Background
Since the beginning of the COVID‐19 pandemic, our colleagues working at eight different
Tourette syndrome (TS) clinics globally have witnessed a parallel pandemic of young
people aged 12 to 25 years (almost exclusively girls and women) presenting with the
rapid onset of complex motor and vocal tic‐like behaviors.
1
In most cases, these behavioral patterns are consistent with a functional neurological
disorder. There have been striking commonalities in the phenomenology of these tic‐like
behaviors observed across our centers in Canada, the United States, the United Kingdom,
Germany, and Australia. The aim of this viewpoint is to help clinicians recognize
patients with this disorder and distinguish them from patients with TS. We begin by
describing the clinical phenomenology and demographic characteristics of youth with
rapid onset functional tic‐like behaviors (FTLBs) using illustrative data from the
Tic Disorders Clinical Registry at the Calgary Tourette and Pediatric Movement Disorders
Clinic. We then discuss our shared experiences across our eight centers and provide
preliminary viewpoints on the pathophysiology and treatment of this complex disorder.
The Calgary Tic Disorders Clinical Registry
This registry enrolls participants at their first clinic visit into a prospective
cohort study assessing long‐term outcomes in youth with tics. The registry is approved
by the Calgary Health Research Ethics Board, and all participants provide informed
consent. Baseline data elements include age, sex, age at tic onset, current medication
use, tic disorder diagnosis, Yale Global Tic Severity Scale (YGTSS) score, presence
of comorbid attention deficit hyperactivity disorder (ADHD) and symptom severity on
the Conners 3, obsessive‐compulsive disorder and symptom severity on the Children's
Yale Brown Obsessive Compulsive Scale (CYBOCS), anxiety disorder (including generalized
anxiety disorder, social anxiety disorder, or panic disorder) and symptom severity
on the Multidimensional Anxiety Scale for Children version 2 (MASC2), major depressive
disorder and symptom severity on the Child Depression Inventory version 2 (CDI2),
and autism. Possible tic disorder diagnoses recorded in the registry included TS,
persistent motor tic disorder (PMTD), persistent vocal tic disorder (PVTD), and provisional
tic disorder (PTD). The diagnosis of FTLBs was added to the registry in 2020. Using
this registry data, we contrasted clinical features present at the first clinical
visit of participants diagnosed with primary tic disorders and those diagnosed with
FTLBs. Children categorized with primary tic disorders met DSM‐V criteria for TS,
PMTD, PVTD, or PTD. Children categorized with FTLBs had rapid onset of complex tic‐like
behaviors, with escalation to peak severity within hours to days. All diagnoses were
performed by movement disorders specialists with expertise in tic disorders. Continuous
variables were compared between groups using a 2‐sample t test, and categorical variables
were compared using the χ2 test.
Data from 290 registry participants collected between 2012 and June 30, 2021, were
analyzed, comprising 270 with a primary tic disorder (215 TS, 28 PMTD, 4 PVTD, and
23 PTD) and 20 with FTLBs. Of the 20 patients with FTLBs, 17 had no history of previous
tics, whereas 3 had mild simple tics earlier in childhood that were never detected.
Rapid onset of FTLBs occurred in all participants during the pandemic period (after
March 1, 2020), and all endorsed exposure to influencers on social media (mainly TikTok)
with tics or TS. With respect to the phenomenology of tic‐like behaviors, 18 of 20
had complex vocalizations consisting of the repetition of random words or phrases
(eg, knock knock, woo hoo, beans); 11 of 20 engaged in the repetition of curse words,
or obscene, offensive, or derogatory statements; 13 of 20 had complex arm/hand movements
(clapping, pointing, sign language, or throwing objects); and 14 of 20 had complex
behaviors in which they would hit or bang part of their body, other people (typically
parents), or objects.
Table 1 summarizes the demographic and clinical features of registry participants.
Participants with FTLBs were more likely to be female, were older at first visit,
were older at symptom onset, had higher YGTSS total tic and impairment scores, were
more likely to have an anxiety disorder or major depressive disorder diagnosis, and
had significantly higher total symptom scores on the MASC2 and CDI2 (all P < 0.0001).
Logistic regression controlling for age and sex demonstrated a significant association
between the diagnosis of FTLBs and the diagnosis of an anxiety disorder (odds ratio
[OR] 4.42, 95% confidence interval [CI] 1.22, 16.00, P = 0.02) or major depressive
disorder (OR 4.92, 95% CI 1.29, 18.83, P = 0.02). Linear regression controlling for
age and sex demonstrated a significant relationship between the diagnosis of FTLBs
and total tic severity on the YGTSS, with a coefficient of 10.60, 95% CI 5.89, 15.30,
P < 0.0001.
TABLE 1
Calgary tic disorders registry comparison of clinical and demographic features
Variable
Primary tic disorder N = 270
Rapid onset functional tic‐like behaviors N = 20
P‐value
Female sex, proportion
58 (21%)
19 (95%)
<0.0001
Age at first clinical visit (mean and 95% CI)
10.5 y (10.1, 10.9)
14.3 y (13.5, 15.0)
<0.0001
Age at tic onset (mean and 95% CI)
6.4 y (6.1, 6.8)
13.9 y (13.1, 14.7)
<0.0001
YGTSS total tic score
18.4 (17.4, 19.5)
33.3 (28.7, 38.0)
<0.0001
YGTSS impairment score
15.8 (14.2, 17.3)
28.6 (23.1, 34.1)
0.0001
ADHD diagnosis, proportion
120 (44%)
5 (25%)
0.09
Conners 3 Inattention Subscale T score
65.2 (63.3, 67.1)
68.9 (61.1, 76.8)
0.16
Conners 3 Hyperactivity Subscale T score
67.9 (66.0, 69.9)
64.8 (57.3, 72.3)
0.21
OCD diagnosis, proportion
51 (19%)
1 (5%)
0.12
CYBOCS score
5.1 (4.1, 6.1)
2.7 (0.9, 13.1)
0.22
Anxiety disorder diagnosis, proportion
51 (19%)
15 (75%)
<0.0001
MASC2 total T score
57.4 (55.3, 59.5)
71.0 (64.6, 77.4)
<0.0001
Depression diagnosis, proportion
11 (4%)
11 (55%)
<0.0001
CDI2 total T score
58.0 (55.5, 60.4)
74.3 (68.2, 80.5)
<0.0001
Autism diagnosis, proportion
16 (6%)
0 (0%)
0.26
α‐Agonist treatment, proportion
55 (21%)
7 (35%)
0.13
Antipsychotic treatment, proportion
40 (15%)
3 (15%)
0.99
Selective serotonin reuptake inhibitor (SSRI) treatment, proportion
44 (16%)
9 (45%)
0.002
Stimulant treatment, proportion
56 (21%)
3 (15%)
0.53
Calgary Tic Disorders Clinical Registry comparison of clinical and demographic features
of primary tic disorder cases with rapid onset functional tic‐like behaviors.
Abbreviations: CI, confidence interval; YGTSS, Yale Global Tic Severity Scale; ADHD,
attention deficit hyperactivity disorder; OCD, obsessive‐compulsive disorder; CYBOCS,
Children's Yale Brown Obsessive Compulsive Scale; MASC2, Multidimensional Anxiety
Scale for Children version 2; CDI2, Child Depression Inventory version 2.
Viewpoint
Although FTLBs have certainly been described by others in the past,
2
,
3
,
4
until now these cases have represented a small fraction of referrals to TS/tic disorder
clinics.
2
,
3
,
5
Table 2 provides the estimates on the percentage of new referrals for which functional
tics were the primary problem both before the pandemic and in the first half of 2021,
and the average annual number of referrals for tics or movement disorders, across
five of our centers. Although after the pandemic started referral volumes increased
in three centers, remained the same in one center, and decreased in one center, all
centers experienced a dramatic increase in the proportion of referrals for FTLBs.
Although in the past we have managed children with TS with functional tics in addition
to tics related to TS, and observed a small number of functional tic patients each
year as the primary diagnosis, it is the unprecedented increase in new referrals of
young females with the rapid onset of tic‐like behaviors since the pandemic started
that has been so unusual. This has allowed us to record new observations and gather
insights into this specific presentation. Many of these rapid onset patients have
no definite history of previous tics. They experience the rapid onset of complex tic‐like
behaviors that escalate in frequency and severity over a period of hours to days,
prompting emergency department visits and even hospital admission. Their presentation
is notable for complex motor tic‐like behaviors and vocalizations, with a relative
lack of classic simple motor and/or phonic tics and the absence of the expected rostrocaudal
progression at onset,
6
characteristic of primary tic disorders. Common manifestations include large‐amplitude
arm movements, hitting objects, hitting/punching self or family members, clicking,
whistling, repeating a wide range of random and/or bizarre words or phrases, and blurting
out obscenities or offensive statements. In many cases, a premonitory urge before
these tic‐like behaviors is endorsed, as are distractibility and suggestibility. However,
suppressibility of tic‐like behaviors is more limited and variable between individuals.
The magnitude of functional disability and level of parental distress caused by the
tic‐like behaviors are extreme. Family functioning is often dramatically affected
and disrupted. Moreover, many of these young people can no longer attend school or
work due to symptom manifestation but are able to perform some activities of daily
living (eg, utilization of smartphones, computers, creative projects).
TABLE 2
Estimated proportion of referrals for FTLBs and average annual new patient referrals
for tics/movement disorders, pre‐ and post‐COVID‐19 pandemic
Center
Pre‐pandemic: estimated percentage of referrals for FTLBs as the primary problem
January–June 2021: estimated percentage of referrals with FTLBs as the primary problem
Pre‐pandemic: average number of referrals received per year for tics/movement disorders
2020–2021: average number of referrals received per year for tics/movement disorders
Calgary Alberta Children's Hospital Tourette Clinic
1–2
30
186
290
Sydney Children's Hospital at Westmead Tic Clinic
2–5
35
82
116
Tic and Neurodevelopmental Movements (TANDeM) Evelina London Children's Hospital Guy's
and St. Thomas' (GSTT) MD
2
30
300
600
Cincinnati Children's Movement Disorders Clinic
1
20
600
600
UCLA Child OCD, Anxiety and Tic Disorders Program
2
20
92
71
Abbreviations: FTLBs, functional tic‐like behaviors; OCD, obsessive‐compulsive disorder.
The phenomenology of these rapid onset cases represents a noticeable departure from
the usual demographic and natural history of TS (see Table 3). Tic onset in TS typically
occurs between ages 4 and 7 years. Boys are disproportionately affected, by a ratio
of over three to one.
7
Tics typically begin insidiously, with young children usually having a few different
tics at a time that wax and wane and evolve in character. In early years, tics are
mostly simple, for example, eye blinking, nose wrinkling, facial grimacing, sniffing,
throat clearing, or coughing. Complex tics may emerge later, over a period of months
to years, but typically after simple tics have been present for some time. Tics often
worsen in preadolescence (ages 10–12 years) and improve in late adolescence.
8
Other typical characteristics of tic disorders, such as the report of premonitory
sensations or urges to perform tics, subsequent relief of urges after the tic, suggestibility,
and distractibility, can be present in association with both tics (more so in adolescents
than in children
9
,
10
) and FTLBs and may therefore be less useful in differentiating between these two
groups of patients. At difference, an ability to suppress or postpone tics at least
briefly is usually demonstrated in older children with “typical” tics, whereas suppressibility
of FTLBs appears to be less efficient. The associated psychiatric comorbidity pattern
in these rapid onset cases also differs from TS. The most common comorbid disorders
in children diagnosed with TS are ADHD and OCD.
11
In the rapid onset cases, there is a higher representation of anxiety disorders and
major depression.
TABLE 3
Side‐by‐side comparison of phenomenological presentation of tics and rapid onset FTLBs
Typical TS tics
Rapid onset FTLBs
Age of onset
Childhood
Adolescence or early adulthood
Symptom onset
Gradual
Abrupt/acute
Initial type of tic
Simple motor
Complex motor or complex vocal
Sex
Male predominance
Female predominance
Most common tics
Eye blinking
Head movements
Sniffing
Throat clearing
Large‐amplitude arm movements
Self‐injurious movements (eg, hitting self or family members)
Wide range of odd words or phrases
Obscene words or phrases
Most common comorbidities
Attention deficit hyperactivity disorder
Obsessive‐compulsive disorder
Anxiety disorders
Depressive disorders
First‐line treatment approach
CBIT
Exposure and response prevention
α‐Adrenergic agonists
Psychoeducation, cognitive behavioral therapy, CBIT, with particular emphasis on the
functional interventions—identification and management of antecedents and consequences
of FTLBs
Abbreviations: FTLBs, functional tic‐like behaviors; TS, Tourette syndrome; CBIT,
Comprehensive Behavioral Intervention for Tics.
Although most young people with this rapid onset of tic‐like behaviors have not reported
any history of previous tics, we have witnessed several young patients with a history
of mild simple tics who reported an explosive onset of complex tic‐like behaviors
during the same period. Age, sex distribution, phenomenology, and type of onset in
this less‐represented subgroup are similar to the majority of youth with rapid onset
of complex tic‐like behaviors without previous history of tics. This similarity intriguingly
suggests the possibility of shared predisposing factors in these two subgroups. This
presentation differs substantially also from other acute syndromes in which tics or
tic‐like movements are predominant. In particular, we did not notice any association
with recent upper‐respiratory/pharyngeal infections or acute obsessive‐compulsive
spectrum symptoms (eg, those observed in pediatric acute onset neuropsychiatric syndromes),
and the phenomenology was not consistent with acute drug‐induced movement disorders.
Another relevant characteristic of this new clinical presentation is the association
with specific psychosocial stressors, the exposure to which may have increased substantially
during the COVID‐19 pandemic in this age group. A proportion of these patients reported
family‐related emotional distress linked to tensions between parents or other family
members, which may have been exacerbated by the lockdown. Other patients have described
a temporal association between symptom onset and increased stress levels related to
“virtual schooling,” meeting academic expectations, and navigating school–home transitions
that are accompanied by several academic challenges.
What could be at the origin of this specific, explosive presentation of tic‐like behaviors,
and why is it occurring now? Recently, there has been a growth in online video material
of youth manifesting tic disorders, shared on social networks. In some cases, these
videos were pooled under thematic hashtags focused on TS and yielded exponentially
increasing popularity at the beginning of 2021. Interestingly, we and others
1
,
12
,
13
have noticed a phenomenological similarity between the tics or tic‐like behaviors
shown on social media and the tic‐like behaviors of this group of patients. In some
cases, the patients specifically identified an association between these media exposures
and the onset of symptoms, although, with some of the younger children, the social
media use was disclosed only after careful questioning. The COVID‐19 pandemic has
been a major source of stress and anxiety for people globally, resulting in increased
mental health symptoms and demand for mental health services.
14
,
15
,
16
,
17
,
18
Increased social isolation and the widespread utilization of social media may have
contributed as precipitating factors in a relevant proportion of these patients. External
factors like watching popular social media personalities' videos portraying tics or
tic‐like behaviors may have instilled a belief that “tics” may catalyze peer acceptance
or even popularity. This exposure to tics or tic‐like behaviors is a plausible trigger
for the behaviors observed in at least some of these patients, based on a disease
modeling mechanism. However, this specific social media exposure to tic‐related videos,
although reported in all patients in the Calgary series, was not reported in every
patient treated at all the other centers, suggesting that it cannot be considered
a prerequisite or necessary causative factor. There is a need for systematic investigation
of the relationship between symptom onset, severity, and amount of social media exposure.
The explosive behavioral pattern exhibited by these young people could also share
pathophysiological mechanisms with the general population of people with FTLBs, as
proposed in greater detail in Figure 1.
FIG 1
Possible pathophysiological mechanisms for the functional tic‐like behaviors (FTLBs)
exhibited by this group of patients. As recently proposed in the context of FTLBs,
19
a combination of predisposing traits (encompassing, among others, genetic and epigenetic
factors and previous life events), predisposing states (eg, raised anxiety levels
and related low mood), and environmental precipitating factors (increase in media
exposure to tic‐like behaviors, different stressors driven by the pandemic) may prompt
an excess of behavioral alterations, such as recurrent tic‐like behaviors. In specific
groups of people like those whom this viewpoint is focusing on, the environment might
be providing the individual with overabundant external stimuli that may be discerned
as highly salient (ie, attractive and “popular” tics or tic‐like behaviors). Such
behaviors will be selected and reinforced, and the individual will, particularly at
an initial learning stage, allocate an excess of attention to them, thereby enhancing
their probability of recurrence reinforcement. [Color figure can be viewed at wileyonlinelibrary.com]
A comprehensive interview of patients, families, and relevant informants is a first,
necessary step to understand the antecedents and triggering factors involved, which
will allow deeper understanding of this clinical picture and guide personalized management
decisions. Comparisons to historical precedents of similar outbreaks at a more local
level are also useful. For example, a regional outbreak of tic‐like behaviors was
documented in adolescent girls in 2012 in Le Roy, New York, which was attributed to
a combination of conversion disorder and mass psychogenic illness.
19
As our familiarity with this behavioral pattern increases through clinical experience,
we need to explore in depth the psychopathological profile of these patients, as well
as identify recurrent predisposing family‐ and peer‐related stressors. It would also
be relevant to investigate social and adaptive functioning as well as social cognition
domains, particularly the processing of socially salient stimuli, their perception,
and integration of reward mechanisms related to social cues. Finally, a striking characteristic
of this behavioral pattern is its “epidemic” diffusion over a relatively short time,
which differs from the slower pace of referral to specialists' attention of FTLBs
and indicates the involvement of suggestibility and behavioral modeling. In this respect,
it would be useful to explore whether abnormalities in sense of agency and action
monitoring, similar to those observed in people with other functional neurological
disorders, are a consistent trait also in these patients or whether performance on
these domains is more variable.
We wish to bring neurologists' attention to this emerging disorder and highlight the
important phenotypic differences these cases have from typical cases of TS. A prompt
diagnosis and expert review to clarify the phenomenology when necessary is recommended.
We also acknowledge that diagnostic labeling may be difficult when childhood onset
simple tics and the more complex types of rapid onset FTLBs, coexist in the same patient.
20
Our initial, anecdotal experience is that these patients do not respond typically
to conventional pharmacotherapies for tics, either showing dramatic improvement within
hours or days of starting an α‐agonist (suggestive of a placebo response) or having
no response whatsoever to antipsychotic medications with demonstrated high efficacy
for tics.
21
Behavioral treatment approaches, including personalized psychoeducation, seem more
appropriate to initiate a therapeutic process. Intuitively, function‐based therapeutic
strategies,
22
,
23
,
24
including mitigating potential triggering exposures, particularly social media content
associated with tics, initiating stress management interventions related to other
identifiable psychosocial stressors, reducing social reactions to symptom expression,
and addressing comorbid anxiety and depression, could be confirmed as high‐yield strategies
by future observations. Our prediction is that cognitive behavioral therapies, particularly
when including components of the Comprehensive Behavioral Intervention for Tics,
25
might have a considerable chance of success to treat this type of repetitive behavior.
Author Roles
(1) Tamara Pringsheim: conception and design, data acquisition or analysis, drafting,
editing, revising text; (2) Christos Ganos: conception, drafting, editing, revising;
(3) Joseph McGuire: drafting, editing, revising; (4) Tammy Hedderly: drafting, editing,
revising; Doug Woods: drafting, editing, revising; (5) Donald Gilbert: drafting, editing,
revising; (6) John Piacentini: drafting, editing, revising; (7) Russell Dale: drafting,
editing, revising; (8) Davide Martino: conception and design, data acquisition, drafting,
editing, revising.
Full financial disclosure for the previous 12 months
Tamara Pringsheim has received grant funding from the Public Health Agency of Canada
and Alberta Health.
Christos Ganos holds a research grant from the VolkswagenStiftung (Freigeist Fellowship)
and has received honoraria from the Movement Disorder Society for educational activities.
Joseph F. McGuire reports receiving research support from the Tourette Association
of American (TAA), the American Academy of Neurology (AAN), the American Psychological
Foundation (APF), and the Hilda and Davis Preston Foundation. He has served as consultant
to Bracket Global, Syneos Health, and Luminopia and has also received royalties from
Elsevier.
Tammy Hedderly has no financial disclosures.
Douglas Woods has received book royalties from the Oxford University Press, Guilford
Press, and Springer Press and has received speaker's fees from the Tourette Association
of America.
Donald L. Gilbert has received honoraria and/or travel support from the Tourette Association
of America/Centers for Disease Control and Prevention, the Child Neurology Society,
and the American Academy of Neurology. He has received compensation for expert testimony
for the U.S. National Vaccine Injury Compensation Program, through the Department
of Health and Human Services. He has received payment for medical expert opinions
through Advanced Medical/Teladoc. He has served as consultant for Applied Therapeutics
and Eumentics Therapeutics. He has received research support from the NIH (NIMH) and
the DOD. He has received salary compensation through Cincinnati Children's for work
as a clinical trial site investigator from Emalex (clinical trial, Tourette Syndrome)
and EryDel (clinical trial, ataxia telangiectasia). He has received book/publication
royalties from Elsevier, Wolters Kluwer, and the Massachusetts Medical Society.
John Piacentini has no financial disclosures.
Russell C. Dale has National Health and Medical Research Council Investigator fellowship
and Cerebral Palsy Alliance funding.
Davide Martino has no conflicts of interest to report. Davide Martino has received
compensation for consultancies for Sunovion; honoraria from Dystonia Medical Research
Foundation Canada; royalties from Springer‐Verlag; research support from Ipsen Corporate;
and funding grants from Dystonia Medical Research Foundation Canada, Parkinson Canada,
The Owerko Foundation, and the Michael P. Smith Family.