Investigating the Path From Non-Suicidal Self-Injury to Suicidal Ideation: The Moderating Role of Emotion Dysregulation
Article information
Abstract
Objective
Non suicidal self-injury (NSSI) and suicidal ideation are reliable antecedent events of suicide risk. To date, it remains unclear what implicit emotion regulation mechanisms are involved in these aspects and what is their role in the link between NSSI and suicidal ideation. The purpose of our study is to present evidence on the association between NSSI, suicidal ideation, and dysregulation of positive and negative emotions with the aim of providing empirical data useful in explaining the role of emotional dysregulation in the development of self-injurious and suicidal thoughts and behaviors, to contribute to the development of accurate and focused prevention and treatment directions.
Methods
The study was conducted on 1,202 individuals from a community sample (34.3% male; mean age of 30.48 [standard deviation= 13.32] years). Demographic information, including medical history, was collected in a form. We conducted analyses assessing suicidal ideation using the Beck Suicide Ideation Scale, NSSI using the Deliberate Self-Harm Inventory, and difficulties in negative emotion regulation and positive emotion regulation using the Difficulties in Emotion Regulation Scale and the Difficulties in Emotion Regulation Scale-Positive.
Results
Checking for age and gender, we found that both suicidal ideation and dysregulation of only negative emotions can predict NSSI. In addition, the results demonstrated that emotion dysregulation partially mediates the relationship between suicidal ideation and NSSI.
Conclusion
NSSI is traditionally distinguished from suicidal intent, even so it might be interesting to explore the intentional aspect in patients who present with persistent and severe self-injurious behaviors.
INTRODUCTION
Suicide is a problematic global public health phenomenon with high individual, societal, and economic impact [1]. Suicide is defined by the World Health Organization [2] as the act of deliberately killing oneself performed in full knowledge or expectation of its fatal outcome. The literature proposes a wide variety of sociodemographic, biological, and psychological risk factors to explain the antecedents of suicide [3]. In particular, from a psychological point of view, one of the main factors involved in the development of suicidal tendencies is the concept of psychache [4] being an unbearable mental pain for which suicidal thinking and behavior is perceived as the only solution. Influential theories of suicide stress the role of other risk factors as such as perceived heaviness, thwarted belongingness, feeling of being a burden for others, and acquired capacity for suicide [5,6]. Further, among the main factors accounting for the development of suicidal ideations and behaviors, a range of components have been identified included hopelessness [7], poor problem solving and tunnel vision [8], as well as emotion regulation deficits [9].
The emotion dysregulation perspective provides a theoretical framework relevant to the study of psychological correlates involved in the development of self-destructive tendencies, such as self-injurious behaviors and suicidal thoughts. In general, the framework of emotion dysregulation has emerged in psychology research as a key model for the study of various psychopathological frameworks and related facets [10], finding wide application for example in the investigation of aggression in psychopathic personality [11], in the exploration of personality facets in gambling disorder [12,13].
Specifically, the ability to regulate emotions refers to attempts made to influence or modify the intensity, duration, and quality of the emotions experienced [14]. Based on this conceptualization, Gratz and Roemer’s model [15] extended the construct of emotional regulation to include difficulties that limit in this competence, specifically in the components of awareness, understanding and acceptance of emotions, and ability to act in relation to the goal regardless of one’s emotional state that appear to be involved in the development of risk behaviors [16,17].
However, the most reliable predictors of suicide risk are self-injurious and suicidal ideations [18,19]. Self-injurious behaviors consist of the enactment of behaviors aimed at destroying, damaging, or altering one’s body, without having the intention to die [20], therefore, with reference to this description, in this paper we will consider self-injury in terms of non suicidal self-injury (NSSI). Differently, suicidal ideation refers to thoughts referring to the enactment of actions aimed at producing one’s own death. Self-injury and suicidal ideation are often associated with various psychopathologies, such as major depression [21], borderline personality disorder [22], eating disorders [23], and posttraumatic stress disorder [24]. Although they are distinct phenomena, NSSI and suicidal ideation can be defined as individual ideational and behavioral modes of response to the intensity of negative emotional states [25,26]. Indeed, recent findings indicate an association between difficulties in emotion regulation, particularly with perceived restricted access to emotional regulation strategies, and suicidal thoughts. This suggests that the perception of low self-efficacy in handling the emotional aspect of a situation may be an element involved in the development of suicidal ideation [27]. NSSI behaviors have also been shown to result in acts of self-harm serving as a mechanism to alleviate negative emotions in situations of high emotional burden [28]. Although these antecedents of suicide risk have been extensively investigated, findings on the type of link between suicidal ideation and NSSI need further clarification. In fact, although the strong association between NSSI and suicidal ideation is confirmed the evidence on the type of relationship between the two constructs reports conflicting data.
Recent results [29] show that self-injury behaviors are risk factors for the development of suicidal tendencies. In fact, self-injurious behaviors gradually expose the individual to pain to the point of habituation, resulting in a decreased fear of dying, considered a protective factor against suicide attempts exposing the individual to having more thoughts about death, exposing developing suicidal ideations, and sometimes actual suicide attempts, however need further investigation the pathway from suicidal ideation to NSSI.
From suicide ideation to NSSI
In light of the reciprocal relationship between suicidal ideation and NSSI, recent studies have examined suicidal ideation as a risk factor for involvement in NSSI behaviors [30]. Indeed, although several studies have investigated the pathway leading from self-injury to the development of suicidal ideation [31,32] the pathway from suicidal ideation to NSSI behaviors has been less investigated.
A recent study by Herzog et al. [33] explored the use of NSSI to curb thoughts referred to suicidal behaviors. Preliminary results show how, in addition to regulating dysphoric emotional states, NSSI can be enacted to regulate distress arising from suicidal thoughts. One possible explanation for this process could refer to the immediate goal of temporarily relieving distress, as a trade-off for the permanent solution that suicide represents [34]. Understanding what mechanisms might explain this relationship assumes theoretical and clinical relevance in order to provide insights into the risk factors for the development of NSSI behaviors, the dynamics underlying the reasons for self-injurious behaviors, and to contribute to the implementation of accurate and targeted interventions.
The emotion dysregulation framework
The model of emotion dysregulation [15] conceptualizes alterations in the ability to regulate emotions across six dimensions: low levels of emotional awareness, poor clarity of emotions, poor ability to maintain goal-oriented behavior when experiencing intense and negative emotions, poor control under the influence of negative emotional states, poor perceived ability to access various emotional regulation strategies, and a tendency to negatively judge internal emotional states.
A substantial body of research has supported the involvement of emotional dysregulation in various dysfunctional behaviors and psychopathologies [11,35,36] such as, for example, in the mechanisms of suicidal ideation and NSSI.
Suicide ideation and emotion dysregulation
Studies show a reciprocal relationship between emotional dysregulation and suicidal ideation, in fact, if a poor ability to regulate emotions can lead to thoughts that refer to suicide as strategies to alleviate emotional suffering, self-perception of a poor ability to regulate emotions, and ruminating thoughts about death also have a significant influence on the self-efficacy of regulation skills [37]. A recent systematic review [38] showed the presence of positively correlated associations between emotion dysregulation and suicidal ideation, particularly with regard to suicidal ruminations versus bodily experience [39]. In addition, the predictive value of emotion dysregulation with respect to the development of suicidal ideation and future suicidal intentions has been reported [40]. In general, studies recommend that difficulties in emotion regulation have an important function in suicidality, especially in individuals with pathological personality or other psychiatric comorbidities [41].
In line with this perspective, theoretical models that conceptualize suicidal phenomena and NSSI behaviors as functions of avoidance or escape from an emotional state intolerable to the subject [42] emphasize the role of emotion dysregulation in the origin of the development of ideas and behaviors of self-directed violence.
Emotion dysregulation and NSSI
Similarly, the literature on suicidal antecedents, and particularly on NSSI, conceptualizes this behavior as a maladaptive response to strong emotional states with negative valence [43]. Indeed, the results of the study conducted by Houben et al. [44] on the qualitative aspect of NSSI-related emotions provided relevant evidence on the clinical aspect of NSSI and stimulated reflections on the role of positive emotions. They showed that the likelihood of enacting NSSI behaviors is predicted by a high intensity of negative emotions and that, upon the occurrence of the self-injurious behavior and in the subsequent time interval, there is an increase in negative emotions, rather than emotional relief. Thus, if positive emotions are not the result of self-injurious regulatory behavior, they could also be studied. In fact, a recent systematic review of the literature on the topic has emphasized the conceptualization of NSSI as a maladaptive behavior to strong negative affect, and theoretical and empirical work has suggested that it has a coping function for emotional intensity resulting from poor regulation skills [43]. Most contemporary models of NSSI recognize the contribution of emotional dysregulation in the development and maintenance of NSSI; in particular, the experiential avoidance model of self-injury [34] suggests that NSSI has an avoidance function from unwanted emotional arousal that is exacerbated by deficits in emotional regulation skills and poor distress tolerance as triggers of NSSI behavior.
Current study
Based on the interesting findings on the central function of emotional dysregulation in the development of NSSI behaviors and suicidal ideation, the current study aims to further clarify the association between suicidal ideation, NSSI, and emotional dysregulation, and to fill a theoretical and empirical gap by including positive emotional regulation skills in the framework.
In fact, although the involvement of negative emotion dysregulation has been extensively studied, especially in clinical populations and in relation to suicide risk [45,46], there is a paucity of findings related to the role of positive emotion dysregulation in nonclinical populations. Research on positive emotion regulation difficulties is an area of considerable scientific interest that has grown in recent years, particularly in the study of various psychopathological forms [47]. Surprisingly, only a few studies have examined the link between positive emotion regulation, NSSI, and suicidal ideation. Therefore, it seems necessary to fill this gap and understand whether positive emotion regulation difficulty is involved in self-directed violence behaviors and ideas, and to study the link between NSSI and suicidal ideation in relation to difficulties in regulating emotional states in community samples, in order to understand how to intervene. The overall goal is to explore the type of link between suicidal ideation and NSSI behaviors in a nonclinical population through understanding the role played by dysregulation of positive and negative emotions. Specifically, based on recent findings demonstrating the function of NSSI as a regulation behavior for distress elicited by suicidal thoughts [33], we hypothesize that this relationship is mediated by the dimensions of emotional dysregulation based on the link that emotional dysregulation shows with the development of suicidal ideation and self-injurious behavior. Therefore, we hypothesize that individuals with emotional dysregulation are unable to cope with suicidal thoughts and seek to regulate the negative emotions aroused through NSSI. The aim is to contribute to the expansion of knowledge on the origin of self-directed violence behaviors by studying the role of emotional dysregulation in the relationship between suicidal ideation and NSSI.
METHODS
Participants
For the purposes of the study, a group of community participants was recruited through a convenience sampling technique. For participation in the study, subjects who were 18 years of age or older, literate and had provided informed consent for voluntary participation in the project were included. Excluded from the study were those under the age of 18 years, those who were non-literate, those with disabling physical impairments, those with psychopathologies, and those who had not provided informed consent for participation. Before completing the questionnaires, the purposes of the research and the information on privacy and anonymity were explained to the participants who were requested to sign an informed consent to participate in the research. The sample on which the analyses were conducted included a total of 1,202 participants (34.3% male), with an average age of 30.48 (standard deviation=13.32) years.
The research procedures were in conformity with the official guidelines of the American Psychological Association and were also approved by the Ethics Board of the Sapienza University of Rome (No. 21/2018).
Measures
This study is measured a battery of self-assessment questionnaires through which several domains were surveyed. Demographic information and clinical history were asked in an initial questionnaire created ad hoc for the purpose of the study.
Beck Suicide Ideation Scale
Suicidal ideation was assessed using Beck Suicide Ideation Scale (BSI) [48], a self-assessment tool that assess the intensity of suicide behaviors, attitudes, and plans. This scale is composed of 21-items. The first 19 ones have three options that evaluate the intensity of suicide ideation on a 3-point scale ranging from 0 to 2. Then, the ratings are totaled to obtain a total point score ranging from 0 to 38. The latter two items assess the previous number of suicide attempts and the severity of the intent to die referred to the last attempt. In our study, Cronbach’s alpha for the sum of the total score 0.80.
Deliberate Self-Harm Inventory
NSSI was assessed trough Deliberate Self-Harm Inventory (DSHI) [49,50], a self-report composed by 17 items. Each item entails 5 supplementary questions that explore different features of self-injury behavior, such as severity, frequency, form, and duration, and which examines retrospectively the development of that specific behavior. The information obtained from DSHI provide two variables: one continuous and one dichotomous. The first, which derived from the sum of the score of each item’s frequency questions, measures the rate of reported self-harm behavior. The second, dichotomous variable, involves that is assigning score of “1” if participant answered “yes” to any of the 17 items; otherwise, if participant did not answer “yes” to any items of DSHI, he receives score of “0.” In our study, Cronbach’s alpha was 0.88.
Difficulties in Emotion Regulation Scale
Difficulties in the regulation of negative emotions were assessed using the Difficulties in Emotion Regulation Scale (DERS) [15,51]. This instrument is a self-report questionnaire that measures overall emotion dysregulation, obtained from the sum of six subscales that assess different regulation features namely: 1) impulse-control difficulties; 2) difficulties engaging in goal-directed behavior; 3) lack of emotional awareness; 4) lack of emotional clarity; 5) limited access to effective emotion-regulation strategies; and 6) non acceptance of emotional responses. Participants are equested to mark how frequently the items apply to themselves, with Likert-type scale answers from 1 (“never”) to 5 (“always”). In our study, all Cronbach’s alphas were satisfying, ranging from 0.81 (clarity) to 0.94 (DERS total score).
Difficulties in Emotion Regulation Scale-Positive
Difficulties in the regulation of positive emotions were assessed trough Difficulties in Emotion Regulation Scale-Positive (DERS-P) [47,52]. This scale is a 15-item self-report questionnaire shaped on the original DERS [15] to evaluate difficulties arising from experiencing positive, rather than negative emotions DERS-P examines three domains of emotion regulation, namely: 1) acceptance of positive emotions; 2) ability to engage in goal-directed behavior when experiencing positive emotions; and 3) ability to control impulsive behaviors when experiencing positive emotions. Participants are asked to indicate how often the items apply to themselves, with Likert-type scale responses ranging from 1 (“never”) to 5 (“always”). Raised scores indicate a higher difficulty in the regulation of positive emotions. In this study, Cronbach’s alphas ranged from 0.80 (acceptance of positive emotions) to 0.88 (DERS-P total), indicating a good reliability.
Data analysis
For the analyses conducted in the current study, we used IBM SPSS version 27.0 (IBM Corp., Armonk, NY, USA) software and PROCESS macro created fot the sotfware. Descriptive statistics were performed including mean and standard deviation calculation and computation of frequencies. Correlation analyses were then performed (Pearson’s r) followed by hierarchical multiple linear regressions used to test our mediation hypothesis.
RESULTS
Associations between suicidal ideation, NSSI, and emotion dysregulation
To explore the relationships between suicidal ideation, NSSI, and emotion dysregulation, partial correlations, controlling for age and gender, have been performed and are displayed in Table 1. Overall, it resulted that DSHI scores were highly correlated both with BSI scores (r=0.43; p<0.001) and with difficulties to regulate positive and negative emotional status with coefficients ranging from 0.30 (DERS total scores) to 0.11 (goals).
Results of descriptive analysis (age, gender)
Concerning suicide ideation, we obtained similar results: it significantly and positively correlated with both DERS and DERS-P total scores and subscales, with coefficients ranging from 0.33 (DERS total scores) to 0.14 (awareness).
With the aim of exploring which dimensions would predict NSSI, we ran a hierarchical multiple linear regression entering age and gender in the first step, total index of BSI in the second one, total index of DERS in the third model, and DERS-P in the final one. As displayed in Table 2, we found that both BSI and DERS predicted DSHI scores, whereas DERS-P was a non-significant predictor of NSSI.
Partial correlations, controlling for age and gender, between non-suicidal self-injury, suicidal ideation, and emotion dysregulation (positive and negative)
The mediating role of DERS in the relationship between suicide ideation and NSSI
In order to explain the trajectory by which suicide ideation leads to NSSI behavior, we tested the mediating role of emotion dysregulation. As showed in Table 3, we first ensured that suicide ideation predicted NSSI (Phase 1), that suicide ideation predicted difficulties in emotion regulation (Phase 2), that emotion dysregulation was a meaningful predictor of NSSI beyond the role of suicide ideation (Phase 3). Finally, in the fourth step, we examined the hypothesis that the link between suicide ideation and NSSI would have been mediated by emotion dysregulation. Results indicated that the pathways by which suicide ideation leads to NSSI is partially mediated by levels of emotion dysregulation (Figure 1).
Hierarchical multiple regression predicting NSSI from ideation of suicide and difficulties in positive and negative emotion regulation, controlling for age and gender
Mediating model of emotion dysregulation in the relationship between suicidal ideation and non suicidal self-injury. BSI, Beck Suicide Ideation Scale; DSHI, Deliberate Self-Harm Inventory; DERS, Difficulties in Emotion Regulation Scale.
DISCUSSION
The present state of knowledge reports that emotion dysregulation plays a core function in the development of ideas and behaviors of self-inflicted violence, such as NSSI and suicidal ideation.
However, although the relationship between these two important predictors of suicide risk has been investigated, the results need further clarification.
Indeed, although the findings confirm that self-injurious acts are objective physical indicators of suicide ideation risk [53], fewer studies have investigated the trajectory leading from suicide ideation to NSSI acts. These include the NSSI’s antisuicide model, which views self-harm in terms of a coping mechanism for resisting the urge or idea to attempt suicide [34], and recent preliminary findings [33] have shown that NSSI can be enacted to control suicide-related ideas and regulate subsequent distress. With the aim of deepening our comprehension of the mechanisms underlying the link between suicidal ideation and NSSI, we therefore investigated the role of dysregulation of positive and negative emotions within this relationship.
First, our results confirmed the existence of a significant relationship between suicidal ideation and NSSI. In accordance with the findings of previous studies that had found an increase in NSSI in association with an increase in suicidal ideation and attempts in adolescents [30], our results replicated this association in a sample of adults confirming the existence of a consistent relationship between these two variables across the life span. However, this hypothesis needs further validation through longitudinal studies.
Second, regression analyses confirmed the role of suicidal ideation as a predictor of NSSI, confirming the hypothesis of suicidal ideation as a potential risk for the development of NSSI. This interesting result contributes to the understanding of the development of NSSI behaviors, which could result from an attempt to find relief and regulate emotions of distress, arising from thoughts related to death, that the individual is unable to regulate otherwise.
However, beyond the theoretical assumptions related to this pathway, these findings underscore the importance of assessing and monitoring the aspect related to suicidal ideations and thoughts among patients who report NSSI.
In addition, to extend the knowledge regarding the relationship between suicidal ideation and NSSI, we investigated the role of mechanisms related to emotion dysregulation. The results show that both suicidal ideation and NSSI were significantly correlated with difficulties in regulation of positive and negative emotions. This result is not surprising, being line with literature that supports the existence of a significant association between difficulties in emotion regulation and both suicidal ideation and NSSI [27,31] and argues that NSSI can be interpreted as a maladaptive attempt to regulate negative emotions.
Specifically, The results of Rizvi and Fitzpatrick’s [54] study examining whether individual differences in a set of discrete emotions moderate changes in suicidal ideation and NSSI ideation over the course of treatment demonstrated the involvement of specific emotions that play a role in the development of NSSI and suicidal ideation. Specifically, the study identified the involvement of emotions such as hostility/rage, fear, shame/guilt, and sadness, showing that dysregulation of shame and guilt are more deeply rooted in the development of NSSI and suicidal ideation. Also, a further innovative aspect of our study relates the analysis of the relationship between suicidal ideation, NSSI, and the difficulty in regulating positive emotions that can cause negative secondary emotional responses such as NSSI and suicidal ideation.
The evidence suggested a relation of dysregulation of positive emotions, suicidal ideation, and NSSI behaviors. However, when we tested the predictive value of dysregulation of positive emotions toward NSSI, it was not predictive.
What we demonstrated opens an interesting new scenario yet to be explored, suggesting that the internal dysregulatory mechanisms involved in self-injurious and suicidal behaviors are more complex and also involve positive emotions. Indeed, although dysregulation of positive emotions has not been found to be a reliable predictor of NSSI, the association has been demonstrated. This allows for the hypothesis that NSSI behaviors and suicidal ideation may be modes of response to the intensity of emotions, rather than their emotional coloring. In fact, an increasing number of studies have demonstrated the central role of difficulty regulating positive emotional states in a number of psychopathological conditions in which high-intensity emotions are involved, including post-traumatic stress disorder, alcohol abuse, bipolar disorder, and gambling disorder [55,56]. In particular, difficulty in accepting positive emotional states in a nonjudgmental manner seems particularly involved in suicidal ideation. This result is consistent with research that has documented the association between depressive symptomatology, which is strongly associated with suicidal ideation, and the propensity to dampen positive emotional states in response to the belief that one is unworthy of positive events [57].
Overall, these results recommend the hypothesis that basic depressive beliefs and feelings of unworthiness, associated with suicidal ideation may explain the relationship between difficulty accepting positive emotional states and suicidal ideation.
Despite the promising results, in hierarchical regression only dysregulation of negative emotions predicted suicidal ideation, and this result can be attributed to several factors. It is possible that because the role of positive emotions in NSSI is still unclear, dysregulation of positive emotions is not a predictor of this behavior, but that there is a more complex relationship involving other variables. Another hypothesis could be related to the composition of the sample, in fact, it is possible that in the community sample the level of dysregulation of positive emotions is less pronounced than in the clinical samples. The suggestion is therefore that future studies may explore the relationship between dysregulation of positive emotions and NSSI in different clinical samples.
Finally, mediation analyses partially confirmed the mediating role of emotion dysregulation in the relationship between suicidal ideation and NSSI, confirming the central function performed by emotion dysregulation mechanisms related to the development of NSSI behaviors.
Thoughts and ideations referring to suicide would appear to aggravate the suffering of the individual who, unable to cope with the intensity of his or her emotional states, enacts NSSI in order to regulate and relieve emotional tension [37].
Overall, the results obtained confirmed our hypotheses, in line with the existing literature that considers suicidal ideation as a risk factor in self-injurious behaviors [58] and observed the relevant role of emotion dysregulation in suicidal and self-injurious phenomena [27], adding dysregulation of positive emotions—to the picture for the first time in a non-clinical sample. Moreover, the empirical data obtained may provide their contribution, from a clinical point of view, for a more accurate understanding of the dynamics of NSSI as an action enacted by an individual attempting to control the distress resulting from suicidal ideation in the presence of a difficulty in regulating negative emotions. Thus, an intervention aimed at ameliorating emotional regulation capacities could be targeted to reduce acts of NSSI and to cope with suicidal ideation. Similarly a preventive intervention on suicidal risk preventive may benefit from a monitoring of individuals with poor emotional regulation skills [31].
Limitations and future research directions
Although rigorously conducted, this work is not without its limitations. In fact, our study was conducted on a sample composed of individuals from the general population, although rather large this does not provide an opportunity to generalize the results to clinical samples that might show different and peculiar characteristics that should be further investigated with subsequent studies. Also, the descriptive analyses dwelt on the study of gender and age. Later studies could also analyze other sample characteristics such as socioeconomic status and educational level. Moreover, another limitation concerns the lack of measurement of potential confounding variables, such as depressive and anxiety symptomatology. In fact, our study aimed to specifically assess the trajectory from suicidal ideations to non-suicidal acts of self-harm, attending to the mediating role of emotional dysregulation. Further studies could explore this pathway in populations with significant levels of anxiety or depression.
In addition, self-injurious behaviors were measured with a dichotomous instrument, not allowing in-depth investigation related to the motivations behind NSSI.
Future research could explore the motivational aspect related to NSSI to better understand the relationship with both dysregulation of negative and positive emotion. Finally, in order to test such a large sample, self-report instruments were used in this research, which, as is widely known in the literature, may exhibit bias related to social desirability.
In conclusion, although NSSI is traditionally distinguished from suicidal intent because of the absence of the aspect related to the desire to die, it might be interesting to explore the intentional aspect in patients who present with persistent and severe self-injurious behaviors. In addition, it might be useful to replicate our results by also studying other mechanisms related to the construct of emotional dysregulation (e.g., alexithymia, dissociation) that can influence the link of suicidal ideation and NSSI.
Notes
Availability of Data and Material
The data that support the findings of this study are available on request from the corresponding author [PV].
Conflicts of Interest
The authors have no potential conflicts of interest to disclose.
Author Contributions
Conceptualization: Sara Beomonte Zobel, Patrizia Velotti. Data curation: Sara Beomonte Zobel, Serena Bruno. Formal analysis: Sara Beomonte Zobel, Guyonne Rogier. Investigation: Sara Beomonte Zobel, Paola Torru. Methodology: Patrizia Velotti. Project administration: Sara Beomonte Zobel. Supervision: Patrizia Velotti. Writing—original draft: Sara Beomonte Zobel, Serena Bruno, Paola Torru. Writing—review & editing: Guyonne Rogier, Patrizia Velotti.
Funding Statement
None