Depression, Positive Symptoms of Psychosis, and Suicidal Ideation Among Adults Diagnosed with Schizophrenia: A Secondary Analysis of Data from the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) Using Structural Equation Modeling

Background/Purpose: Suicide is the leading cause of death among adults diagnosed with schizophrenia with risk estimates over eight times greater as compared to the general population.  While symptoms of depression are consistently supported factors involved in suicidal ideation and attempt, findings on the role of positive symptoms of psychosis have been mixed with limited understandings of how hallucinations and delusions relate to suicide risk.  High suicide rates have received attention in the literature to date, yet, behavioral evidence-based treatments are lacking as suicide continues to be a major public health problem.  Thus, we need to increase understandings of the factors involved in suicidal ideation and attempt within this vulnerable population as a first step towards ultimately developing suicide prevention-focused interventions.  Accordingly, this study aims to empirically test how symptoms of depression and positive symptoms of psychosis (i.e. hallucinations and delusions) relate to suicidal ideation.

Methods:  Data were obtained from the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE), a randomized controlled trial of antipsychotic effectiveness among a sample of adults diagnosed with schizophrenia (n= 1,460).  The outcome of suicidal ideation was measured post baseline by the Calgary Depression Scale (CDRS).  Symptoms of depression were measured by the CDRS and hallucinations and delusions were both measured by the Positive and Negative Syndrome Scale (PANSS), all at baseline.  The data were analyzed using Structural Equation Modeling (SEM) with AMOS 21.0 using a maximum likelihood algorithm.

Results:  The SEM model yielded good model fit by both global (chi square, CFI, standardized RMR, RMSEA) and focused (standardized residuals and modification indices) fit indices.  It was found that both hallucinations and delusions distinctly predicted suicidal ideation independent of depression but not when entered jointly in the same linear equation.  A latent variable model that focused on the common variance of hallucinations and delusions (represented as a latent positive symptoms of psychosis variable with hallucinations and delusions as indicators) was predictive of suicidal ideation over and above depression.  Both path coefficients for positive symptoms (latent) and depression were statistically significant (p<.05).  For every one unit increase in positive symptoms of psychosis (i.e. hallucinations and delusions), suicidal ideation was found to increase, on average, by .04 units (p < 0.05).  For every one unit increase in symptoms of depression, suicidal ideation was found, on average, to increase by .25 units (p < 0.05).  Symptoms of depression, hallucinations, and delusions accounted for approximately 13% of the variance in suicidal ideation.

Conclusions and Implications:  Symptoms of depression and positive symptoms of psychosis (i.e. hallucinations and delusions) are independently associated with suicidal ideation among adults diagnosed with schizophrenia.  White it has been consistently demonstrated that symptoms of depression predict suicidal ideation, the present study provides support for the relationship between positive symptoms of psychosis, specifically hallucinations and delusions, and suicidal ideation.  Future prospective longitudinal study designs are needed to further increase understandings of the roles that hallucinations, delusions, and additional symptoms of schizophrenia play in both suicidal ideation and attempt to ultimately inform evidence-based interventions aiming to reduce suicidal death.