Exposure to common infections and risk of suicide and self-harm: a longitudinal general population study

The Role of Inflammation in Depression and Beyond: A Primer for Clinicians

PURPOSE OF REVIEW

We evaluate available evidence for the role of inflammation in depression. We reappraise literature involving systemic inflammation, neuroinflammation and neurotransmission and their association with depression. We review the connection between depression, autoimmunity and infectious diseases. We revise anti-inflammatory treatments used in depression.

RECENT FINDINGS

Peripheral inflammatory markers are present in a subset of patients with depression and can alter common neurotransmitters in this population but there is no clear causality between depression and systemic inflammation. Infectious conditions and autoimmune illnesses do not have a clear correlation with depression. Certain medications have positive evidence as adjunctive treatments in depression but studies are heterogenic, hence they are sparsely used in clinical settings. The current evidence does not fully support inflammation, infections or autoimmunity as possible etiologies of depression. The available studies have numerous confounders that obscure the findings. Anti-inflammatory agents may have potential for treatment of depression, but further research is needed to clarify their usefulness in routine clinical practice.

Impact of Toxoplasma gondii and Human Microbiome on Suicidal Behavior: A Systematic Review

BACKGROUND

Suicide remains a persistent global health challenge, resisting widespread prevention efforts. According to previous findings, toxoplasmosis is particularly associated with altered decision making, which could lead to risk-taking behavior, thereby increasing the likelihood for suicidal behavior (SB). In addition, discussion about the role of microbiome in psychiatric disorders has emerged lately, which also makes it relevant to investigate its role in the context of SB. Therefore, two systematic reviews are integrated in this paper, and the existing knowledge is comprehensively summarized regarding the association between microbial pathogens and SB.

METHODS

We conducted a systematic search with keywords including SB and Toxoplasma gondii (Suicid* AND Toxoplasm*) and microbiome (Suicid* AND Microbiome AND Microbiota) throughout PubMed and Scopus to retrieve related studies up to 9 November 2023, identifying 24 eligible records. The subjects of the included studies had to have fulfilled the criteria of an SB disorder as defined by DSM-5, and death cases needed to have been defined as suicide.

RESULTS

Most studies reported significant association between toxoplasmosis and SB, suggesting a higher likelihood of SB in the infected population. Regarding the microbiome, only very few studies investigated an association between SB and alterations in the microbiome. Based on six included studies, there were some indications of a link between changes in the microbiome and SB.

CONCLUSION

The cognitive aspects of decision making in T. gondii-infected individuals with SB should be further investigated to unravel the underlying mechanisms. Further sufficiently powered studies are needed to establish a link between SB and alterations in the microbiome.

Anti-Toxoplasma gondii Antibodies in European Residents: A Systematic Review and Meta-Analysis of Studies Published between 2000 and 2020

Toxoplasmosis has a major impact on animal and public health. Information regarding the seroprevalence of human Toxoplasma gondii infections from a European perspective has not yet been compiled to date. Thus, the present review summarized available resident data from the period 2000-2020. The overall seroprevalence of anti-T. gondii IgG was 32.1%, with great variability between countries (n = 30). The subgroup analysis identified different pooled prevalence data depending on the geographic area (p < 0.0001), target population (p = 0.0147), and serological diagnosis assays used (p = 0.0059). A high heterogeneity (I2 = 100%, p < 0.001; Q = 3.5e+05, d.f. = 135, p < 0.001) and degree of publication bias (Egger's test = 6.14, p < 0.001) were observed among the 134 studies considered. The occurrence of anti-T. gondii IgM, which was reported in 64.7% of studies, reached a pooled seroprevalence of 0.6%. In addition, among the eight main risk factors identified, "contact with soil", "consumption of undercooked beef", and "intake of unwashed vegetables" were the most significantly associated with infections. The fact that one-third of the European population has been exposed to T. gondii justifies extra efforts to harmonize surveillance systems and develop additional risk-factor analyses based on detailed source attribution assessment.

Cytomegalovirus antibodies are associated with mood disorders, suicide, markers of neuroinflammation, and microglia activation in postmortem brain samples

Cytomegalovirus (CMV) is a common, neurotrophic herpesvirus that can be reactivated by inflammation and cause central nervous system disease. We hypothesize that CMV may contribute to the neuroinflammation that underlies some psychiatric disorders by (1) exacerbating inflammation through the induction of anti-viral immune responses, and (2) translating peripheral inflammation into neuroinflammation. We investigated whether the presence of anti-CMV antibodies in blood were associated with mental illness, suicide, neuroinflammation, and microglial density in the dorsolateral prefrontal cortex (DLPFC) in postmortem samples. Data (n = 114 with schizophrenia; n = 78 with bipolar disorder; n = 87 with depression; n = 85 controls) were obtained from the Stanley Medical Research Institute. DLPFC gene expression data from a subset of 82 samples were categorized into "high" (n = 30), and "low" (n = 52) inflammation groups based on a recursive two-step cluster analysis using expression data for four inflammation-related genes. Measurements of the ratio of non-ramified to ramified microglia, a proxy of microglial activation, were available for a subset of 49 samples. All analyses controlled for age, sex, and ethnicity, as well as postmortem interval, and pH for gene expression and microglial outcomes. CMV seropositivity significantly increased the odds of a mood disorder diagnosis (bipolar disorder: OR = 2.45; major depression: OR = 3.70) and among the psychiatric samples, of suicide (OR = 2.09). Samples in the upper tercile of anti-CMV antibody titers were more likely to be members of the "high" inflammation group (OR = 4.41, an effect driven by schizophrenia and bipolar disorder samples). CMV positive samples also showed an increased ratio of non-ramified to ramified microglia in layer I of the DLPFC (Cohen's d = 0.81) as well as a non-significant increase in this ratio for the DLPFC as a whole (d = 0.56). The results raise the possibility that the reactivation of CMV contributes to the neuroinflammation that underlies some cases of psychiatric disorders.

Is human cytomegalovirus a potential risk factor for mood disorders? A systematic review and meta-analysis

Mood disorders are among the common mental disorders worldwide. Because of the persistence of cytomegalovirus (CMV) in the body and nervous system, this virus can be activated when the immune system is weakened and continues to exert its destructive effects throughout life. This study aimed to investigate the seroprevalence and association of human cytomegalovirus with mood disorders. Eligible articles were extracted using online international databases Science Direct, Medline, Web of Science, Scopus, and Google Scholar between 2000 and 2023. After quality assessment and specific inclusion and exclusion criteria, a total of eight eligible articles were included in the meta-analysis. Our finding showed that the seropositivity of CMV in mood disorders was 51.6% (95% CI; 42.8-60.4). There were statistical differences between mood disorders and control groups regarding the seropositivity of CMV 1.327% (95% CI; 13.27-10.45). The results of the publication bias using the Egger test confirmed no publication bias in each sub-group. The results of this meta-analysis study demonstrated that CMV infection might have associations with the incidence of mood disorders. Furthermore, we found that there were statistical differences between mood disorders and control groups regarding the seropositivity of CMV.

SARS-CoV-2 Infection and the Risk of Suicidal and Self-Harm Thoughts and Behaviour: A Systematic Review

OBJECTIVE

The COVID-19 pandemic has had a complex impact on risks of suicide and non-fatal self-harm worldwide with some evidence of increased risk in specific populations including women, young people, and people from ethnic minority backgrounds. This review aims to systematically address whether SARS-CoV-2 infection and/or COVID-19 disease confer elevated risk directly.

METHOD

As part of a larger Living Systematic Review examining self-harm and suicide during the pandemic, automated daily searches using a broad list of keywords were performed on a comprehensive set of databases with data from relevant articles published between January 1, 2020 and July 18, 2021. Eligibility criteria for our present review included studies investigating suicide and/or self-harm in people infected with SARS-CoV-2 with or without manifestations of COVID-19 disease with a comparator group who did not have infection or disease. Suicidal and self-harm thoughts and behaviour (STBs) were outcomes of interest. Studies were excluded if they reported data for people who only had potential infection/disease without a confirmed exposure, clinical/molecular diagnosis or self-report of a positive SARS-CoV-2 test result. Studies of news reports, treatment studies, and ecological studies examining rates of both SARS-CoV-2 infections and suicide/self-harm rates across a region were also excluded.

RESULTS

We identified 12 studies examining STBs in nine distinct samples of people with SARS-CoV-2. These studies, which investigated STBs in the general population and in subpopulations, including healthcare workers, generally found positive associations between SARS-CoV-2 infection and/or COVID-19 disease and subsequent suicidal/self-harm thoughts and suicidal/self-harm behaviour.

CONCLUSIONS

This review identified some evidence that infection with SARS-CoV-2 and/or COVID-19 disease may be associated with increased risks for suicidal and self-harm thoughts and behaviours but a causal link cannot be inferred. Further research with longer follow-up periods is required to confirm these findings and to establish whether these associations are causal.

Prevalence and Predictors of Toxoplasma gondii Infection in Psychiatric Inpatients in Fars Province, Southern Iran

BACKGROUND

Psychiatric patients are at increased risk of exposure to Toxoplasma gondii infection, which may be linked to their living facilities and behaviors. Limited knowledge on the prevalence of T. gondii infection and its associated risk factors in psychiatric patients are available to the international medical communities. Thus, the aim of the current study was to assess seroprevalence of T. gondii and its associated risk factors in psychiatric inpatients in Fars Province, southern Iran.

METHODS

This cross-sectional study was carried out on psychiatric patients hospitalized in Ibn Sina Hospital affiliated to Shiraz University of Medical Sciences, Fars Province, southern Iran, March to July 2021. Blood samples were collected from 318 psychiatric patients and assessed for the detection of IgG against T. gondii using enzyme-linked immunosorbent assay (ELISA). Moreover, structured questionnaires were completed for the participants at the time of sampling. Logistic regression analysis was used to assess possible associations between the latent toxoplasmosis and the variables.

RESULTS

The overall seroprevalence of anti-T. gondii IgG in psychiatric inpatients was 22.3% (71/318; 95% CI = 17.9-27.3). Multivariate analyses revealed that age > 30 years [adjusted odds ratio (AOR) = 2.24, 95% CI = 1.10-4.60, p = 0.03], contact with cats (AOR = 2.52, 95% CI = 1.14-5.58, p = 0.03), raw vegetable consumption (AOR = 3.65, 95% CI = 1.74-7.65, p = 0.001), raw/undercooked meat consumption (AOR = 4.30, 95% CI = 1.47-12.63, p = 0.008), suicide attempt (AOR = 3.77, 95% CI = 1.58-8.97, p = 0.003) and cigarette smoking history (AOR = 0.38, 95% CI = 0.17-0.83, p = 0.02) were independent risk factors for T. gondii infection.

CONCLUSION

The current results demonstrated that contact with cats, raw vegetable consumption and raw/undercooked meat consumption were independent risk factors for T. gondii seropositivity. Moreover, the current study showed significant associations between seropositivity of T. gondii and suicide attempts as well as negative associations between seropositivity of T. gondii and cigarette smoking in psychiatric inpatients using multivariate logistic regression.

Association between Suicide and Toxoplasma gondii Seropositivity

This study aimed to determine the association between suicide and Toxoplasma gondii (T. gondii) seropositivity. Serum samples of 89 decedents who committed suicide (cases) and 58 decedents who did not commit suicide (controls) were tested for anti-T. gondii IgG and IgM antibodies using enzyme-linked immunosorbent assays. Anti-T. gondii IgM antibodies were further detected by enzyme-linked fluorescence assay (ELFA). A total of 8 (9.0%) of the 89 cases and 6 (10.3%) of the 58 controls were positive for anti-T. gondii IgG antibodies (OR: 0.85; 95% CI: 0.28-2.60; p = 0.78). Anti-T. gondii IgG levels were higher than 150 IU/mL in two (2.2%) cases and in five (8.6%) controls (OR: 0.24; 95% CI: 0.04-1.30; p = 0.11). Anti-T. gondii IgM antibodies were not found in any case or control using the enzyme immunoassay and were found in only one (1.7%) control using ELFA (p = 0.39). Rates of IgG seropositivity and high levels of anti-T. gondii antibodies were similar in cases and in controls regardless of their sex or age groups. The results do not support an association between T. gondii seropositivity and suicide. However, the statistical power of the test was low. Further research is necessary to confirm this lack of association.

Raised C-reactive protein in medication overdose: A report of two cases

Studies have been coming out focusing on the biological markers of suicide. Here, we present two cases with raised C-reactive protein who were admitted after attempts of suicide by overdose. There is a need to study the neuro-immuno-endocrinal changes in suicide systematically that will give insight into the biological underpinning.