International Journal of Bipolar Disorders (Aug 2024)

Toxoplasma gondii IgG serointensity and cognitive function in bipolar disorder

  • Paul Rensch,
  • Teodor T. Postolache,
  • Nina Dalkner,
  • Tatjana Stross,
  • Niel Constantine,
  • Aline Dagdag,
  • Abhishek Wadhawan,
  • Farooq Mohyuddin,
  • Christopher A. Lowry,
  • Joshua Joseph,
  • Armin Birner,
  • Frederike T. Fellendorf,
  • Alexander Finner,
  • Melanie Lenger,
  • Alexander Maget,
  • Annamaria Painold,
  • Robert Queissner,
  • Franziska Schmiedhofer,
  • Stefan Smolle,
  • Adelina Tmava-Berisha,
  • Eva Z. Reininghaus

DOI
https://doi.org/10.1186/s40345-024-00353-8
Journal volume & issue
Vol. 12, no. 1
pp. 1 – 9

Abstract

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Abstract Background Alongside affective episodes, cognitive dysfunction is a core symptom of bipolar disorder. The intracellular parasite T. gondii has been positively associated with both, the diagnosis of bipolar disorder and poorer cognitive performance, across diagnostic boundaries. This study aims to investigate the association between T. gondii seropositivity, serointensity, and cognitive function in an euthymic sample of bipolar disorder. Methods A total of 76 participants with bipolar disorder in remission were tested for T. gondii-specific IgG and IgM antibodies and for cognitive performance using neuropsychological test battery. Cognitive parameters were categorized into three cognitive domains (attention and processing speed, verbal memory, and executive function). Statistical analysis of associations between continuous indicators of cognitive function as dependent variables in relationship to T. gondii, included multivariate analyses of co-variance for seropositivity, and partial correlations with IgG serointensity in IgG seropositives. All analyses were controlled for age and premorbid IQ. Results In seropositives (n = 27), verbal memory showed significant inverse partial correlations with IgG antibody levels (short delay free recall (r=–0.539, p = 0.005), long delay free recall (r=–0.423, p = 0.035), and immediate recall sum trial 1–5 (r=–0.399, p = 0.048)). Cognitive function did not differ between IgG seropositive and seronegative individuals in any of the cognitive domains (F (3,70) = 0.327, p = 0.806, n = 76). IgM positives (n = 7) were too few to be analyzed. Conclusions This investigation is the first to show an association between T. gondii IgG serointensity and memory function in a well-diagnosed bipolar disorder sample. It adds to the existing literature on associations between latent T. gondii infection and cognition in bipolar disorder, while further research is needed to confirm and expand our findings, eliminate potential sources of bias, and establish cause-effect relationships.

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