Suicidal ideation in Chinese adults with schizophrenia: associations with neurocognitive function and empathy

Schizophrenia (SZ) is a serious mental disorder with a high suicide rate [1, 2]. Suicide risk can be assessed based on a multi-stage continuum (suicidal ideation, suicide plan, suicide attempted, and completed suicide [1, 3]). Suicidal ideation, at one end of the continuum, is the basis for the prediction of suicide and suicide prevention among patients with SZ [4]. Meta-analyses have shown that the lifetime risk of suicide for patients with SZ is 4.9% [5], and the lifetime prevalence of suicidal ideation among patients with SZ is 34.5% (95% CI: 28.2 − 40.9%) [1]. Suicide is considered to be one of the leading causes of premature death in patients with SZ [6]. Further, a recent study indicated that the suicide rate among young people with SZ has risen [7].

Many published studies have explored the risk of suicide among patients with SZ, and various risk factors have been found to be associated with suicidality in patients with SZ. These factors include demographic variables (such as male gender, younger age, and higher intelligence quotient), clinical characteristics (such as history of attempted suicide and poor adherence to treatment), and various other variables (such as hopelessness) [7]. In addition, neurocognitive function [8] and social cognition [9, 10] are reported to be risk factors for suicide, and their relationships with suicide have been widely explored in recent years. However, the reported risk factors for suicide among patients with SZ are often inconsistent. Therefore, more research is needed.

Nonsocial (also referred to as neurocognitive) and social cognitive impairments are among the core features of SZ. These impairments have a significant impact on treatment, prognosis, and functional outcomes for patients with SZ [11, 12]. Neurocognition and social cognition are two domains of cognition; neurocognition is a basic function of the central nervous system. To date, studies of patients with SZ have identified various neurocognitive deficits, including significant deficits in attention, executive function, learning, information processing, and memory [13]. However, findings on the association between suicide risk and cognitive impairment in SZ have been inconsistent. Some studies [14‐16] have reported that impaired neurocognition in patients with SZ is a risk factor for suicide, while others have reported a positive relationship between suicidal risk and improved cognitive function [17‐19], or no association between the two variables [20, 21]. Neurocognitive decline is often associated with aging [22], so the current study focused on young adults aged 18–44 years.

The relationship between social cognition and suicidal ideation has also been of great interest to researchers. Social cognition refers to a range of mental processes based on social interactions, including the perception, interpretation, and reaction to the intentions, personalities, and behaviors of others [23]. In particular, the relationship between interpersonal dysfunction and suicide is receiving increasing attention [24, 25]. The interpersonal theory of suicide suggests that frustrated attributions, perceived burdens, and the acquisition of suicidal competence lead to suicide [26]. Perceptions of failure and pitfalls (encompassing the perceptions of failure and no way forward or escape) have been found to be associated with suicidal ideation in SZ [27]. In other studies, lower scores on the Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT) [28], lower scores on the false belief task [29], and negative attribution bias and reactivity to more negative stimuli [9] were all associated with suicidal ideation in SZ patients. However, few studies have assessed the interpersonal aspects of social cognition related to suicidal ideation in SZ.

Empathy is an important element of social cognition and involves the integration of several social processes [30]. Empathy is the ability to understand and respond to the emotional experiences of others [31, 32]. It is a form of interpersonal support and plays an important role in building positive relationships and promoting cooperative behavior [33, 34]. Empathy includes both other-oriented empathy and self-oriented empathy [35]. Other-oriented empathy is the ability to experience and understand the feelings of others; it induces altruistic motivation to help others while distancing oneself from the situation. Other-oriented empathy can be measured with the Perspective Taking (PT) and Empathic Concern (EC) subscales of the Interpersonal Reactivity Index (IRI). Ego-oriented empathy is when an individual lacks a buffering distance and can become overwhelmed by exposure to others' distress. This can be measured by the Personal Distress (PD) and Fantasy (FS) subscales of the IRI. With self-direction, feelings of personal distress may evoke an egocentric motivation (to keep the individual in psychological distress) to alleviate the discomfort of exposing oneself to the distress of others [36, 37]. Some studies suggest that a decreased ability to recognize certain social emotions can impair one’s ability to interact socially, which may increase the risk of suicide [38]. In addition, the perceived sense of burden noted in interpersonal theories of suicide is associated with suicide risk, and the nature of this belief requires consideration of others, which may be associated with higher levels of empathy [26, 37]. While empathy is a core topic in social cognitive neuroscience research [39], it has received less attention in studies of patients with SZ. The available studies have not reached a consensus conclusion regarding the relationship between empathy and suicide in patients with SZ [37, 38]. In addition, to date, no published studies have examined the relationships between suicidal ideation and the two domains of cognition in schizophrenia patients. This study addresses this gap by exploring the relationships between suicidal ideation and both neurocognition and empathy.

Therefore, in this study, a cross-sectional design was employed to explore the factors associated with suicidal ideation in Chinese adults with SZ. This study focused on the relationships between suicidal ideation and both empathy and neurocognition. It was hypothesized that (1) certain demographic and clinical variables would be risk factors for suicidal ideation; (2) there would be correlations between suicidal ideation and both neurocognitive function and empathy in SZ patients.

In total, 301 patients with SZ spectrum disorders participated in this study. The mean age of the participants was 33.93 (SD = 6.37) years. The sample comprised 183 men (60.8%) and 62 patients with a family history of schizophrenia (20.6%). Moreover, 82 patients (27.2%) reported suicidal ideation in the last week or when they were most depressed.

This study attempted to combine three important topics of interest (suicidal ideation, neurocognitive function, and empathy) in Chinese adults with SZ. In this study, the prevalence of suicidal ideation (27.2%) among Chinese adults with SZ was similar to that reported among patients with SZ in China (25.8%) [49], but lower than the global set of lifetime prevalence of SI mentioned in another meta-analysis (34.5%, 95% CI: 28.2 − 40.9%) [1]. The reported rates of suicidal ideation among people with SZ vary widely. The reasons for these differences in the prevalence of suicidal ideation include different demographic characteristics of the patients, different illness stages, and various comorbidities [50]. Therefore, caution should be exercised when directly comparing the findings of the current study with those of other studies.

The current study did not find a relationship between the RBANS score and suicidal ideation among patients with SZ. This is similar to the results of previous studies [20, 21], and suggests that suicidal ideation among patients with SZ might not be related to neurocognitive function. However, the results of previous studies are inconsistent, and some studies [14‐16] have reported that impaired neurocognition in patients with SZ is a risk factor for suicide while others suggest that the risk of suicide in patients with SZ increases with improved cognitive function [17‐19]. Thus, given that the reported relationship between suicidal ideation and neurocognitive in patients with SZ is inconsistent, further prospective studies with larger samples are needed. The results of the current study were consistent with previous studies. Female patients with SZ were found to have lower RBANS scores than males [51], suggesting more neurocognitive impairment in females. Further, the RBANS Total Score and its subscales were negatively associated with PANSS Positive Symptoms, Negative Symptoms, General Psychopathology, and Total Score. There is one possible explanation for this negative correlation. Generally speaking, patients with SZ who take antipsychotic drugs tend to achieve remission of psychotic symptoms and a decrease in PANSS scale scores. However, cognitive deficits usually improve less with time and treatment [52, 53].

Interestingly, the results of the current study indicated that empathy, especially the IRI-Personal Distress subscale score, was higher in patients with suicidal ideation, as compared to those without suicidal ideation. Further, the results of the binary logistic stepwise regression analysis confirmed the relationship between suicidal ideation and the IRI-Personal Distress subscale. This result is consistent with a study of previous suicide attempts among Chinese patients with SZ [54], where suicide attempters were found to experience greater personal distress compared to those who did not attempt suicide. It is possible that people with SZ who score higher on personal distress have higher levels of anxiety and discomfort, which adversely impacts their interpersonal and social support, further contributing to suicidal ideation. Some studies have reported significant positive associations between personal distress subscale scores and negative affect, poor emotion regulation [55], and depressive symptoms [56], and a negative association with personal quality of life [57]. These are also risk factors for suicide [7, 58, 59]. Thus, it can be speculated that personal distress may also indirectly influence suicidal ideation through these risk factors.

In addition to psychosocial factors, neurobiological studies have found a positive correlation between IRI-Personal Distress subscale scores and blood oxygen level-dependent activities in the right temporal pole that are related to social behavior and functioning [60, 61]. Another study reported that psychiatric patients who died of suicide had a greater density of von Economo neurons in the anterior cingulate cortex, as compared to patients who died from other causes [62]. The paracingulate, anterior and posterior cingulate, and amygdala are closely related to empathy [34]. Therefore, it is possible that the positive relationship between IRI-Personal Distress and suicide ideation is related to changes in brain structures such as the anterior cingulate cortex. In addition, in the No Suicide Ideation group, the IRI-PT, EC, and Total Score were negatively correlated with the PANSS Negative Symptoms score, General Psychopathology score, and Total score. The severity of clinical symptoms may be a factor in predicting empathy in patients with SZ [63].

The results of this study also indicated that higher PANSS-General Psychopathology scores were associated with increased suicidal ideation in patients with SZ. This is consistent with previous studies which have found that general psychopathology symptoms are correlated with high suicide risk [64, 65]. Further, impulsivity is positively correlated with the PANSS-General Psychopathology score, and impulsivity is associated with suicide in patients with SZ [66]. However, some studies have not found a significant association between general psychopathology and suicide risk [67]. These varied results may be due to sample differences, such as differences in ethnicity or disease progression. Studies employing a longitudinal design with a larger sample are much needed to clarify these inconsistencies. Further, the current study found that the PANSS-General Psychopathology Symptoms score played a partial mediating role in the relationship between personal distress and suicidal ideation. This may be due to the similar concept and pattern of "anxiety and discomfort" in both the "personal distress" aspect of empathy [44] and the "general psychopathology symptoms" of the PANSS [46]. Thus, this mediating effect may be due to the inclusion of a common component. More studies are needed to verify these preliminary findings.

Additionally, high suicide attempts was found to be associated with increased suicidal ideation in people with SZ, similar to a previous study [68]. Suicide is a continuous process, and more suicide attempts may lead to more suicides [69]. Of interest, the results of the moderating effects show that this relationship weakened with increases in the RBANS-Visuospatial, Language, Attention, and IRI-PD scores. This suggests that higher neurocognitive function and empathy may effectively reduce the incidence of suicidal ideation associated with suicide attempts. The inclusion of neurocognition and empathy as moderator variables in this study provides a new perspective, with the findings suggesting that improving the RBANS-Visuospatial, Language, Attention, and IRI-PD scores of patients with SZ who have made suicide attempts is a possible means to reduce suicidal ideation. Nonetheless, this preliminary finding should be verified in future studies.

Previous cross-sectional and longitudinal studies of the relationship between neurocognition and social cognition have found that these two variables are related but distinct factors, and improving neurocognitive impairments and social cognition impairments requires different approaches [23, 70]. This study aimed to explore neurocognition and empathy as influential factors in suicidal ideation among patients with SZ. The results of this study provide relevant information about the role of personal distress within the concept of empathy and its association with suicidal ideation among patients with SZ. These findings offer a deeper understanding of the factors influencing suicidal ideation in patients with SZ, and this may inform the development of prevention and intervention approaches.

Several limitations of the present study should be noted. First, this cross-sectional study was not able to investigate the causal relationships between suicidal ideation and risk factors in Chinese adults with SZ. Thus, we cannot confirm whether there are direct causal relationships between suicide attempts and neurocognitive impairment, empathy, and clinical symptoms in patients with SZ. As such, the main findings of this study should be considered to be preliminary. Second, this study focused on patients with SZ and did not include a healthy control group. Thus, the results obtained in this study are limited. Future studies should include healthy controls as a comparison group. Third, the BSI—CV, which was used to assess suicidal ideation is a subjective scale. Nonetheless, it is widely used in clinical practice. Finally, unfortunately, family history of depression and family history of suicide were not included as variables in the current study, which may have limited the findings. These variables should be included in future studies of suicidal ideation among patients with SZ.

The results of this study indicate that the personal distress aspect of empathy, the severity of general psychopathological symptoms and suicide attempts are important predictors of suicidal ideation among Chinese adults with SZ. Moreover, the relationship between suicide attempts and suicide ideation was found to weaken with increases in empathy (personal distress) and neurocognitive function (visuospatial, language, and attention). This suggests that addressing neurocognitive function and empathy may play an important role in the prevention and treatment of suicidal ideation in patients with SZ. Future prospective studies with larger sample sizes are needed to validate the relationships between neurocognitive function, empathy, and suicidal ideation in patients with SZ.