Phd in PSYCHOLOGY AND SOCIAL NEUROSCIENCE

Thesis title: Sadness and Somatic Symptoms in Adolescence

GENERAL INTRODUCTION Over the past few decades, there has been a significant increasing in psychosomatic problems associated with emotional distress and depression among adolescents (Costello, Copeland & Angold, 2011). Indeed, there has been a growing concern worldwide that the adolescents’ mental health is much more at risk than previous generations, as younger people currently appear to be much more likely to develop mental health problems (Kieling et al., 2011). A growing focus is emerging in the literature especially on somatic symptoms, which are physical complaints without a clear pathological origin or, even an organic cause is revealed, when functioning, social impairment and resulting discomfort are far excessive compared to what it would be expected from the features of physical pathology itself (Campo, Jansen-McWilliams, Comer & Kelleher, 1999; Joychan Kazi & Patel; 2016). They represent a specific subdomain among the overall internalizing symptoms (Achenbach, 1991) and the term somatization constitutes the underlying mechanism by which distress is experienced in the form of a physical symptom (Ibeziako & Bujoreanu, 2011). The most frequent somatic symptoms reported by youths are headache, abdominal pain (between 10% and 30% of youths [Campo 2012]), followed by fatigue, stomach pain and nausea, headaches, musculoskeletal pain, dizziness (Eminson, 2007; Schulte & Petermann, 2011). Several epidemiological and clinical studies suggested that recurrent somatic symptoms among children and adolescents are quite common both in clinical and community samples (e.g., Ask, Waaktaar, Seglem & Torgersen, 2016; Beck 2008; Campo e Fritsch 1994; Masi, Favilla, Millepiedi & Mucci, 2000; Ruchkin & Schwab-Stone, 2014) and are generally associated with increased use of health care services (van Geelen, Rydelius & Hagquist, 2015) as well as with significant impairment on youths’ daily life (Rapee et al., 2012). Moreover, when somatic symptoms are associated with unpleasant thoughts and feelings about them, they can also lead to real psychopathological disorders (Creed et al., 2012). Thus, somatic symptoms’ onset often had a negative impact on youths’ daily commitments since they force youths to give up participation at school or physical activities, harming also academic achievement (e.g., Kelly et al. 2010; Van Ravesteijn et al., 2009). Given their detrimental effects on youths' overall well-being and psychosocial adjustment, it is critical to identify associated factors which constitute somatic symptoms’ determinants from a developmental perspective. Overall, literature about this field, suggested that somatic symptoms’ prevalence is quite low among preschoolers (Campo & Fritsch, 1994; Domenech-Llaberia et al., 2004; Zuckerman, Stevenson & Bailey, 1987) while tend to increase with aging (Campo, Jansen-McWilliams, Comer, & Kelleher, 1999). A growing body of researchers suggested that somatization tendency increases across development, reaching a peak during transition to adolescence (Twycross, Dowden, Bruce, 2009) especially among females (e.g., Kaltiala-Heino, Marttunen, Rantanen, and Rimpela; 2003; Larsson, 1991; Rauste-von Wright & von Wright, 1981; Rhee, Holditch-Davis & Miles, 2005). A greater vulnerability to somatization would emerge in early adolescence and it may be a risk factor to maintain chronic somatic symptoms in adulthood (e.g., Barkmann et al., 2015; Dunn et al., 2011; Jansenns et al., 2014; Nummi et al., 2017; Mulvaney et al, 2006). Thus, puberty might be a crucial turning point during which gender membership would start to play a key role in somatization’s incidence (Aro & Taipale, 1987; Rhee, 2005), as from this period females would tend to report more than twice as many somatic symptoms as boys (Achenbach et al., 1989; Offord et al, 1987; Rauste-von Wright & von-Wright, 1981). It is plausible as puberty may act as triggers of changing on mood and behavior’s mechanisms (Susman, Dorn, & Schiefelbein, 2003). Although studies on somatic symptoms’ incidence in transition to late childhood to adolescence are recently increased, there are still gap in literature about specific emotional and cognitive-behavioral components underlying their onset in a developmental perspective. Indeed, empirical studies with both children and adolescents’ populations have highlighted that higher negative mood (including sadness, anger, and fear) is associated with higher somatic symptoms’ levels (e.g., Villanueva Badenes, Prado-Gascó & González Barrón, 2016; Villanueva, Górriz, Prado-Gascó & González, 2015; Rieffe et al., 2004). However, these studies focused on a general negative affect, without examine systematically the specific association between sadness, as a discrete negative emotion, and somatic symptoms, as a specific internalizing symptoms’ subdomain. Most part of literature has extensively investigated the association between anxiety and somatization, but little is known regarding the relationship between sadness and somatization. Nonetheless, the link between depressed and somatic symptoms is well established even among youths of both community and clinical samples’ reporting multiple somatic symptoms (e.g., Bohman et al., 2010; Campo & Fritsch, 1994; Dhossche et al, 2001; Egger et al, 1999; Harma, Kaltiala-Heino, Rimpela, & Rantanen, 2002; Larsson, 1991; Poikolainen, Kanerva, & Lonnqvist, 1995). Moreover, most part of the contributions which have specifically examined the association between negative emotions and somatic symptoms focused exclusively on the inter-individual differences (by analyzing the between-person variance) without exploring the role played by intra-individual differences (by analyzing the within-person variance). There are still few studies that have examined how individual daily variations of specific negative emotions’ (including sadness) levels may be associated with greater internalizing symptoms (e.g., Arbel et al., 2021; Rothenberg et al., 2019). However, these studies have not focused specifically on somatic symptoms. Similarly, several studies have also found that poor self-regulatory skills are associated with greater internalizing symptoms (e.g., Compas et al., 2004; Loukas & Roalson, 2006; Moustafa et al., 2017; Onat et al., 2019; Yu et al., 2020). However, studies examining the link respectively between self-regulatory abilities, in terms of high effortful control, and self-regulatory impairment, in terms of impulsivity, and somatic symptoms as specific subdomain among the overall internalizing problems. As for other internalizing outcomes, it is also possible for somatic symptoms’ onset to be associated to individual predispositions related to specific mechanisms of reactivity and regulation during transition to adolescence. Thus, this dissertation is aimed to fill the aforementioned gaps in literature. The overall aim of the present dissertation is to analyze the association between sadness as a discrete negative emotion and somatic symptoms as specific internalizing subdomain in a developmental perspective. Specifically, the first aim is to identify the normative trajectories of somatic symptoms from pre- to middle adolescence, examining the predictive role of sadness considering three facets: sadness reactivity (i.e., as a temperamental tendency to experience sadness), sadness coping (i.e., the ability of adopting adaptive strategies to deal with sadness) and depressive rumination (i.e., a maladaptive strategy to deal with sadness), focusing on inter-individual differences. The second aim is to investigate the bidirectional associations among self-regulation, sadness reactivity and somatic symptoms in transition from late childhood to pre-adolescence, focusing on an inter-individual perspective on two different temperamental component of self-regulatory abilities that is effortful control (i.e., a top-down component of an effective self-regulation) and impulsivity (i.e., a multi-componential construct [including both top-down and bottom-up components] typically interpreted as breakdowns in self-regulation). Finally, the third aim is to examine the association between sadness and somatic symptoms extending the investigation also to the intra-individual differences (in addition to inter-individual ones). Thus, we considered two nuances of sadness: a daily sadness instability (i.e., the individual daily fluctuations of sadness level [within-person variability]) and the overall sadness mean level (i.e., the general tendency to experience over the time span considered [between-person variability]), examining their contribution on somatic symptoms, testing the moderator effect of atypical (clinical) condition (compared to normative developmental condition) and the replicability of results within two different cultures.