Schizophrenia is recognized as a severe and complex mental disorder (1, 2) that is often associated with impairments in social cognitive (SC) function (3–5). Patients with schizophrenia may experience difficulties in accurately understanding the emotions, intentions, and social norms of others (6, 7). These issues frequently lead to conflicts and instances of aggressive behavior between patients with schizophrenia and their close caregivers, resulting in strained interpersonal relationships (8, 9). Consequently, these factors disrupt normal social interactions and significantly impact the individual’s quality of life and career development (10, 11).

The pathogenic mechanisms underlying schizophrenia are not yet fully elucidated. Besides genetic dispositions, previous research has focused on sociopsychological factors (5, 12). Among these factors, childhood trauma (CT) has been proposed as a potential risk factor for schizophrenia onset (13–15). This includes experiences such as physical abuse, emotional abuse, sexual abuse, physical neglect, and emotional neglect (14, 16, 17). These traumatic experiences may not only potentially heighten the risk of adolescents exhibiting psychotic symptoms (17–19) but also increase their vulnerability to the development of schizophrenia (20).

Furthermore, experiences of bullying during adolescence may serve as another potential factor in the onset of schizophrenia (12, 21). A study found that boys who frequently engage in bullying behaviors, or those who frequently find themselves the victims of such behaviors, are more susceptible to developing schizophrenia in early adulthood (22). This finding is further substantiated by a longitudinal investigation involving 4,720 participants, which concluded that regardless of whether one is a perpetrator or victim of bullying, experiencing bullying during adolescence increases the risk of developing mental disorders (23). This body of evidence points toward a discernable connection between bullying and mental illness, specifically schizophrenia.

The cognitive function of patients with schizophrenia is impaired, as established by previous research (3, 4, 24, 25). However, limited studies have implemented the threshold value of the Childhood Trauma Questionnaire-Short Form (CTQ) to differentiate patients with schizophrenia who have experienced childhood trauma from those who have not and to investigate potential differences in cognitive functioning between these two groups. This is particularly significant in the context of their social cognition function, which significantly impacts their quality of life and successful reintegration into society. Existing literature suggests that exposure to social adversity during childhood may contribute to the formation of negative internal working models, selective attention toward emotional stimuli and greater difficulties with emotional self-regulation (26). Moreover, studies have revealed that CT can affect an individual’s social cognitive functioning, particularly in terms of their intimate relationship with their mother (5). The presence of physical neglect significantly influences the intimacy between patients with schizophrenia and their parents, standing as the most potent predictor for their challenges in emotional recognition (5).

The purpose of the present study was to explore the effects of self-reported CT and bullying on the cognitive function of schizophrenia patients, with a focus on social cognition. The hypotheses formulated for this study were as follows (1): Patients with schizophrenia are likely to have endured more adversities during their early life - as quantified by the CTQ and the Bullying Scale for Adults (BSA) - in comparison to those without any such diagnosis (2); Experiencing adversities during early life could potentially impair cognitive function, with a particular impact on SC.

To the best of our knowledge, this is the first study in which the CTQ, BSA, and MCCB have been employed to examine the impact of early life adversity on cognitive functioning, particularly in the domain of SC, in patients with schizophrenia. The findings of the study have confirmed our hypothesis that, compared to healthy controls, patients with schizophrenia experience more early life adversity, including bullying. These early life adversities are associated with poorer cognitive functioning, especially SC, which has been considered to be closely related to quality of life and occupational development of the patients.

As hypothesized, patients with schizophrenia had significantly higher scores on the CTQ and BSA than healthy controls, which means that patients with schizophrenia experience more early life adversities. The study findings are in line with previous research studies. A meta-analysis of 36 studies (46) revealed that, compared to healthy controls, the odds ratio (OR) for CT in patients with schizophrenia was 2.78 (95% CI: 2.34-3.31). Specific forms of trauma showed an OR of 2.90 (95% CI: 1.71-4.92) for neglect, 3.40 (95% CI: 2.06-5.62) for emotional abuse, 2.95 (95% CI: 2.25-3.88) for physical abuse, and 2.38 (95% CI: 1.98-2.87) for sexual abuse. Another study (47) indicated that patients with schizophrenia had higher scores on measures of sexual abuse than healthy controls. According to a prospective cohort study (23) of 4720 children aged 8 to 11 years, children who reported bullying had a higher likelihood of developing a mental illness by age 18 than children who did not (OR=2.4, 95% CI: 1.6-3.4). A case‒control study (12) also found that schizophrenia patients were bullied twice as much as healthy controls. According to revictimization theory (48–50), individuals who experience childhood trauma may be more likely to become targets of bullying and attacks and are more likely to experience further trauma. A longitudinal study (51) validated this theory, as 213 (11.1%) out of 1915 young adults who experienced sexual abuse before adulthood reported experiencing sexual abuse again in adulthood.

SCZ-ct group was observed to have the lowest IQ scores among the three groups in the current study. This finding aligns with a 6-year follow-up study involving 1,119 patients with schizophrenia spectrum disorders. The study revealed that patients with schizophrenia spectrum disorders who had a history of childhood trauma exhibited the least progress in intellectual abilities, suggesting the lowest learning effect (52). Similar results were found in a study examining the impact of childhood trauma on intellectual functioning in patients with bipolar disorder, indicating that the presence of childhood trauma further impairs their intellectual abilities (53). This may be attributed to the negative effect of trauma on neural development, leading to alterations in brain structure and function (7, 54, 55).

In terms of SC, patients with schizophrenia have difficulty accurately understanding others’ emotions, intentions, and social signals when communicating with caregivers (5) or during social interactions. They may misunderstand others’ facial expressions, language, and nonverbal cues (6, 56), leading to poor communication and interpersonal tension. The results confirm our hypothesis that SC was significantly associated with childhood trauma, as indicated in the stepwise linear regression analyses. We found that the factors of “physical abuse” in CTQ and “emotional abuse” in BSA (bullying scales for adult) were significantly anti-correlated with social cognitive function (r = -0.271 and -0.265, respectively). In the multivariate regression, no specific type of trauma or bullying experience were identified to be independent predictors for social cognition, and the only contributor was the total score of CTQ (Beta=-0.582). This suggests that the social cognition impairments would better be explained by a cumulative effects of various kinds of childhood adversities.

Previous studies have shown that cognitive function is impaired in patients with schizophrenia (3, 4, 24, 25), with CT playing an important role in SC impairment in schizophrenia (5, 7, 26, 56–58). One study showed that schizophrenia patients had significantly lower scores in parental relationships and SC than healthy controls, with physical neglect being the strongest predictor of emotional recognition impairment. Good parental relationships were found to alleviate this emotional problem (5). Another survey involving 204 children aged 8-11 found that victims of bullying had difficulty in some moral judgment tasks (59), indicating that bullying has a negative impact on individuals’ SC. Furthermore, CT was found not only to affect the SC of schizophrenia patients but also to contribute to the cognitive impairment of bipolar disorder patients, specifically in working memory and executive function (60). A comprehensive review of 1,723 mood disorders and 797 healthy controls also confirmed that CT has a certain impact on the cognitive and executive functions of mood disorders (61).

Schizophrenia is a complex and severe mental disorder that involves various biological, psychological, social, and environmental factors (1, 2, 62–65), and CT increases the risk of developing this illness. Long-term and repeated exposure to negative environments, such as trauma and bullying, disrupts the balance of neurohormones (particularly glucocorticoids) (66), which can affect neuronal development and connectivity while altering epigenetic modifications (67). This process also impacts synaptic pruning during critical periods of early brain development (68, 69), as early life is a crucial period for individual brain development (53, 70, 71). Therefore, early-life adversities, including childhood trauma, disturb the balance of neurohormone secretion and lead to structural changes in the brain. These structural alterations can affect the cognitive functioning of patients with schizophrenia.

Notably, we found that the SC scores of SCZ-ct were significantly lower than those of SCZ-nct, while there was no significant difference in neural cognition dimensions (58, 72). It appears that CT independently contributes to the shaping of SC. Childhood is considered an important stage for both individual neural development and SC development (53, 70, 71, 73). During this period, the social environment in which children exist has a profound impact on their SC and behavioral patterns (74). According to Bowlby’s attachment theory (75), developing a secure attachment with a caregiver, especially one related to the mother, during childhood enables individuals to form a positive and secure “internal working model” in their interactions with others. This secure attachment relationship is an important prerequisite for successful social interactions. In contrast, experiencing adverse traumatic events during childhood, such as low levels of care and neglect, hinder the development of a secure attachment relationship, leading to difficulties in trusting others, exhibiting poor adaptability to the environment in adulthood (76), and even manifesting psychotic symptoms. Bowlby’s attachment theory (75) provides a cognitive-developmental framework for understanding the potential mechanisms by which early-life adversity may impact SC abilities later in life.

In addition to familial trauma, patients with schizophrenia are more susceptible to experiencing bullying during their early life. Both factors contribute significantly to the exacerbation of their social cognitive impairments. Our research enhances the understanding of the impact of early life adversity on cognitive functioning, specifically social cognitive function, in individuals with schizophrenia.

Moreover, the findings of this study offer valuable insights for the development of innovative psychological interventions. These interventions aim at alleviating the long-term repercussions of early life adversity for individuals with schizophrenia. This underscores not only the importance of childhood trauma experiences, which are currently considered during clinical assessments and treatment plans but also elevates the significance of bullying experiences in individuals with schizophrenia.

Therefore, to prevent and mitigate the lasting effects of childhood trauma and bullying on individual development and potential psychiatric disorders in individuals with schizophrenia, the development of new social-psychological intervention strategies is essential. These would facilitate their recovery and social reintegration.

The original contributions presented in the study are included in the article/ Supplementary Material , further inquiries can be directed to the corresponding authors.

The studies involving humans were approved by the Medical Ethics Committee of North China University of Science and Technology and the Ethics Committee of Beijing Anding Hospital, Capital Medical University. The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study.

XP: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Visualization, Writing – original draft, Writing – review & editing. W-PH: Writing – review & editing, Writing – original draft. Y-SD: Writing – review & editing, Writing – original draft. QW: Writing – review & editing, Data curation. FL: Writing – review & editing, Funding acquisition. SS: Writing – review & editing. C-CY: Writing – review & editing. X-JZ: Conceptualization, Funding acquisition, Project administration, Resources, Supervision, Writing – review & editing. F-CZ: Conceptualization, Funding acquisition, Project administration, Resources, Supervision, Writing – review & editing. C-YW: Conceptualization, Project administration, Resources, Supervision, Writing – review & editing.