## 1 Introduction  
Depression is a widespread mental health disorder that affects both adults and young people, including children and adolescents. The World Health Organization has reported that depression affects approximately 280 million people globally [1]. The number of depression cases was steadily increasing in parallel with the world population [2] until the onset of the COVID-19 pandemic, after which it rose dramatically [3]. Despite the significant scale of depression and the substantial personal and governmental social costs, the condition remains insufficiently recognized--even though it accounts for 30% of years lived with disability (YLDs) for mental disorders worldwide [4]. The pooled prevalence rate of depressive disorder (DD) among European children and adolescents is 1.7% (95% CI: 1.0-2.9%) [5], while the global prevalence is 2.6% (95% CI 1.7-3.9%) [6]. Prevalence rates are 4.2 times higher among secondary school children [5], with a median age of onset for the first symptoms of 15.5 years [7]. DD imposes a significant burden on young people, ranking among the leading causes of years lived with disability due to mental health conditions [8]. According to current classification systems for mental disorders [9; 10], DD encompasses a broad group of mood disorders, including disruptive mood dysregulation disorder, major depressive disorder, persistent depressive disorder, and others. The core symptoms required for diagnosing specific forms of DD are grouped into three main domains [10]; affective (such as depressed mood or irritability in youth, and a marked loss of interest or pleasure), cognitive-behavioral (including impaired concentration or indecisiveness, feelings of low self-worth or guilt, hopelessness, and suicidal behaviors), and neurovegetative (such as disrupted sleep, changes in appetite or weight, psychomotor agitation or retardation, and reduced energy or fatigue). These symptoms collectively impair an individual's ability to function in daily life [10]. In addition to classical affective and cognitive-behavioral symptoms, psychomotor symptoms are an integral component of depressive disorder (DD) symptomatology [11]. Studies focused specifically on DD consistently identify motor alterations in gross and fine motor activity, discrete body movements, speech, and motor reaction time. For instance, gross motor changes include slow gait, reduced step and stride length and width, slower turning and reaction times, and overall abnormal movements [12]. More subtle findings involve fine motor changes such as alterations in speech patterns [13] and slower handwriting performance [14]. Neuropsychological studies link psychomotor symptoms predominantly to impaired processing speed, manifested as slower movement onset, preparation, and execution [15]. Psychomotor retardation is regarded as one of the key aspects of DDs [9; 10] involving both motor and cognitive impairments that affect speech, movement, and ideation [16]. It is currently defined as a visible, generalized slowing of movements and speech [10] and is recognized by features such as a fixed gaze, poor maintenance of eye contact, gross psychomotor slowing--including limited movement of the hands, legs, torso, and head--slumped posture, and related signs [17; 18]. It is important to note that the term psychomotor retardation does not equate to cognitive and psychomotor developmental delay observed in neurodevelopmental disorders [19]. Assessments of psychomotor retardation are based on three primary approaches: clinical rating scales (typically including items related to psychomotor disturbances and cognitive or motor aspects of retardation), objective measures (assessing aspects of speech, eye movements, or motor activity), and cognitive measures (primarily evaluating reaction times) [16; 20; 21; 22]. Drawing tasks are considered simple yet effective objective tools, relying on kinematic analysis of drawing and handwriting movements to enable precise, quantifiable evaluation of motor abnormalities in depression [14; 16; 21].