The associations of suicidal ideation with psychopathology and inflammatory cytokines in patients with chronic schizophrenia.

BACKGROUND

Suicidal ideation (SI) is common in patients with chronic schizophrenia, but the exact mechanisms underlying its development are unclear. Therefore, this study aimed to initially assess the prevalence of SI and to thoroughly explore the potential associations between SI and general demographic factors, psychopathological characteristics, and inflammatory cytokines in patients with chronic schizophrenia.

METHODS

From May to December 2018, 302 patients with chronic schizophrenia were included in this study. A self-administered questionnaire was used to collect general demographic data, and a series of scales were used to assess SI, psychotic symptoms, depression, insomnia, involuntary movements, extrapyramidal side effects, and akathisia symptoms, respectively. Additionally, plasma levels of inflammatory cytokines, including interleukin (IL)-1β, IL-6, IL-17 A and tumor necrosis factor-α (TNF-α) were measured. By logarithmic transformation with a base of 10, the values of Log IL-1β, Log IL-6, Log IL-17 A, and Log TNF-α were yielded. Among these, SI was designated as the dependent variable, with other psychopathological symptoms and inflammatory cytokines serving as independent variables, while general demographic factors were controlled for as potential confounders. Finally, multifactorial logistic stepwise regression analyses were performed to identify independent factors influencing SI in patients with chronic schizophrenia. Receiver operating characteristic (ROC) curve analyses were then used to assess the predictive value of each identified independent factor for SI.

RESULTS

The prevalence of SI (lifetime) and SI (last week) in patients with chronic schizophrenia was 36.4% and 8.0%, respectively. After controlling for general demographic factors such as age, Body Mass Index (BMI), and years of education, regression analyses showed that being female, Calgary Depression Scale (CDSS) score and Log IL-1β were independent correlates of patients' SI (lifetime), while chlorpromazine equivalents, Positive and Negative Syndrome Scale (PANSS) score, CDSS score and Log IL-6 were independent correlates of SI (last week). Additionally, ROC curve analyses showed that the combination of both CDSS score and Log IL-1β items demonstrated better discriminative ability of SI (lifetime). And the four-item combination of chlorpromazine equivalents, PANSS score, CDSS score and Log IL-6 was a better predictor of SI (last week).

CONCLUSION

There was higher overall risk of SI in patients with chronic schizophrenia. SI might be associated with psychotic symptoms, depression, insomnia, medication side effects, and increased levels of inflammatory cytokines. In clinical practice, doctors should take prompt preventive measures in patients combining suicidal risk factors.