## 3 Results
### Studies Characteristics
#### 3.2.3 Classification of Interventions  
Treatment programs have been examined to identify theoretical foundations, objectives, modalities, and validity. As previously highlighted, studies were highly heterogeneous in the treatments models and modalities (see Table A3), with overall durations ranging from a minimum of three weeks [29] to a maximum of ten weeks [15; 19; 21; 22]. The majority of the studies implemented protocols of eight to ten sessions [15; 18; 19; 21; 22; 231], with each session generally lasting 60-90 min [15; 19; 30; 31]. Interventions were administered by therapists with varying levels of experience, from recent graduates [20; 21; 30] to clinicians with extensive practice experience [15; 18; 19; 22; 29; 31]. Notably, all interventions had a behavioral approach [4]. Furthermore, the Comprehensive Behavioral Intervention for Tics (CBIT) emerged as the most widely recognized and validated program for treating children and adults with TS and CTD, demonstrating a significant validity and relevance in the recent literature [15; 33]. Among the studies, different treatment approaches for TD symptoms were employed: the majority used the CBIT program [15; 18; 19; 20; 31], also in its reduced version, the HRT [30], while others applied the ERP [21; 22; 29]. In particular, four studies examined an Internet-based adaptation of these interventions [19; 20; 21; 22], others adhered to the traditional face-to-face format [15; 29; 30; 31], and one used both modalities [18]. With the only exception of [PERSON] and colleagues [29], in all studies, children and adolescents received parental support [15; 18; 19; 20; 31; 21; 22; 30]. Three studies investigated a group-based adaptation of these interventions [29; 30; 31], while the others maintained the original individual administration format [15; 18; 19; 20; 21]. Despite structure variations, all treatment programs aimed at reducing or mitigating symptoms associated with tic disorders. The following section provides a brief overview of each treatment program  
**Comprehensive Behavioral Intervention for Tics (CBIT). ** CBIT is acknowledged as a primary therapeutic approach for managing tics [34]. Evidence supports CBIT's efficacy and safety in treating tics across pediatric and adult populations. It is a manualized behavioral therapy of eight sessions over ten weeks, with optional booster sessions, including psychoeducation, functional analysis, and relaxation training [15; 34]. The success of CBIT is based on the active engagement of patients, involving collaboration with the therapist, completion of assigned homework, and active participation in the sessions. **Internet-based guided self-help Comprehensive Behavioral Intervention for Tics (ICBIT). ** ICBIT represents an adaptation of CBIT: It is a caregiver-led self-help program with minimal therapist involvement, delivered through telepsychotherapy. The primary goals of this program are to provide both the child and the caregiver with specific behavioral and cognitive strategies for managing tics and to facilitate caregiver support, particularly for those unable to access in-person therapy [20]. ICBIT is commonly administered through an encrypted, purpose-designed online platform. An example included in this systematic review is the Barninternetprojektet (Child Internet Project, BIP) [27]. The intervention consists of nine consecutive joint child-caregiver modules delivered over a nine-week period, with a training duration of 20 to 30 min. The ICBIT incorporates a wide range of techniques, including psychoeducation, functional analysis of interactions, HRT, maintaining gains, and relapse prevention [20]. In addition to these steps, the CBIT-VoIP includes diaphragmatic breathing, progressive muscle relaxation, and behavioral rewards [19]. **Habit Reversal Training (HRT). ** The treatment is based on a structured program of ten chapters (modules) containing age-appropriate textual materials, animations, videos, and exercises over a period of ten weeks.