Are bipolar disorder, major depression, and suicidality linked with Toxoplasma gondii? A seromolecular case-control study

ABSTRACT

Objective

The existence of predisposing effects of latent Toxoplasma gondii (T. gondii) infection in bipolar disorder (BD), major depression (MD), and even suicide attempt (SA) has long been debatable. This conjecture remains unclear because there is a lack of evidence regarding how T. gondii manipulates the brain and behavior.

Methods

We investigated the influence of T. gondii infection on BD and MD patients with or without SA compared to age-, sex-, and province-matched healthy controls (HCs) concurrently with serology and molecular-based evaluations. We prospectively assessed 147 volunteers with BD, 161 with MD, and 310 HCs.

Results

T. gondii seropositivity rates were 57.1% for BD, 29.2% for MD, 64.8% for SA, and 21.3% for HC. Binary logistic regression analyses revealed that T. gondii positive Immunoglobulin G (IgG) status may be a prominent tendentious agent for BD (OR = 3.52; 95% CI [2.19–5.80]; p < 0.001) and SA (OR = 17.17; 95% CI [8.12–36.28]; p < 0.001), but not for MD (OR = 1.21; 95% CI [0.74–1.99]; p = 0.45). Nevertheless, the T. gondii DNA ratios determined by polymerase chain reaction (PCR) were linked to BD and MD.

Conclusion

Our findings strongly support the burgeoning interest in the possibility that latent T. gondii infection may be relevant to the etiology of BD and SA, although this connection remains ambiguous.

KEYWORDS:

• Bipolar disorder
• major depression
• suicide
• Toxoplasma gondii
• PCR

Acknowledgments

We thank the Istanbul Aydin University Scientific Research Projects Unit for economical supports of our study. The authors report there are no competing interests to declare.

Declaration of financial/other relationships

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Additional information

Funding

This work was supported by The Istanbul Aydin University Scientific Research Projects Unit (2020/13).