Mental disorders (MDs) in children and adolescents are highly prevalent, even in high-income countries [1]. The prevalence increased due to the global impact of COVID-19 on MDs in this population [2]. The pathogenesis of MDs is thought to be a complex process influenced by individual and environment factors [3]. Generally, MDs affect young people’s emotional state (mood; [4]) and are characterized by atypical perceptions, behavior, and relationships [5]. This, in turn, limits young people’s participation in age-appropriate activities, quality of life, and overall well-being [5]. Moreover, young people with MDs often lose access to their creativity and spontaneity, experiencing despair in the face of daily challenges [6] and heightened levels of stress [7, 8].

In general, stress is associated with multifaceted behavioral and biological responses, primarily by activating the hypothalamus–pituitary–adrenal (HPA) axis [9]. The secretion of cortisol occurs under the influence of the circadian rhythm in the adaptation process to environmental challenges. Thus, salivary sCort is a correlate of the biological stress response and is essential to maintain homeostasis [9]. Over the course of the day, the highest level is reached in the 30–45 min after waking up, the lowest is reached around midnight. The early afternoon is an appropriate period for evaluating potential alterations in the activity of the HPA axis, triggered, for instance, by arts-related activities [10]. Stress may cause alterations in immune function [11]. Immunoglobulin A, a first-line mucosal protector against pathogens [11], is produced in response to physical and psychological stress. It is also affected by an individual’s emotional state [12].

The causal connection between MDs and stress appears bidirectional. For example, biographical stress experiences in early life may contribute to MDs [13]. However, the development of MDs is also associated with the dysregulation of neuroendocrine system activities and underlying stress responses [14]. Therefore, it is likely that both genetic components and gene–environment interactions give rise to MDs from an early age [15].

Previous studies have addressed sCort and sIgA alongside other biomarkers in the context of arts participation, for example, with respect to amateur adult singers [16, 17]. Findings suggest that favorable short-term psychobiological changes can occur in response to such interventions, but there is little information with respect to vulnerable groups including children and adolescents with MDs [18, 19].

Creative arts therapies and interventions are common strategies in child and adolescent psychiatry (e.g., [20,21,22]). However, the empirical evidence appears mixed. For example, cognitive behavioral therapy can be more effective than arts or music therapy for reducing symptoms of depression in children [23]. By contrast, a meta-analysis of 11 experimental studies on music therapy found a moderate positive effect on clinical outcomes but identified a need for more studies in clinical settings [24]. Finally, participation in activities such as listening to and making music can elicit positive feelings and influence stress symptoms in young people with mental health issues [18]. Creative arts engagement can reduce anxiety and depression symptoms in young people [25], while enhancing self-confidence and self-esteem, a sense of achievement and empowerment, social skills, positive behavioral changes, and resilience [26,27,28]. However, a systematic review of adjuvant interventions suggests that creative arts participation appears to be beneficial but, overall, less effective than sports and yoga [29].

It is of note that the term “therapeutic” typically implies the involvement of a trained therapist, while delivery through care staff or external providers suggests an emphasis on leisure or distraction activity [28]. However, beneficial effects can occur, irrespective of the specific therapeutic goal settings. For example, Grebosz-Haring and Thun-Hohenstein [6, 18] argue that engagement in arts activities can stimulate creative processes to increase self-confidence and self-efficacy, and bring distraction, attention, imagery, joy, and pleasure. The arts can also encourage young people to engage in more positive self-reflections and social interactions.

Creative arts interventions for hospitalized children and adolescents with diagnosed MDs produced mixed findings (e.g., [18, 22]), probably due to conceptual and methodological flaws, which question the validity of conclusions (e.g., [30]). Therefore, it is unclear, how different types of arts activities (musical vs. non-musical) affect young people with MDs in a clinical setting. Further, there is also a need to study the feasibility and treatment effects with respect to the individual needs and paths of recovery and rehabilitation in this vulnerable group.

The present study is part of a 2-year pilot project to assess the feasibility of a music- and arts-based intervention protocol for hospitalized children and adolescents with MDs. Specifically, we were interested in the effectiveness of short-term intensive music and arts activities on behavioral measures of mood, quality of life, and well-being as well as on biological markers related to stress and immune function. These interventions included choir singing, textile design, drama, and clownery, which were incorporated into standard treatment routines. Results of specific subsets of the protocol concerning music-related interventions were published elsewhere [18].

We asked the following research question:

What are the effects of short-term arts-based interventions for young people with MD on (a) behavioral measures of mood, quality of life, and well-being as well as on (b) the concentrations of sCort and sIgA in a clinical setting?

We expected that the music and creative arts activities would induce positive changes in psychological outcomes such as improvement of self-reported mood state, quality of life, and psychological well-being (H1). Furthermore, we also assumed positive changes in neuroendocrine stress (HPA axis) and immune function in terms of a reduction in sCort and an increase in sIgA (H2).

A subsidiary goal of the study was to investigate the compliance, appropriateness of inclusion criteria, attrition, dropout rate, and possible factors that might facilitate or compromise participation in clinic-based arts intervention. It is of note that individual mental conditions could interact with preferences in the different types of arts activities. Therefore, it is important to consider individual accounts of participation. However, these data are subject to a separate investigation and will not be part of the present paper. Finally, we sought to reflect on the acceptability of gathering biomarker data during a clinical intervention in the clinical setting.