Tic disorder (TD) is a childhood-onset neurodevelopmental condition defined by involuntary, sudden, uncontrollable, and repetitive muscle movements or vocalizations. Tourette syndrome (TS) is diagnosed when both motor and vocal tics are present. TD/TS are movement disorders of neurobiological origin, often associated with or exacerbated by psychobehavioral problems [1]. The estimated lifetime prevalence of TD is 0.1% to 1%, with onset typically between ages 5 and 6 years [2,3]. Symptoms usually first appear in the head and neck and may later involve muscles of the torso, arms, and legs. TD/TS occurs more frequently in boys than in girls, and motor tics generally precede vocal tics [4,5]. Common simple motor tics include eye blinking, neck jerking, shoulder shrugging, and facial grimacing, while simple vocal tics often consist of throat clearing, barking, sniffing, and hissing [5,6]. Symptoms usually peak between ages 10 and 12 years. Approximately one-half to two-thirds of cases improve significantly by late adolescence or early adulthood, though in some individuals, TD/TS may persist or even worsen in adulthood [4,7].

TD/TS shares clinical and genetic features with obsessive-compulsive disorder (OCD). Neurophysiological and neuroimaging studies have identified abnormalities in networks involving the frontal cortex, supplementary motor area, premotor areas, striatum, globus pallidus, and thalamus [8-10]. Pathological changes in the cortico-striatal-thalamo-cortical (CSTC) circuit are implicated, with dopamine dysfunction considered a primary factor [11,12]. Dysregulation of CSTC circuits, which govern motor, emotional, and adaptive functions, along with abnormalities in dopamine and serotonin pathways, is believed to underlie both TD/TS and its comorbidities [13-15].

Treatment of tics typically begins with education and supportive measures. Behavioral interventions such as habit reversal training and the comprehensive behavioral Interventions for Tics are used as non-pharmacological approaches. Pharmacological treatment is usually reserved for more severe cases, with dopamine D2 receptor antagonists being the most effective for tic suppression. Typical neuroleptics such as haloperidol and pimozide have proven effective, while atypical antipsychotics like aripiprazole are increasingly favored for their more favorable side effect profiles [15-18].

Children with TD/TS have a higher prevalence of comorbid neuropsychiatric and behavioral disorders than the general population, including attention-deficit/hyperactivity disorder (ADHD), OCD, emotional dysregulation, and disinhibited speech or behavior [6,8]. These vulnerabilities may increase susceptibility to bullying, which in turn can lead to school refusal, social withdrawal, and long-term developmental impacts.

Severe tics can impair both social and academic functioning, and the presence of comorbid conditions may further complicate treatment and prognosis. Thus, it is essential to evaluate coexisting neuropsychiatric issues at the time of initial diagnosis and throughout follow-up [17,18]. Early identification may reduce negative educational and social outcomes and improve long-term prognosis.

Although TD/TS is a clinically significant neurodevelopmental disorder, research on the comprehensive neurocognitive and behavioral profiles of affected children remains limited. While several studies report that children with TD generally have normal intelligence, they often show lower Processing Speed Index (PSI) scores than healthy controls (HC) [19-21] and display a range of behavioral problems on standardized assessments [22]. In addition, studies using the Korean Child Behavior Checklist (K-CBCL) have shown significantly higher mean T-scores for attention problems, anxiety/depression, withdrawal, and emotional lability in children with TD/TS compared with controls [20].

Despite these findings, relatively few studies have simultaneously examined both cognitive and behavioral characteristics in children with TD. To better support affected children, especially those experiencing subtle difficulties in social adaptation, a more comprehensive understanding of their neurobehavioral profiles is needed [23].

The aim of this study was to evaluate the neurocognitive and behavioral characteristics of children with TD/TS and to identify specific associated traits. We hypothesized that children with TD/TS would differ significantly from HCs in both cognitive functioning and behavioral problems. While current management often includes reassurance, behavioral therapy, or medication, delayed recognition of coexisting psychological and behavioral issues may result in untreated problems persisting into late adolescence.

In the present study, we comprehensively examined the neurocognitive and behavioral profiles of children with TD/TS, comparing them with HC. To minimize bias from coexisting conditions, we included only participants with normal-range IQs and excluded those with serious neurological or physical disorders. The TD/TS group demonstrated significantly lower non-VIQ, behavioral functioning, executive function, and attention scores compared with the HC group, highlighting distinct differences between groups.

Within-group analysis showed that the mean FSIQ in the TD/TS group fell within the normal range (98.8±11.7), with VCI scores generally higher than nonverbal indices (POI, PRI, VSI) and psychomotor speed (PSI). Because different Wechsler test editions were administered across years, we referenced only mean scores rather than performing direct statistical comparisons. Comparisons with controls were conducted solely using the K-WISC-IV, revealing that the TD/TS group had significantly lower nonverbal reasoning (PRI) scores than HC (97.5±9.4 vs. 106.3±10.4, P=0.010).

These findings partially align with previous studies. For example, Wanderer et al. [19] observed higher VCI and lower PSI scores in children with only chronic TD or only OCD compared with German standardization data, although the results did not reach statistical significance. Debes et al. [21] found that HC had higher PIQ and FSIQ scores than matched TS participants, while the TS group showed higher VIQ scores on the WISC-III. Conversely, Rizzo et al. [29] reported no significant FSIQ differences between TS-only and control groups.

In the present study, FSIQ did not differ significantly between TD/TS and HC groups. However, PRI scores were notably lower in the TD/TS group. The PRI measures nonverbal reasoning and categorization abilities based on accurate and rapid performance of visually presented tasks, and performance is influenced by visuomotor coordination. Reduced PRI scores suggest that children with TD/TS may have weaknesses in visuospatial reasoning and fine motor skills, with decreased speed and accuracy on tasks requiring these abilities.

Although the proportion of individuals exceeding the ADHD cutoff on the K-ARS-IV did not significantly differ between TD/TS and HC groups, mean K-ARS-IV scores were significantly higher in the TD/TS group. Relative deficits in attention and impulse control, as well as increased error rates, may have negatively influenced PRI performance.

Notably, lower PRI scores may also reflect intrinsic neurocognitive characteristics of TD/TS, including difficulties with visuospatial processing, attentional regulation, and nonverbal problem-solving. Further research with larger samples and detailed psychiatric evaluations will be necessary to better characterize these features.

The CBCL assesses a wide range of behavioral and adaptive problems in children. In this study, the proportion of participants within borderline and clinical ranges for internalizing problems, externalizing problems, total problems, anxious/depressed problems, somatic complaints, thought problems, anxiety problems, somatic problems, ADHD, obsessive-compulsive problems, and stress problems on the CBCL 6-18 was significantly higher in the TD/TS group than in the HC group. A prior study by Cui et al. [22] demonstrated positive correlations between functional impairments (subscales of the Yale Global Tic Severity Scale) and both thought problems and rule-breaking behavior, suggesting that behavioral and emotional difficulties may exacerbate the functional impairment associated with TS. The CBCL thought problems scale evaluates behaviors reflecting difficulties in cognitive processing, often linked to disorganized or irrational thinking, preoccupations, or unusual thoughts. Items may include obsessive thoughts, compulsions, unusual ideas or behaviors, self-harm, hallucinations, nervous twitching, excessive body-picking, inappropriate sexual behaviors in public, compulsive hoarding, sleepwalking or sleep-talking, and sleep disturbances. The scale is especially relevant for identifying children at risk for more serious psychiatric conditions, such as obsessions, autistic features, and psychosis [30,31]. Many individuals with tics, particularly older children, become aware of premonitory urges—feelings of tightness, tension, or itching associated with discomfort or anxiety—that are relieved only by performing a tic. As awareness of these urges increases, patients with TS may exert partial voluntary control over their tics. However, resisting the mounting tension of premonitory urges often results in mental and physical exhaustion, which can be more impairing and distracting than the tics themselves [32]. In this study, the TD/TS group exhibited higher CBCL scores across multiple domains compared with healthy children. It is plausible that the cognitive and emotional burden of suppressing tics manifests as behavioral and emotional problems. Because such problems may also be influenced by comorbid conditions like ADHD or OCD, future research with larger samples and subgroup analyses is warranted.

The CCTT and STROOP tests evaluate different aspects of executive function. Executive function refers to a set of cognitive processes that enable behavioral regulation through cognitive control [26,27]. Selecting and maintaining attention on relevant behaviors is critical for achieving goals, and deficits in these processes are commonly reported in children with ADHD. Both tests are validated measures of executive function in pediatric populations. In this study, the CCTT did not reveal significant group differences. However, on the STROOP test, the TD/TS group demonstrated a significantly lower T-score for color naming and a higher interference T-score compared with the HC group. The interference score reflects the performance difference between the color-word naming and word reading tasks. It measures cognitive flexibility and selective attention by evaluating a child’s ability to name the ink color of a word, despite the word itself representing a conflicting color. A higher interference score indicates greater difficulty in managing cognitive conflict and suggests impairments in cognitive control, attentional regulation, and suppression of automatic reading responses [29]. Although prior research findings have been inconsistent, several studies suggest that executive dysfunction in TS is specifically associated with reduced inhibitory control and impaired cognitive flexibility [33,34]. The present results also indicate challenges in cognitive flexibility and selective attention among children with TD/TS, implying that they may experience difficulty suppressing automatic responses and maintaining cognitive control [35].

A total of 17.1% (n=6) of the TD/TS group scored above the cutoff for ADHD on the K-ARS (≥19). Previous studies have reported that 50%-60% of children with tics present with comorbid ADHD. For example, Rizzo et al. [7] found that children in the TS+ADHD subgroup exhibited more behavioral problems and poorer quality of life across all subscales compared with the TS-only group and HC [36]. Similarly, Roessner et al. [37] reported that ADHD was associated with deficits in neuropsychological performance, particularly in comorbid TD+ADHD cases [38]. The present findings also confirmed that approximately 17% of the TD/TS group had clinically diagnosed ADHD. Attention problems in these children may be related not only to comorbidity but also to the distracting effects of motor and vocal tics, as well as the mental effort required to suppress tics. As demonstrated in previous research, comorbid ADHD can exacerbate cognitive dysfunction, underscoring the importance of timely diagnosis and management of ADHD in children with TD/TS to support optimal cognitive development [38].

This study has some limitations. The sample size of both the TD/TS and HC groups was relatively small, warranting confirmation in larger cohorts. Selection bias may also have influenced the results, as neurocognitive and behavioral assessments are more likely to be performed in children with more severe TD/TS symptoms or clinical concerns about cognitive or emotional functioning.

In summary, children with TD/TS showed no significant differences in FSIQ compared with HC but exhibited relative weaknesses in the PRI and difficulties in executive functioning, particularly in tasks requiring attention and cognitive flexibility. Behavioral assessments revealed a higher prevalence of behavioral and emotional problems, and approximately 17% of children with TD/TS were diagnosed with comorbid ADHD.

In conclusion, clinicians caring for pediatric patients with TD/TS should be attentive to comorbid conditions such as ADHD, behavioral problems, and emotional difficulties, and should recognize patterns of strengths and weaknesses on WISC performance. Intellectual ability plays an important role in cognitive functioning, social adaptation, and school achievement. A thorough understanding of the neurocognitive and behavioral characteristics of children with TD/TS can inform the development of tailored interventions and contribute to improved treatment outcomes and social adjustment.

Although cognitive weaknesses or behavioral problems may not be immediately apparent at diagnosis, routine incorporation of cognitive and behavioral assessments into the diagnostic and treatment process is recommended for children with TD/TS.