Impulsive and aggressive traits and increased peripheral inflammatory status as psychobiological substrates of homicide behavior in schizophrenia

Background and objectives

An association between inflammation and psychopathological domains of psychotic disorders is widely acknowledged; however, the involvement of inflammatory processes in the underlying pathophysiology of violent behavior in schizophrenia is yet to be elucidated. In this study, we aimed to address the differences in impulsive and aggressive traits as well as C-reactive protein (CRP) to albumin ratio (CAR) as a marker of inflammation between schizophrenia patients with a history of homicide and those without any history of interpersonal violence or criminal background.

Methods

The study population consisted of 80 male DSM-5 schizophrenia patients who were classified into two groups: homicidal (n=40) and non-violent (n=40). Impulsive and aggressive traits were evaluated with Barratt Impulsivity Scale-11 (BIS-11), and the Buss-Warren Aggression Questionnaire (BWAQ), respectively. For the calculation of CAR, the CRP and albumin levels were obtained from the file records of routine blood screenings performed in the month before the patients were included in the study.

Results

When adjusted for age, all subscale scores of the BIS-11 as well as BWAQ Total, Physical and Hostility scores were significantly higher in the homicidal group than in the control group. CRP and CAR were significantly higher, and albumin was significantly lower in the homicidal patients than the controls when adjusted for age, body-mass index and smoking status. Univariate and stepwise multivariate regression models indicated that BIS-11 Non-planning, BWAQ Total, BWAQ Hostility and CAR were independent predictors of belonging to the homicidal patient group, after stepwise adjustment for all potential confounders.

Conclusions

Our findings suggest that certain impulsive and aggressive traits as well as CAR, as a proxy marker of peripheral inflammation, may contribute towards homicidal tendencies and may predict a specific predisposition towards lethal violence in schizophrenia. The study highlights inflammation as a potential biological correlate of a specific behavioral phenotype (homicide) in schizophrenia.