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Introduction

Latent toxoplasmosis, affecting approximately one-third of people worldwide, was once thought to be asymptomatic. However, studies in the last three decades have revealed that it can cause significant psychological and behavioral changes in humans. The observation that the behavioral impacts of toxoplasmosis manifest in opposite directions in men and women has led to the development of the Stress-Coping Hypothesis. This hypothesis posits that health degradation from toxoplasmosis results in chronic stress, with gender-specific coping strategies explaining the divergent behavioral responses observed between men and women.

Methods

This study, conducted on 1,768 individuals who had previously been tested for toxoplasmosis or borreliosis, sought to examine this hypothesis through a survey that included the Perceived Stress Scale and the State-Trait Anxiety Inventory.

Results

Confirmed poorer health, higher stress, and anxiety levels amongToxoplasma-infected participants. Path analysis showed that toxoplasmosis directly negatively impacts physical health, which in turn directly increases stress and anxiety among infected individuals, thereby negatively affecting cognitive performance. This pattern was not seen with borreliosis, serving as a negative control, underscoring the unique impact of toxoplasmosis on human physical health, well-being, and cognition.

Conclusions

Our findings strongly suggest that the cognitive impairments associated with toxoplasmosis are primarily side effects of chronic stress resulting from the compromised health of infected individuals.

Key Points

Chronic stress mediates the negative effects of toxoplasmosis on cognition, stemming from the impaired health of infected individuals.

This effect was not observed with the negative control, borreliosis.

Our results support the side effects hypothesis and contradict the parasite manipulation hypothesis.