Seasonality of Suicidal Behavior

A seasonal suicide peak in spring is highly replicated, but its specific cause is unknown. We reviewed the literature on suicide risk factors which can be associated with seasonal variation of suicide rates, assessing published articles from 1979 to 2011. Such risk factors include environmental determinants, including physical, chemical, and biological factors. We also summarized the influence of potential demographic and clinical characteristics such as age, gender, month of birth, socioeconomic status, methods of prior suicide attempt, and comorbid psychiatric and medical diseases. Comprehensive evaluation of risk factors which could be linked to the seasonal variation in suicide is important, not only to identify the major driving force for the seasonality of suicide, but also could lead to better suicide prevention in general

Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors

Background Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. Methods We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors. Results Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged. Conclusions Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.Peer reviewe

C-Reactive Protein Correlates with Negative Symptoms in Patients with Schizophrenia

Peripheral and CNS-localized inflammatory processes are hypothesized to contribute to the complex pathophysiology of schizophrenia. Elevated levels of the acute phase reactant C-reactive protein (CRP) have been observed in schizophrenia, yet relatively few studies have investigated the association between this inflammatory biomarker and psychotic symptoms in schizophrenia. This study is a pilot cross-sectional analysis investigating the relation of plasma CRP levels and the positive and negative symptoms of schizophrenia (the primary aim), assessed by the Positive and Negative Syndrome Scale (PANSS). A secondary analysis was also performed evaluating the potential association of CRP with cognitive function using the NIH Toolbox Cognitive Test Battery. After adjusting for age, sex, race, and body mass index, a positive correlation was observed between CRP and PANSS negative symptoms (rho = 0.37, p = 0.05). There was no correlation between plasma CRP and any of the NIH Toolbox measures of cognitive function in the unadjusted or adjusted analyses. Though limited by a relatively small sample size and the unavailability of longitudinal data, the correlation between CRP and psychopathology in this sample of patients supports a role for inflammation in the pathophysiology of schizophrenia

Plasma soluble P-selectin correlates with triglycerides and nitrite in overweight/obese patients with schizophrenia

Background: Soluble P-selectin (sP-selectin) is associated with risk factors for cardiovascular disease (CVD) but this association has not been evaluated in patients with schizophrenia. This study primarily evaluated the association of sP-selectin with plasma lipids and nitrite (NO2-) respectively in overweight/obese adults with schizophrenia

Toxoplasma gondii Immunoglobulin G Antibodies and Nonfatal Suicidal Self-Directed Violence

Objective: The primary aim was to relate Toxoplasma gondii seropositivity and serointensity to scores on the self-rated Suicide Assessment Scale (SUAS-S). Another aim was to reevaluate the previously reported positive association between T gondii serointensity and a history of nonfatal suicidal self-directed violence. Method: This cross-sectional, observational study compared T gondii serointensity and seropositivity in plasma from 54 adult suicide attempters (inpatients at Lund University Hospital, Lund, Sweden) and 30 adult control subjects (randomly selected from the municipal population register in Lund, Sweden) recruited between 2006 and 2010.The potential of patients and controls for self-directed violence was evaluated with the SUAS-S. Psychiatric diagnoses were made according to DSM-IV criteria. Plasma samples were tested for immunoglobulin G antibodies to T gondii, cytomegalovirus, and herpes simplex virus type 1. Data were analyzed using multivariable logistic regression to investigate the association between T gondii serointensity or seropositivity and a history of nonfatal suicidal self-directed violence; multivariable linear regression was used to explore the relationship between T gondii serointensify or seropositivity and the SUAS-S. Both regression models included sex, age, and body mass index as covariates. Results: Seropositivity of T gondii (adjusted odds ratio [OR]=7.12; 95% CI, 1.66-30.6; P=.008) and serointensity of T gondii (adjusted OR=2.01; 95% CI, 1.09-3.71; P=.03) were positively associated with a history of nonfatal suicidal self-directed violence. Seropositivity of T gondii was associated with higher SUAS-S scores, a relationship significant for the whole sample (P=.026), but not for suicide attempters only. No significant associations with other pathogens were identified. Conclusions: These results are consistent with previous reports on the association between T gondii infection and nonfatal suicidal self-directed violence. Confirming these results in future large longitudinal studies and including suicide as an outcome may lead to novel individualized approaches in suicide prevention. J Clin Psychiatry 2012;73 (8):1069-1076 (c) Copyright 2012 Physicians Postgraduate Press, Inc

Toxoplasma gondii, Suicidal Behavior, and Intermediate Phenotypes for Suicidal Behavior

Within the general literature on infections and suicidal behavior, studies on Toxoplasma gondii ( T. gondii ) occupy a central position. This is related to the parasite\u27s neurotropism, high prevalence of chronic infection, as well as specific and non-specific behavioral alterations in rodents that lead to increased risk taking, which are recapitulated in humans by T. gondii\u27s associations with suicidal behavior, as well as trait impulsivity and aggression, mental illness and traffic accidents. This paper is a detailed review of the associations between T. gondii serology and suicidal behavior, a field of study that started 15 years ago with our publication of associations between T. gondii IgG serology and suicidal behavior in persons with mood disorders. This “legacy” article presents, chronologically, our primary studies in individuals with mood disorders and schizophrenia in Germany, recent attempters in Sweden, and in a large cohort of mothers in Denmark. Then, it reviews findings from all three meta-analyses published to date, confirming our reported associations and overall consistent in effect size [ranging between 39 and 57% elevation of odds of suicide attempt in T. gondii immunoglobulin (IgG) positives]. Finally, the article introduces certain links between T. gondii and biomarkers previously associated with suicidal behavior (kynurenines, phenylalanine/tyrosine), intermediate phenotypes of suicidal behavior (impulsivity, aggression) and state-dependent suicide risk factors (hopelessness/dysphoria, sleep impairment). In sum, an abundance of evidence supports a positive link between suicide attempts (but not suicidal ideation) and T. gondii IgG (but not IgM) seropositivity and serointensity. Trait impulsivity and aggression, endophenotypes of suicidal behavior have also been positively associated with T. gondii seropositivity in both the psychiatrically healthy as well as in patients with Intermittent Explosive Disorder. Yet, causality has not been demonstrated. Thus, randomized interventional studies are necessary to advance causal inferences and, if causality is confirmed, to provide hope that an etiological treatment for a distinct subgroup of individuals at an increased risk for suicide could emerge