“Somatization” is the development or persistence of unexplained somatic distress [1]. Somatization represents a wide range of characteristics including pain from different areas of the body and pseudo-neurological or gastrointestinal symptoms [2,3]. The majority of somatization symptoms has been associated with difficulties in emotional regulation or childhood trauma [4]. Recently, it has been shown that emotional and cognitive factors, which could arise from childhood trauma, might mediate the causality from childhood trauma to somatization in adulthood [5,6].

Childhood trauma is caused by negative events that overwhelm an individual’s ability to cope, including neglect, abandonment, abuse, and accidents [7]. Childhood trauma may have long-term mental and physical health effects such as an increased risk of psychiatric disorders in adulthood [8]. Individuals exposed to multiple or severe traumatic events during childhood have been more likely to experience physical symptoms in adulthood [9-11]. In particular, childhood trauma may lead to somatization symptoms as well as rumination, cognitive reappraisal, and expressive suppression [12].

Rumination is considered a maladaptive coping strategy that exacerbates or maintains negative emotions [13,14]. Rumination’s critical feature is that the thoughts involved are self-related [15]. Rumination is regarded as a symptomatic characteristic of depression and is indicated as a vulnerability factor of depressive symptoms [16]. People with rumination frequently focus negatively on self-related stimuli or interpret external stimuli as negatively relating to themselves [17]. Several studies have reported rumination as a mediator between childhood trauma and somatization [17-19].

Cognitive reappraisal is an adaptive coping strategy that people can use to manage stress [20]. It may include reframing to a more positive perspective on stressful events and circumstances [21]. Cognitive reappraisal could help decrease somatization by encouraging individuals to perceive the issue from a constructive perspective [22]. Other studies have shown that the negative effects of childhood trauma on somatization symptoms are mediated by cognitive reappraisal [23]. Research has also suggested that cognitive reappraisal may lead to a reduction in physical symptoms associated with anxiety and stress [21].

Expressive suppression may constitute a central mechanism underlying emotion regulation difficulties following childhood trauma [24,25]. This strategy, characterized by attempts to inhibit the outward expression of emotions in specific contexts, can serve as a means of attenuating affective responses triggered by traumatic experiences [26]. However, excessive reliance on expressive suppression may hinder the effective processing of trauma-related negative emotions and obstruct adaptive coping strategies, thereby perpetuating heightened emotional distress [27]. In the short term, expressive suppression may function as an avoidance-oriented strategy to temporarily alleviate psychological pain; yet, over time, it is likely to contribute to sustained psychological distress and the emergence of associated somatic symptoms [25].

While the relationships between childhood trauma and somatization have been established, there is a lack of understanding of and evidence for the basic mechanisms. Furthermore, studies have investigated rumination, cognitive reappraisal, and expressive suppression separately. To our knowledge, these variables have not been analyzed together in regard to childhood trauma and somatization.

Therefore, this study used the generalized linear model (GLM) to analyze the relationships among childhood trauma, somatization, rumination, cognitive reappraisal, and expressive suppression in clinical patients diagnosed with depression and/or anxiety disorder. In particular, rumination, cognitive reappraisal, and expressive suppression were investigated as mediator factors of the association between childhood trauma and somatization. We hypothesize that adults with childhood trauma may have high levels of rumination and expressive suppression and may lack the capacity for cognitive reappraisal. Additionally, we predicted that these traits would affect somatization symptoms. Furthermore, we investigated whether subtypes of childhood trauma had differential impacts on somatization as mediated by rumination, cognitive reappraisal, and expressive suppression.

Table 1 shows the sociodemographic characteristics of the 125 participants. Of the total, 76.0% of respondents were female (mean age=39.26±13.79 years). Among participants, 40.0% were employed, 45.6% had graduated from college or above, and 32.8% were married. The mean K-CTQ score was 10.11±3.85, indicating a high level of childhood trauma in the study populations. The mean K-RRS score was 58.99±15.08, which indicates a high level of clinically significant rumination. The mean ERQ_C and ERQ_R scores were 4.12±1.31 and 4.16±1.32, respectively. The mean SCL-90-R_S score was 26.05±10.28, indicating high levels of reported somatization symptoms.

Table 2 presents the correlations between childhood trauma, rumination, cognitive reappraisal, expressive suppression, and somatization. Childhood trauma was positively correlated with rumination (r=0.380, p<0.01) and somatization (r=0.498, p<0.01) and negatively correlated with cognitive reappraisal (r=-0.249, p<0.01). However, childhood trauma was not significantly correlated with expressive suppression. Rumination was positively correlated with expressive suppression (r=0.204, p<0.05) and somatization (r=0.432, p<0.01) and negatively correlated with cognitive reappraisal (r=-0.341, p<0.01). Cognitive reappraisal was negatively correlated with somatization (r=-0.416, p<0.01) but was not significantly correlated with expressive suppression.

Table 3 lists the indirect effects in the model of childhood trauma and somatization mediated by rumination, cognitive reappraisal, and expressive suppression. The path coefficients from childhood trauma to rumination (β=0.374, p<0.001) and from rumination to somatization (β=0.169, p<0.001) were significant. The path coefficients from childhood trauma to cognitive reappraisal (β=-0.096, p<0.01) and from cognitive reappraisal to somatization (β=-2.150, p<0.001) were also significant. However, the path from childhood trauma to expressive suppression was not significant, though the direct path from expressive suppression to somatization was significant (β=1.285, p<0.001). The bootstrapping index of the indirect effect was not significant when expressive suppression was included as a mediating variable.

Table 4 illustrates the results of a multiple mediation analysis examining the indirect associations between childhood trauma and somatization through three psychological mediators: rumination, cognitive reappraisal, and expressive suppression. The mediation pathway via rumination was statistically significant, yielding an unstandardized indirect effect of 0.260 (standard error [SE]=0.110, z=2.63, p=0.009), with a 95% bias-corrected bootstrap confidence interval (CI) ranging from 0.066 to 0.454, and a standardized coefficient (β) of 0.098. Similarly, cognitive reappraisal demonstrated a significant mediating effect (estimate 0.180, SE=0.081, z=2.22, p=0.027), with a 95% CI of 0.021 to 0.338 and β=0.068. In contrast, the indirect effect via expressive suppression did not reach statistical significance (estimate=0.040, SE=0.038, z=1.04, p=0.298), and the CI encompassed zero (95% CI: -0.035 to 0.114; β=0.015). These findings suggest that rumination and cognitive reappraisal function as significant psychological mechanisms linking childhood trauma to somatic symptoms, whereas expressive suppression does not appear to play a mediating role in this context.

Table 5 shows the results of simple mediation models assessing the indirect and direct effects of childhood trauma on somatization through three mediators: rumination, cognitive reappraisal, and expressive suppression. When rumination was examined as a mediator, childhood trauma significantly predicted increased rumination (a=0.374, p<0.001), which in turn was positively associated with somatization (b=0.169, p<0.01), yielding a significant indirect effect of 0.265 (p<0.01). The direct effect of childhood trauma on somatization remained significant (c=1.325, p<0.001), indicating partial mediation. For cognitive reappraisal, childhood trauma negatively predicted the use of reappraisal strategies (a=-0.096, p<0.01), while greater cognitive reappraisal was strongly associated with reduced somatization (b=-2.150, p<0.001). The resulting indirect effect was statistically significant (0.207, p<0.05), with a significant residual direct effect (c=1.117, p<0.001), again supporting partial mediation. In contrast, expressive suppression did not serve as a significant mediator: the indirect effect (0.040) was not statistically significant, and both the a-path (a=0.048) and b-path (b=0.834) failed to reach significance. Nevertheless, the direct effect of childhood trauma on somatization remained significant in this model as well (c=1.285, p<0.001). Collectively, these findings suggest that rumination and cognitive reappraisal partially mediate the relationship between childhood trauma and somatic symptoms. In contrast, expressive suppression does not appear to play a significant intermediary role.

Table 6 reports the results of a multiple mediation analysis investigating whether specific subtypes of childhood trauma exert indirect effects on somatization through rumination, cognitive reappraisal, and expressive suppression. Notably, emotional abuse was the only subtype that demonstrated a significant indirect effect via rumination (estimate=0.159, SE=0.085, z=1.878, p=0.006), with a 95% bias-corrected bootstrap CI of 0.007 to 0.324 and β=0.086. Other trauma subtypes, including emotional neglect, physical abuse, physical neglect, and sexual abuse, did not exhibit significant indirect effects through any of the proposed mediators, as all CIs contained zero and corresponding p-values exceeded conventional thresholds. Additionally, none of the trauma subtypes showed significant indirect effects through expressive suppression, and the indirect paths through cognitive reappraisal were also nonsignificant across all subtypes. These results highlight the specific impact of emotional abuse on somatization symptoms, mediated by increased levels of rumination, while suggesting limited mediating roles for cognitive reappraisal and expressive suppression across other trauma subtypes.

Supplementary Table 1 demonstrates that childhood trauma is a significant predictor of somatization even after controlling for depression. Childhood trauma exhibited both direct and indirect effects on somatization after adjusting for depression, with statistically substantial mediation observed through rumination (β=0.217, p=0.017) and cognitive reappraisal (β=0.174, p=0.035), but not expressive suppression (p=0.583). The direct effect of childhood trauma on somatization remained significant (β=0.185, p=0.015). Among subtypes of childhood trauma, emotional abuse was linked to somatization via rumination (β=0.079, p=0.047). In contrast, other mediation pathways involving emotional neglect, physical abuse, physical neglect, and sexual abuse did not reach statistical significance (all p>0.05).

Figure 1 represents the associations among childhood trauma and somatization, as mediated by rumination, cognitive reappraisal, and expressive suppression.

The current study investigated whether depressive rumination, cognitive reappraisal, and expressive suppression mediate the effects of childhood trauma on somatization symptoms.

Our results found that childhood trauma was associated with somatization symptoms in the study sample. This finding is similar to earlier findings that childhood trauma affected somatization in patients with major depressive disorder [12]. These results were in accordance with studies that childhood trauma is key in the psychosocial and emotional development to adulthood [4,34]. Individuals with a history of childhood trauma indicated more frequent somatization or medically unexplained symptoms than non-traumatized individuals [35]. Accordingly, our study had shown that childhood trauma, such as emotional abuse or neglect, sexual abuse, and physical abuse, may lead to somatization symptoms in adulthood.

The current study showed significant indirect effects of childhood trauma on somatization as mediated by rumination and cognitive reappraisal. Our results support previous findings about the relationship between childhood trauma and poor mental health outcome as mediated by remination [36,37]. Rumination may be more common in adults who have been exposed to adverse childhood experiences [38,39]. Experience of childhood trauma often is not discussed or shared and can lead to a ruminative cognitive style. An increased level of ruminative response after childhood trauma can decrease the probability of resolving issues that could alleviate adverse effects [40]. Moreover, rumination could increase isolation and reduce social support; thus, it may lead to negative memories and somatization symptoms [41].

Many studies have reported negative correlations between childhood trauma and cognitive reappraisal ability, and many others have shown that lack of cognitive reappraisal ability has a mediating effect on the relationships between childhood trauma and various adult psychopathologies such as depression and anxiety [42,43]. According to Gross’s emotional regulation model, reappraisal may be adaptive and protective [44]. Reappraisal is an antecedent-focused emotion regulation strategy because it focuses on helping individuals reinterpret and better understand the nature and significance of a situation or stimulus and motivates actions at the early stage of the emotion-generation process. The aforementioned characteristics of reappraisal make it possible to effectively control improper emotional expression, improve a negative subjective emotional experience, and reduce the severity of emotional physiological response [45-47]. Therefore, it can be inferred that the lack of reappraisal ability leads to a state in which it is difficult to control emotional physiological responses, the persistence of which can appear as various somatic symptoms.

Importantly, these mediation effects of rumination and cognitive reappraisal persisted even after controlling for depressive symptoms. The supplemental analysis demonstrated that childhood trauma retained significant direct and indirect pathways to somatization, with rumination and cognitive reappraisal both emerging as robust mediators independent of depression. This finding suggests that the influence of trauma on somatization is not merely a byproduct of comorbid depressive symptomatology, but rather reflects trauma-specific cognitive and emotional processes. In particular, excessive rumination may maintain maladaptive self-focused thinking patterns, while deficient cognitive reappraisal may hinder adaptive reframing of distressing experiences. Together, these processes constitute parallel yet complementary mechanisms through which childhood trauma exerts long-lasting effects on somatic symptoms.

Meanwhile, our study found no significant effects of childhood trauma on somatization as mediated by expressive suppression. Over the years, many approaches, including psychoanalytic theory, have considered expressive suppression as a major psychological mechanism and cause of somatization [48]. Several clinical researchers have shown that individuals who have an impaired capacity for verbalization of emotions are vulnerable to somatization of emotional distress [49-51]. In this way, unverbalized psychological stress appears as physical symptoms. In addition, from the perspectives of classical psychoanalysis, emotions and fantasies related to repression of intrapsychic conflicts are central in contributing to somatic problems [52,53]. Although repression differs from expressive suppression in that it is an unconscious process, whereas expressive suppression is a conscious strategy, both share the common feature of inhibiting unpleasant emotions [26,54]. However, several empirical studies on the relationship between inhibiting emotions and somatization symptoms have reported inconsistent results. Some studies have reported that people who are unable to express uncomfortable emotions and tend to repress them often complain of physical symptoms [55]. However, other studies have reported no significant relationship between emotional expressive suppression and somatization symptoms [56,57].

Furthermore, in the context of childhood trauma, expressive suppression may not be the main psychological mechanism in the manifestation of somatization symptoms. In persons who have experienced childhood trauma, somatization symptoms may be trauma symptoms created by mechanisms such as hyper- or hypoarousal [58]. From this perspective, exposure to a trauma causes lasting physiological alternation in one’s reaction to aversive stimuli, which may lead to various somatization symptoms [58,59]. In this context, dissociation or rumination, rather than expressive suppression, may be central in the process of somatization in traumatized individuals [60,61]. Dissociation has properties similar to expressive suppression in terms of avoiding psychological pain but is a distinct concept. Future research should consider the effects of trauma-related psychopathology such as dissociation on somatization symptoms.

The current study also found that childhood trauma is related to somatization severity in adulthood. Regarding subtypes of childhood trauma, the indirect effect of rumination was only significant in the relationship between emotional abuse and somatization. Based on the results of previous studies, among the subtypes of childhood trauma, emotional abuse seems to have the greatest impact on mental health in adulthood. Repeated emotional abuse, particularly in the early years of life, can lead to unregulated arousal [62,63]. Such a state can result in various types of somatic symptoms related to hyper-arousal or hypo-arousal [62]. Furthermore, childhood emotional abuse involves enduring patterns of mistreatment, such as constant criticism, humiliation, rejection, or belittling by caregivers or authority figures during a person’s formative years [64]. Childhood emotional abuse can lead to internalized negative beliefs about oneself, low self-esteem, and difficulty regulating emotions [42,65]. In response to this distress, individuals may engage in rumination as a negative coping strategy. Rumination involves dwelling on negative emotions and experiences associated with the abuse, potentially intensifying one’s emotional responses [17,66]. The prolonged and intensified negative emotions resulting from rumination can contribute to somatization [67].

Other forms of childhood trauma appeared to be associated with somatization symptoms, but the indirect effects of rumination, cognitive reinterpretation, and expressive suppression were not significant. It is possible that neglect trauma, sexual abuse, and physical abuse may have contributed to somatization symptoms through different mechanisms. Future research will need to examine the various factors that mediate the relationship between childhood trauma and somatization symptoms.

Taken together, these findings suggest that various forms of psychological interventions that enhance cognitive restructuring and reduce ruminative responses may help reduce somatization symptoms in patients who have experienced childhood trauma. Therefore, the development of cognitive behavioral therapy protocols and interventions that focus more on fostering deficient cognitive restructuring skills and addressing excessive ruminative responses may be needed to help patients who report somatization symptoms after childhood trauma.

There are some limitations to this study. First, our study was cross-sectional in design. Future longitudinal studies of adverse childhood experiences are needed to demonstrate causal relationships. Second, assessments regarding such issues as childhood trauma, somatization, depressive rumination, cognitive reappraisal, and expressive suppression were based on self-reported questionnaires. It may be that participants with depression or anxiety symptoms distorted representations of their childhood traumatic memories. Thus, the interpretation of the results should be cautious. Third, other factors related to childhood trauma, such as the timing or length of the traumas and relationships with the perpetrators, were not evaluated. Such factors might also influence current symptom severity. In the future, longitudinal studies that track various psychological variables over time in children who have experienced childhood trauma into adulthood will be necessary to clarify causal relationships more precisely. This approach will make it possible to more clearly determine how factors such as the timing and duration of childhood trauma influence somatization symptoms and related mediators examined in the present study. Fourth, although the sample size was adequate for an exploratory mediation model, it may be insufficient to detect small indirect effects with high statistical power, particularly in a clinical sample. Therefore, the findings should be interpreted with caution, and replication with larger and more diverse samples is warranted.

Despite these limitations, this study offers important clinical insights by examining the indirect effects of key emotion regulation strategies-rumination, cognitive reappraisal, and expressive suppression-on the association between childhood trauma and somatization in a clinical sample of patients with depressive and anxiety disorders. Contrary to theoretical perspectives, including psychoanalytic accounts that link the suppression of unpleasant emotions to somatization, our findings suggest that reducing rumination and enhancing cognitive reappraisal may be more critical for symptom reduction. Accordingly, interventions targeting these cognitive processes, rather than focusing solely on emotional expression, may be more effective in clinical settings.

In conclusions, this study suggests significant evidence from clinical patients of the mediating role of depressive rumination and cognitive reappraisal between childhood trauma and somatization symptoms. Our findings suggest that rumination is a key element for outpatients who experienced childhood emotional abuse and currently present somatization symptoms. Thus, in clinical practice, interventions to reduce ruminative responses and foster cognitive reinterpretation may help reduce various forms of somatization in patients who have experienced childhood trauma.