The Challenges of Identifying Tics in Children

ABSTRACT

Tic disorders, including Tourette Syndrome, are prevalent yet frequently overlooked conditions, often leading to delayed diagnoses. Given their substantial overlap with other emotional-behavioral disorders, timely identification is crucial. However, existing screening tools for tics are limited, and research has predominantly been conducted within specialized settings, lacking diversity. To bridge these gaps, we present a collection of studies exploring innovative screening and diagnostic approaches for tic disorders in youth. Screening and early detection may improve access to intervention and secondary prevention, improving outcomes for individuals with tic disorders and their families.

Tics, characterized by sudden, repetitive, involuntary movements or vocalizations, are common, impairing and often persistent. Tics vary from simple blinks, twitches, and grunts to more intricate and at times alarming sequences such as shouting, screaming, self-injury, and involuntary abusive or profane gestures. With a notable male preponderance, tics characteristically fluctuate over time in frequency, topography, and complexity and frequently co-occur alongside other emotional and behavioral disorders. The onset of tics and their peak severity, typically experienced during childhood, pose distinctive social, educational, and physical challenges (Ricketts et al., 2022), highlighting the need for early identification, care planning, and ongoing symptom monitoring. Although evidence-based treatments are available (Murphy et al., 2013), relatively few individuals receive them, in part due to failed recognition and delayed or misdiagnosis. This special issue delves into the critical importance of tic screening and identification, presenting various approaches in both clinical and population settings. It addresses the challenges associated with assessing tics within community samples, among youths with other developmental disorders, and those in underserved urban communities.

Several estimates suggest that tics occur in over 20% of youth (Black et al., 2021; Tinker et al., 2022). Despite their prevalence, tics frequently evade detection or are misdiagnosed, which can lead to significant delays in receiving appropriate care. Tic disorders are typically first identified and diagnosed by specialists, such as neurologists, psychiatrists, or developmental pediatricians, and unfortunately many families consult three or more healthcare providers before receiving a diagnosis (Wolicki et al., 2019). Furthermore, even when tics are identified or suspected, there exists a drastic shortage of specialists and long waiting lists for consultations are commonplace (Majersik et al., 2021) which can delay diagnosis and management, thereby intensifying their adverse effects. Limited access to specialty care, particularly for individuals from groups that have been economically/socially marginalized, compounds these delays, further hindering access to timely diagnosis and treatment (Miller et al., 2014).

It is well established that upwards of 90% of patients with tic disorders will at some point meet criteria for one or more additional neuropsychiatric condition (Hirschtritt et al., 2015), suggesting that the identification of tics may serve as an indicator for the presence of additional emotional and behavioral disorders. Notably, conditions such as Attention Deficit/Hyperactivity Disorder (ADHD), Obsessive-Compulsive Disorder (OCD), and anxiety and mood disorders, commonly co-occur with tics, amplifying the risk for functional impairments (Bitsko et al., 2020; Freeman et al., 2000; Lewin et al., 2010, 2011) and heightening the need for coordinated and specialized healthcare and educational supports (Bitsko et al., 2013; Claussen et al., 2018).

While several tools exist for assessing tic symptom severity (Cohen et al., 2013), options for tic screening and diagnostic tools remain comparatively limited (Martino et al., 2017). Testing of existing instruments has primarily occurred within the confines of small convenience samples, often drawn from specialty settings, with limited representation of youths from diverse backgrounds. Recognizing that primary care providers frequently serve as the initial point of contact for families, integrating tic screening into routine pediatric assessments can facilitate early identification and prompt referral for further evaluation and support. Additionally, while formal diagnosis of tic disorders necessitates clinician expertise, the recognition of potential tic symptoms through brief screenings can prompt the need for clinician follow-up to determine the necessity for diagnosis or specialized assessment. Parents/caregivers, teachers, and youths with tics can contribute to this process, potentially reducing the time to identification and facilitating subsequent screening for common comorbidities. Moreover, there exists an urgent need to explore tic presentations within diverse populations, acknowledging potential variations in symptom manifestation and cultural interpretations. By embracing a culturally sensitive approach to tic screening, clinicians can ensure equitable access to diagnostic resources and tailored interventions for children from all cultural backgrounds.

The imperative of early tic identification, compounded by lengthy waitlists for specialty care, underscores the need for (1) enhancing effective community-based screening and diagnostic tools, (2) broadening initiatives into routine pediatric primary care and educational settings, and (3) enhancing identification efforts in diverse communities including those with limited access to healthcare. This special issue presents a collection of innovative research that bridges the divide between research and clinical care in specialty settings and the community. Collectively, the overarching aim of these studies is to improve early detection, diagnosis, intervention, and support for children grappling with tics and persistent tic disorders, including Tourette syndrome.

Several articles in this special issue discuss the development, testing and refinement of tic screening instruments, which to date have been lacking or of questionable utility. For example, the Motor tic, Obsessions and compulsions, Vocal tic Evaluation Survey (MOVES; Gaffney et al., 1994) has been recommended as a tic screener but is relatively lengthy for a screening instrument (20 self-report items), contains several items that are non-tic specific (e.g. OCD-related questions), and has not been tested as screener or validated outside of an initial validation study (Gaffney et al., 1994). To address these shortcomings, researchers from the University of South Florida, the University of Rochester, and the Centers for Disease Control and Prevention (CDC) evaluated how well six of the tic-related items from MOVES differentiated between youth with a persistent tic disorder and a sample of controls. They found that both the 20-item and an abbreviated 6-item version of the MOVES had high sensitivity and specificity compared to expert clinician assessment. These findings suggest that a 6-item subset of the MOVES is a potentially effective screening instrument for tics. The paper presents an empirically informed cutoff score to reliably differentiate youth with tics from controls (Lewin, Murphy, et al., 2024).

Expanding upon this research, Smith et al. (2024) administered the same 6-item version of the MOVES (see Lewin, Murphy, et al., 2024) to a large sample of youth in middle and high school. This epidemiological approach allowed for a non-clinic-based evaluation of the impact of tics on academic and social impairment. Using the cutoff suggested in Lewin, Murphy, et al. (2024), the MOVES screener identified 257 of 2312 youth (11.1%) to have tics. The authors found that, above and beyond both externalizing and internalizing emotional-behavioral problems, the presence of potential tics identified by the 6-item MOVES contributed unique variance in both social and school-related impairment; youth with potential tics and both internalizing and externalizing problems had greater academic-related impairment. The authors also examined youth-teacher agreement on the MOVES and found generally poor agreement (in cases of disagreement, it was more common for youth to report the presence of tics).

To further improve upon existing screening instruments for tics, Lewin, Brennan, et al. (2024) developed the Motor or Vocal Inventory of Tics (MOVeIT). The special issue includes their research outlining item development, preliminary testing, and a pilot evaluation conducted within the context of both a specialty neuropsychiatric clinic and Tourette Association of America Tourette Center of Excellence (the University of South Florida Rothman Center). The study found that a 14-item version of the MOVeIT screener had strong sensitivity and acceptable specificity, accurately classifying 83% of cases with strong parent–child agreement. Although the authors acknowledged that there were false positives (11.5%), they highlight the fact that the MOVeIT was developed as a screening tool with an emphasis on minimizing false negatives given that tics often go undetected.

Building upon this work, Adams et al. (2024) at the Tourette Association of America designated Center of Excellence at the University of Rochester, in cooperation with the CDC, examined the performance of parent, youth and teacher versions of the MOVeIT alongside a brief diagnostic assessment for tics called the Description of Tic Symptoms (DoTS). The aim was to examine performance of each of these tools to correctly classify a clinical sample of youth with tics (established by expert clinician diagnosis) compared to a community sample. The study found that both the parent and youth versions of the MOVeIT accurately separated cases of tics from controls. In contrast, the teacher report had lower sensitivity but maintained high specificity, suggesting screening for tics in a single setting or from a single informant might not be ideal. Encouragingly, the brief diagnostic rating (DoTS) showed 100% sensitivity; however, the authors highlight the need to validate the DoTS in a community setting, given that their study examined the DoTS’ ability to separate youth with known tics from controls.

Also focusing on diagnostic instruments, Bitsko et al. (2024) found strong convergence between the Diagnostic Interview Schedule for Children for DSM-5 (DISC-5) and expert diagnosis. This is encouraging given that the DISC is a commonly used assessment tool, but prior research suggested that the previous version of the DISC (the DISC-IV) showed low sensitivity to both parent and youth reports on the tic module (Lewin et al., 2014). Using the same sample described in Adams et al. (2024), the current study found that the parent DISC-5 tic disorder module correctly identified tic disorders with over 90% accuracy and sensitivity/specificity. In contrast, youth report had 81.4% accuracy but only 69.8% sensitivity, suggesting youth may underreport tic symptoms on the DISC-5. Nevertheless, the DISC-5 appears to be improved over the previous version, especially with the accuracy of parent report, but testing in non-specialty settings is needed prior to widespread use.

Vermilion et al. (2024) and colleagues further extended the aforementioned line of tic-screening research by examining the use of the MOVeIT in a sample of children from a developmental pediatric clinic. The aim of the study was to evaluate the performance of the tic screener in a sample with overlapping tics and stereotypic movements, which can be particularly challenging to differentiate. Overall, the MOVeIT showed good sensitivity, but specificity was low, especially for youth with co-occurring tics and stereotypic movements. Specificity improved dramatically when youth with stereotypies were excluded. Although the screener seemed unlikely to miss cases of potential tics, the ability to accurately identify tics in this sample of youth with neurodevelopmental and behavioral disorders was limited by a high rate of false positives. A 10-item version of the MOVeIT performed similarly to the 14-item version and was recommended for future use due to its brevity.

In a highly innovative study using machine learning, Wardrop and team (2024) at the University of South Carolina utilized random forest models and logistic regression to identify items from both the MOVeIT and DoTS that best predicted the presence of tics. Combining data from 1205 youth from several studies, the authors found that random forest plots (which result in reduced false negatives) outperformed logistic regressions and identified optimal items for differentiating cases of tics based on both analytical approaches, which can be used to improve both tools prior to further testing.

To date, research on the occurrence of tic disorders in historically marginalized communities is extremely limited. In the final study of the special issue, Striley et al. (2024) present an innovative approach utilizing a video-based screening instrument to assess 154 participants, primarily adults, within a diverse urban community in St. Louis. Notably, 129 (85%) participants identified as Black. The investigators evaluated the acceptability of the screening approach and the feasibility of door-to-door community screening to address access gaps, potentially contributing to our understanding of the variable rates of tic prevalence based on race and ethnicity in an underserved community. Employing the Video-Integrated Screening Instrument for Tics and Tourette Syndrome (VISIT-TS), participants were shown videos of tics followed by a 16-item interview assessing tic symptom lifetime prevalence and chronicity. Screening results suggested rates of Tourette Syndrome consistent with those reported in other prevalence studies. However, one of the most innovative aspects of this research lies in its community-based methodology for screening tic disorders in historically marginalized communities. Furthermore, the paper offers a comprehensive review of the state-of-the-literature concerning tic prevalence/identification based on biology, culture, race, and ethnicity. This study did not include a validation of the screener or expert assessment of tics; with 64% female participants, reports of any tic lifetime history may be an underestimate.

In summary, this special issue presents a collection of interrelated studies aimed at advancing the literature on effective practices for tic screening, validating diagnostic tools, and exploring different methodological approaches for assessing for the presence of tics across diverse clinical, community, and population settings. Employing innovative approaches ranging from machine learning techniques to community public health, these investigations suggest preliminary performance and suggestions for modifications for future study in larger, community samples (Mårland et al., 2017). Additionally, a novel community-based door-to-door video-assisted screening strategy is outlined, offering insights into addressing disparities in screening accessibility. While the focus remains on tics, the findings have wide ranging implications given their widespread prevalence – estimated at 20–25% or higher. Given that approximately 90% of individuals with tics also manifest co-occurring emotional and behavioral disorders, enhancing tic identification, particularly considering their typical onset in early childhood, holds promise for early intervention and prevention of subsequent mood, anxiety, learning, and inhibitory disorders, thereby mitigating future morbidity. This series of research advances our understanding of the available tools for tic screening, including their limitations, with several suggestions for iterations. Even if tools performed well in specialty populations or in comparison to recruited controls, future studies need to examine their performance in general population settings before widespread use can be fully supported.

Disclosure statement

The authors received an editorial honorarium from the Society for Clinical Child and Adolescent Psychology.