12. C-Reactive Protein and Suicide Attempts in Schizophrenia

Abstract

Background: The risk of suicide and suicide attempts is greatly elevated in schizophrenia. The causes of suicide in this population are not known with certainty. Studies indicate that infammatory processes may be linked with suicide behaviors. Elevated levels of C-Reactive Protein (CRP), a nonspe-cifc marker of infammation, have been found in many individuals with schizophrenia but the association with suicide attempts in this population has not been previously studied. Method(s): Patients with a diagnosis of schizophrenia or schizoaffective dis-order were assessed on the Columbia Suicide Severity Rating Scale and other clinical measures. Participants had a blood sample drawn from which was measured high sensitivity CRP and antibodies to infectious agents and food antigens. The associations between suicide variables and CRP and other immune markers were analyzed in logistic regression models employ-ing age, gender, race, and cigarette smoking as covariates. Odds ratios (ORs) associated with having a CRP level >=75th and 90th percentiles of a control group were calculated with the same covariates. Result(s): The 89 participants had a mean age of 38.6 years (SD 13.1) and were 73% male and 43% Caucasian; 24 were hospitalized and 30 had >1 assessment. A total of 42 (47%) had made a lifetime suicide attempt including 14 (16%) with >=2 attempts and 28 (31%) an attempt that required medical attention. A lifetime history of a suicide attempt was signifcantly correlated with a history of drug/alcohol abuse. There was not a signifcant association between a suicide attempt history and patient age at time of assessment, gender, race, clinical setting, cognitive score, current cigarette smoking, psychiatric symptom score, or type of medication received. A suicide attempt history was signifcant associated with elevation in the level of CRP (t = 2.56, P =.01). Having a level of CRP>=75th percentile and >=90th percentile of the control group was signifcantly associated with a suicide attempt history (OR 2.6 (95% CI 1.0, 6.8, P =.05) and OR 3.3 (95% CI 1.1, 9.9, P =.04) respectively). We did not fnd an association between a suicide attempt history and antibodies to food antigens or infectious agents. Conclusion(s): These results add to the growing body of literature about the role of infammation in schizophrenia. The identifcation of blood-based markers may provide for improved methods for the assessment and treatment and, ultimately, prevention of suicide attempts in individuals with schizophrenia.