Introduction

Eating disorders (hereinafter EDs) have been growing in relevance in social-healthcare due to their severity, complexity, and difficulty in determining a specific diagnosis and treatment (^{Frieiro et al., 2022}), becoming a major public health problem in developed countries (^{Oliva et al., 2012}; ^{Trompeter et al., 2022}). In Spain, research estimates that EDs are already the third most prevalent chronic illness among the adolescent population group (^{SEMG, 2018}).

EDs are defined as severe mental disorders characterized by pathological attitudes and behaviors in relation to eating (^{APA, 2013}). They have in common the over-valuation of the figure and weight, body dissatisfaction, and the permanent desire for thinness, which are present during all stages of the disease (^{APA, 2013}). Four main entities stand out: anorexia nervosa (AN hereafter), bulimia nervosa (BN), eating disorders not otherwise specified (EDNOS), and binge eating disorder (BED).

Furthermore, EDs emerge to a large extent during adolescence or early adulthood (^{Trompeter et al., 2022}). The average age of onset is in adolescence, since this stage is associated with numerous physical and psychological changes, and there is widespread body dissatisfaction among the adolescent population (^{Nelson et al., 2021}).

These are disorders of multifactorial origin where genetic, biological, psychological, and sociocultural risk factors are involved (^{Frieiro et al., 2022}; ^{Mills et al., 2018}; ^{Murray et al., 2022a}; ^{Rojo et al., 2017}). Regarding the biological factors, studies on genetics have concluded that the heritability of EDs is high (^{Rojo et al., 2017}). Other studies point to EDs being partially elicited by a disconnection between inhibitory and reward control networks in the brain (^{Murray et al., 2022a}) or by sex differences in the cerebral gray matter (^{Murray et al., 2022b}). Also, in relation to biological mechanisms, it is worth noting the existence of numerous studies (^{Babio et al., 2009}; ^{Espinoza et al., 2010}; ^{Gutiérrez et al., 2015}) that propose body mass index (BMI hereafter) as a predictor of EDs, taking into account its relationship with obesity. Thus, a high BMI is a risk factor for the occurrence of EDs (^{Espinoza et al., 2010}).

Regarding psychological factors, some of the variables associated with increased vulnerability are excessive rigidity, need for control, perfectionism, feelings of inefficacy, inadequate emotional regulation, and low self-esteem (^{Frieiro et al., 2022}; ^{Holland et al., 2013}; ^{Jacobi et al., 2018}; ^{Trompeter et al., 2022}). Furthermore, different authors (^{Bakalar et al., 2015}) analyze the comorbidity between ED and other psychiatric disorders. They highlight a high percentage in the presence of anxiety disorders, impulse control disorders, and affective disorders such as depression, noting that these all have an onset prior to the development of ED.

Regarding family risk factors, the influence of the family on the development of ED has been studied from different perspectives (^{Jewell et al., 2016}; ^{Kluck, 2010}; ^{Mensi et al., 2022}; ^{Stillar et al., 2023}). For example, previous studies claim that there is an increased risk of developing an ED in families in which negative parental attitudes towards food, weight, and the figure are predominant (^{Kluck, 2010}), or even when parents themselves experience fear of being actively involved in their children's recovery process (^{Stillar et al., 2023}).

Finally, in reference to sociocultural factors, the social context unquestionably influences the development of EDs (^{Amaya-Hernández et al., 2017}), which is why they appear in a much higher proportion in societies where thinness is emphasized. In addition, the important influence of the media and social networks should be highlighted. According to ^{Mills et al. (2018)}, frequent exposure to the internet and social networks results in increased body dissatisfaction, drive for thinness, and high body surveillance. Some research suggests that internalization of the thin ideal may mediate the relationship between exposures to images of ideal beauty prototypes and body dissatisfaction, resulting in an increased likelihood of developing symptoms of ED (^{Bair et al., 2012}).

Therefore, given the relevance of EDs due to their expansion in the population, the psychological repercussions caused by their symptomatology, and the impact on the health of those who suffer from them, the need is justified to investigate in greater depth the role played by the risk factors associated with their development and maintenance. Moreover, considering that the incidence of EDs is occurring at increasingly younger ages, it is of vital importance to understand which factors are related to their onset (^{SEMG, 2018}). In this way, and taking into account that early detection when dealing with ED, significantly increases the possibility of a favorable evolution and recovery (^{Trompeter et al., 2022}), the need for further progress in the etiological understanding of ED is evident. Furthermore, it should be noted that in recent years no systematic review of the scientific literature on the risk factors related to ED in Spanish adolescents has been published in scientific databases.

Thus, the general aim of this article is to carry out a systematic review of the scientific literature on the risk factors related to the development of ED in Spanish adolescents. To this end, the following specific objectives are proposed: to identify the different types of factors involved in the development of ED in Spanish adolescents, to analyze the main results derived from the studies selected for the systematic review, and to elucidate the main psychological variables associated with these risk factors.

Method

Selection and Data Collection Procedure

Two reviewers (LCR and MJ) independently selected the publications that matched the eligibility criteria. In case of disagreement, the selection or exclusion of the publication was specifically discussed between the two reviewers until a final agreement was reached.

The corresponding PRISMA Flow Diagram is shown in Figure 1.

Figure 1. Below Shows the Corresponding PRISMA Flow Diagram. 

Finally, 17 articles met the eligibility criteria and were chosen for the systematic review.

Results

The main characteristics of the articles included in the systematic review are presented below in Table 2.

Thus, the analysis of the results will be carried out by grouping the articles according to the risk factors to which they refer.

Discussion

The aim of this article was to conduct a systematic review of the scientific literature on the risk factors related to the development of ED in Spanish adolescents.

In reference to the biological risk factors, one of the most studied variables is BMI. Current research affirms that BMI is a significant predictor of the development of ED (^{Gutiérrez et al., 2015}). These data are consistent with the results of the present review, since all the included studies that analyze this relationship conclude that adolescents with a high BMI present a higher risk of developing an ED (^{Babio et al., 2009}; ^{Espinoza et al., 2010}; ^{Ferreiro et al., 2011}; ^{Gutiérrez et al., 2015}; ^{Veses et al., 2011}). Another of the biological risk factors studied is the influence of genetics (^{Mas et al., 2013}). The results of the aforementioned research are in agreement with the evidence of the current scientific literature on the heritability of EDs (^{Rojo et al., 2017}).

Regarding the psychological risk factors, psychological comorbidity has been identified as a predictor of ED (^{Jacobi et al., 2018}). The results of ^{Ferreiro et al. (2014)} show a significant relationship between the presence of depressive symptoms and the risk of ED. The results of the research by ^{Babio et al. (2009)} also show a significant relationship between the risk of suffering from ED and presenting symptoms of generalized anxiety disorders. Both relationships are consistent with recent research outside the Spanish setting (^{Jacobi et al., 2018}). Regarding sex differences, some studies argue that the relationship between depressive symptoms and the risk of ED is essentially the same for boys and girls (^{Ferreiro et al., 2014}), however, other studies point out that the presence of emotional disturbances are a female-specific predictor (^{Babio et al., 2009}). On another note, research by ^{Ferreiro et al. (2011)}, ^{Espinoza et al. (2010)}, and ^{Gutiérrez et al. (2015)} relate an increased risk of ED to body dissatisfaction or negative body image. Similarly, another of the main psychological risk factors is low self-esteem. Thus, the results of the research included in the present systematic review (^{Mora et al., 2022}; ^{Gutiérrez et al., 2015}) are consistent with other research published in the literature (^{Frieiro et al., 2022}) in concluding that there is a significant association between low self-esteem and the risk of suffering from ED. Regarding the relationship between certain personality traits and the risk of ED, the results of the research by ^{Gutiérrez et al. (2015)} should be highlighted, where a significant association with perfectionism is reflected. This finding is consistent with what has been published in the scientific literature (^{Pamies & Quiles, 2014}).

The scientific literature provides evidence that the family plays an important role in the risk of children and adolescents developing an ED (^{Mensi et al., 2022}; ^{Stillar et al., 2023}). Thus, the results of the research by ^{Canals et al. (2009)} show that certain cognitive and behavioral dimensions of parents have a long-term influence on their children's risk of developing an ED. On the other hand, the results of the research by ^{Frieiro et al. (2021)} show that families in which the family relationship is rated as "not very good" have a higher risk of adolescents developing an ED. These data are consistent with the results of other research carried out in which it is concluded that, when the relationships and family dynamics are complex, and rigid or very strict dynamics occur, these may have an effect on the development of psychopathological symptoms in children/adolescents (^{Cerniglia et al., 2017}). Along the same lines, a better attachment to the maternal figure predicts a lower risk of developing ED in both boys and girls (^{Cortés-García et al., 2019}). These findings are consistent with the systematic review by ^{Jewell et al. (2016)}, where they conclude that insecure attachment to the mother is consistent as a risk factor in the development of EDs in adolescence.

Regarding the sociocultural risk factors, several studies (^{Beato-Fernández et al., 2007}; ^{Cabaco et al., 2021}; ^{Cortés-García et al., 2019}) show that socialization problems predict the risk of eating disorders. Thus, ^{Amaya-Hernández et al. (2017)} consider that this relationship may be mediated by the relevance that the peer group takes on during adolescence, constituting itself as referents of socially acceptable roles and behaviors. On the other hand, in reference to sociocultural influences, the results of the research included in the systematic review show significant relationships between the risk of developing an ED and the following factors: the consumption of social networks and media (^{Mora et al., 2022}); the influence of advertising and the aesthetic ideal of thinness (^{Babio et al., 2009}; ^{Espinoza et al., 2010}); and the internalization of the standard of beauty (^{Gutiérrez et al., 2015}).

The results obtained in this systematic review should be considered taking into account a series of limitations: firstly, the studies included refer to adolescents aged between 12 and 18 years living in Spain, so they cannot be extrapolated to other types of population. Similarly, only articles with a cross-sectional, experimental, and/or quasi-experimental research design were included, and studies published in Spanish or English. Consequently, research that did not meet these criteria was not taken into account. Likewise, the time limitation set in the eligibility criteria (2007-2022) involves a restriction in the comprehension of the subject studied, which transcends this time range and there is extensive scientific literature prior to the date established. Finally, no books, book chapters, editorials, manuals, doctoral theses, or conferences were taken into account. This decision directly affects the results of the systematic review, as it leaves a potentially relevant body of scientific literature out of the analysis.

Regarding the practical implications of the present systematic review, it is crucial to continue advancing in the study of risk factors and triggers of EDs (^{Nebot, 2017}). ^{Striegel-Moore and Bulik (2007)} point out four reasons why it is essential to study risk factors in EDs: studying causal mechanisms helps us to understand why certain people develop an ED and others do not, which in turn helps to reduce stigma in patients; studies on risk factors are a very valuable source of information for the revision of current classification systems, which are based only on observed symptom and sign clusters; it allows us to improve the design and implementation of treatments; and it facilitates the identification of high-risk groups on which to perform preventive interventions, as well as to design the content of these interventions.

In short, the systematic review of the scientific literature suggests that EDs have a complex, multifactorial etiology, and we have not yet achieved a full understanding of them. So far multiple evidence suggests that there is a certain genetic predisposition as well as environmental variables that influence the risk of developing an ED. Thus, it can be specified that the risk of developing an ED is mediated by biological, psychological, family, and sociocultural risk variables, as reflected and supported by the results of the present systematic review. The paucity of research that focuses on sociocultural influences in relation to the risk of developing an ED is striking. Therefore, a possible future line of research would be to analyze in greater depth the relationship between current sociocultural influences (especially the use of social networks) and the risk of developing an ED in adolescence.