authors synthesized findings qualitatively by study sample and conceptual domain rather than pooling numbers, and they appraised methodological quality using the Joanna Briggs Institute critical appraisal tools, with blinded dual-rating of a stratified quarter of the studies showing substantial inter-rater agreement.

Demographically, the syndrome is distinctive. Functional tic-like behaviors begin predominantly in adolescence, with average ages of onset across studies clustering between 13 and 15 years, in contrast to the childhood onset of Tourette syndrome. Clinical registries report female-to-male ratios between roughly 7:1 and 9:1, and gender-diverse individuals are markedly overrepresented, with 37 to 45 percent of participants in several cohorts identifying as gender-diverse—far above population base rates. One report found that gender diversity was more strongly associated with functional tic-like behaviors than biological sex itself. Notably, the German social media-induced illness cohort was an exception, with an even sex distribution that investigators attributed to the male sex of the German YouTube creator proposed as the outbreak’s virtual index case, underscoring how modelled identity can shape who develops symptoms.

Phenomenologically, the review confirms a recognizable profile: abrupt, often explosive onset of complex motor movements and vocalizations that reach peak severity within about a month in most patients, without the rostro-caudal progression typical of Tourette syndrome. The movements themselves range from simple head jerks to directed actions—hitting, throwing, kicking, self-biting—accompanied by socially inappropriate vocalizations, coprolalia, and echoing phenomena. Several features stand out as particularly suggestive of the functional form, including self-injurious behavior, coprophenomena, tic attacks, and symptoms that worsen in the presence of others. The combination of self-injury plus coprophenomena is highly specific to functional tic-like behaviors in several reports, though not diagnostic in isolation. Evidence on premonitory urges and suppressibility is genuinely mixed, with some studies reporting reduced urges and poor suppressibility and others finding the opposite; one direct comparison of Tourette syndrome, functional tic-like behaviors, and comorbid presentations found no differences among the three groups, a finding the authors interpret as reflecting suggestibility and variability in symptom expression.

Psychiatric comorbidity is the rule rather than the exception. An international registry spanning ten centers in eight countries found that up to 80 percent of patients had at least one co-occurring psychiatric condition, with anxiety disorders exceeding 60 percent in most cohorts and mood disorders ranging from 10 to 72 percent. Comorbid Tourette syndrome itself appears in 15 to 50 percent of cases, and other functional neurological symptoms in 16 to 80 percent. By contrast, the classic neurodevelopmental comorbidities of Tourette syndrome—OCD and ADHD—appear at comparatively lower rates in the functional group, and absence of obsessive-compulsive tic-related behaviors and absence of family history of tics were the strongest predictors of a functional diagnosis in one controlled study. Strikingly, after correcting for age and sex, one Danish comparison found psychiatric comorbidity rates did not differ significantly between groups, suggesting the comorbidity profile is shifted rather than simply heavier.

The clinical course is more variable than the onset. A large international registry reported a median symptom duration of twelve months, with spontaneous remission occurring in about 20 percent of patients—though in most of those cases, symptoms later returned. Prospective follow-up studies identified three broad trajectories: global improvement or remission, improvement with persisting impairment, and persistence or worsening with significant disability. Roughly two-thirds of adolescents in a UK tertiary study improved or recovered, but a substantial minority showed no change or deterioration, and about 40 percent of one retrospective cohort developed additional functional neurological symptoms over time, a phenoconversion pattern that raises concern about long-term outcomes. Better prognosis was associated with younger age at onset, shorter time to correct diagnosis, male sex, and discontinuation of secondary gain, while the presence of other functional symptoms and higher baseline severity predicted worse trajectories.

Treatment findings are the most sobering part of the review. Standard Tourette syndrome pharmacotherapy appears largely ineffective: an international registry found that among 122 patients treated with clonidine, guanfacine, aripiprazole, or risperidone, 73 to 89 percent showed no improvement, and any benefit was partial and transient. The Comprehensive Behavioral Intervention for Tics, the frontline behavioral treatment for Tourette syndrome, conferred no advantage over other psychotherapeutic modalities in the one report examining it. More promising signals emerged from treatments targeting the anxiety and mood comorbidities that pervade the condition—cognitive behavioral therapy, serotonin reuptake inhibitors, and psychoeducation all showed retrospective evidence of benefit, and a prospective cohort linked CBT for anxiety or depression to lower tic severity at six months. But only two intervention studies of any kind were identified, both uncontrolled single-arm designs, and neither specified the therapeutic target.

The review’s authors are careful about what their synthesis can and cannot establish. Most of the underlying evidence is retrospective, comorbidity was typically assessed clinically rather than with standardized instruments, no study employed a genuine longitudinal comparative cohort design, and consensus diagnostic criteria remain absent from the field, although the European Society for the Study of Tourette Syndrome’s 2022 criteria showed high retrospective sensitivity in one large series. What the 39 studies collectively establish is that functional tic-like behaviors are a real, distinct, and clinically recognizable entity—not a TikTok fad but a stress-sensitive, socially transmissible functional movement disorder that exploded into visibility during a period of global isolation and now demands randomized trials, validated diagnostic criteria, and mechanistic research. For clinicians, the immediate message is practical: recognizing the profile—adolescent onset, female predominance, abrupt complex symptoms, absent tic history—can shorten time to diagnosis, which is itself one of the few consistent predictors of recovery.

Subject of Research: Demographic, phenomenological, and clinical characterization of functional tic-like behaviors

Article Title: A systematic review to characterize functional tic-like behaviors

Article References: A systematic review to characterize functional tic-like behaviors. (n.d.). https://doi.org/10.3389/frcha.2026.1936806

Image Credits: AI Generated

DOI: 10.3389/frcha.2026.1936806

Keywords: functional tic-like behaviors, Tourette syndrome, functional neurological disorder, COVID-19 pandemic, social media, adolescent mental health, systematic review, tic disorders, psychogenic tics, comorbidity, cognitive behavioral therapy, social contagion