Is there any association between Toxoplasma gondii infection and depression? A systematic review and meta-analysis

Abstract

Background Toxoplasma gondii ( T . gondii ) is an obligate intracellular opportunistic parasite that is the causative agent of toxoplasmosis. This parasite accounts for mental disorders; however, the relationship between T . gondii infection and depressive disorder is unclear. Regarding this, the present systematic review and meta-analysis was conducted to investigate the scientific evidence regarding the potential association between major depression disorder (MDD) and Toxoplasma infection. Methods For the purpose of the study, the articles related to the subject of interest were systematically searched in seven electronic databases. Special attention was given to the studies examining T . gondii seropositivity level in depressed patients and controls. Results The search process resulted in the identification of a total of 30 publications meeting the inclusion criteria and published up to April 2018 for the systematic review. Furthermore, 29 studies met the inclusion criteria to be entered into meta-analysis. Our meta-analysis involved the review of cross-sectional studies including 1657 depressed patients and 19565 individuals as controls and case-control studies entailing 1311 depressed cases and 6015 controls without depression. 1582 depressed people participated in cross-sectional studies whose results were reported as odds ratio (OR). In addition, the total number of participants was 15068 in this type of studies. Statistical analysis indicated that the pooled OR of the risk of anti- T . gondii IgG antibody in depressed individuals in case-control and cross-sectional studies was 1.15 (95% confidence interval (CI): 0.95–1.39). Conclusions As the findings of the reviewed articles indicated, toxoplasmosis is not a risk factor for MDD. However, it is necessary to perform further research to clarify the detailed association between T . gondii and dysthymia or mild and moderate depression. Furthermore, it is recommended to better investigate the effect of antibody titers on the relationship between depression and T . gondii infection.

Association between exposure to toxoplasmosis and major psychiatric disorders: a systematic review

“…This review describes the main results of studies that evaluated the association between ET and major psychiatric disorders (schizophrenia, BD and MDD), using the criteria and diagnostic interviews summarized in the DSM-IV and later manuals. While there is consensus regarding the lack of association between ET and MDD, 48 there are conflicting findings regarding its association with schizophrenia and BD, since we observed heterogeneity of results. A plausible explanation is the above-mentioned strain hypothesis, 12 , 14 , 32 since different regional strains of T. gondii affect different populations and could mediate different neuropsychiatric effects.…”

Prevalence and Influencing Factors of Anxiety and Depression Symptoms in the First-Line Medical Staff Fighting Against COVID-19 in Gansu

“…The front-line medical staff will not only bear the work pressure of overload, but also face the huge risk of infection (2). Stress represents the main environmental risk factor for psychiatric illnesses, and in a long-term stress state, people can be more prone to depression or other mental disease (3), which will also increase the risk of infection (4)(5)(6). Therefore, it is necessary to investigate the psychological state of the first-line anti-epidemic medical staff and give them necessary psychological interventions if they have anxiety or depression.…”

Infection with Toxoplasma gondii increases the risk of psychiatric disorders in Taiwan: a nationwide population-based cohort study

“…A community-based study found that T. gondii seropositivity was associated with anxiety, but not depression (Markovitz et al ., 2015), and a cohort study indicated that toxoplasmosis was associated with anxiety (Flegr and Horáček, 2020). Two meta-analyses concluded that T. gondii infection was not associated with depression (Wang et al ., 2014; Nayeri Chegeni et al ., 2019). Notably, a Danish study found that T. gondii seropositivity was associated with moderate–severe depression, but not mild–severe (Bay-Richter et al ., 2019 a ; Nayeri Chegeni et al ., 2019); therefore, severity of depression may be one possible reason for conflicting relationships between T. gondii infection and depression reported in the literature.…”