More than an association: Latent toxoplasmosis might provoke a local oxidative stress that triggers the development of bipolar disorder

Abstract

Introduction:Toxoplasma gondii, a common parasitic infection, has a special affinity to the brain. It has a lifelong existence without an apparent clinical disease. While the etiology of bipolar disorder (BD) remains unclear, epidemiological studies suggest a role for infections. Central nervous system is particularly susceptible to oxidative stress (OS) because of its high metabolic rate and its low levels of antioxidant defenses. OS is a contributor to the initiation and progression of many neurological illnesses. OS injury is a constantly and compelling finding associated with BD and toxoplasmosis.Aim:This cross-sectional study has investigated a possible role of toxoplasma-induced OS in the development of BD.Methods:Healthy controls and BD patients were examined for anti-Toxoplasma immunoglobulin-G (IgG) and two protein (3-nitrotyrosine) and DNA (8-hydroxy-2’ deoxyguanosine [8-OHdG]) OS markers.Results:Toxoplasma positivity was higher (40%) among BD patients compared to controls (12%). Significantly higher levels of anti-Toxoplasma IgG were detected in BD patients compared to controls. Nitrotyrosine (796.7 ± 106.28) and especially 8-OHdG (20.31 ± 8.38) were significantly higher among toxo-positive BD compared to toxo-negative BD (675.97 ± 144.19 and 7.44 ± 2.86) and healthy controls (464.02 ± 134.6 and 4.17 ± 1.43).Conclusion:These findings might indicate a role for Toxoplasma infection in the development of BD, possibly through creating a highly oxidative brain environment.

A Case–Control Seroprevalence Study on the Association Between Toxoplasma gondii Infection and Bipolar Disorder

“…Other studies have reported a higher seroprevalence of T. gondii infection in patients suffering from bipolar disorder than in control subjects. These findings have been reported in Saudi Arabia (19), France (20, 32), the United States (22), and Ethiopia (17). In a meta-analysis of 50 studies about the association of seroprevalence of T. gondii infection and psychiatric disorders, researchers found a significant OR with IgG antibodies in bipolar disorder (13).…”

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

“…Findings of this report suggest that re-exposure to the parasite Grande et al, 2017), as has been suggested for schizophrenia (Sutterland et al, 2015). Furthermore, the potential of latent toxoplasmosis to provoke the development of bipolar disorder has been suggested (Afifi et al, 2018). The present study showed that both depression and anxiety were more likely to occur in patients with toxoplasmosis than in those without, whereas varying results have been found in the literature.…”

“…Findings of this report suggest that re-exposure to the parasite could modify the individual's immune response and reactivate latent toxoplasmosis (Del Grande et al ., 2017), as has been suggested for schizophrenia (Sutterland et al ., 2015). Furthermore, the potential of latent toxoplasmosis to provoke the development of bipolar disorder has been suggested (Afifi et al ., 2018).…”

Neurological and Neurobehavioral Disorders Associated with Toxoplasma gondii Infection in Humans

“…It has been contemplated that latent T. gondii may trigger CNS oxidative stress, leading to immune-inflammatory processes that could promote or resemble CNS changes seen in bipolar disorder [ 82 – 84 ]. In studies conducted by Pearce et al and Hamdani et al, it was found that patients seropositive for T. gondii infection were approximately 2.3- and 2.7-folds more likely to have a history of bipolar disorder type I with manic and depressive symptoms than respondents who tested negative for the T. gondii antibody [ 85 , 86 ].…”