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Depressiveness and Neuroticism in Bartonella Seropositive and Seronegative Subjects-Preregistered Case-Controls Study
Jaroslav Flegr1,2, Marek Preiss3, Pavla Balátová4
1Applied Neurosciences and Brain Imagination, National Institute of Mental Health, Klecany, Czechia.
Insights
This study investigated the link between Bartonella henselae infection and mental health. Bartonella seropositivity showed complex associations with depression and health, varying by Toxoplasma status and sex, suggesting other pathogens may explain cat-injury depression links.
Area of Science:
- Infectious Diseases
- Psychiatry
- Immunology
Background:
- Recent studies link cat-related injuries to depression and depressiveness.
- Cat-scratch disease, caused by Bartonella henselae, was hypothesized as a cause.
- Direct evidence for Bartonella's role in this association was lacking.
Purpose of the Study:
- To investigate the association between Bartonella henselae infection and mental/physical health.
- To examine correlations between Bartonella seropositivity, depressiveness, and self-reported health.
- To explore interactions between Bartonella, Toxoplasma seropositivity, and sex.
Main Methods:
- A preregistered case-control study involving 250 healthy subjects.
- Testing for anti-Toxoplasma IgG antibodies and anamnestic anti-Bartonella IgG antibodies.
- Measuring depressiveness using the Beck II inventory and neuroticism with the N-70 questionnaire.
Main Results:
- Bartonella seropositivity correlated positively with depression in Toxoplasma-seronegative men.
- Bartonella seropositivity correlated negatively with health in Toxoplasma-seronegative women.
- Complex interactions observed: Bartonella protected against Toxoplasma-associated neuroticism in men; Toxoplasma protected against Bartonella-associated health issues in women.
Conclusions:
- The association between cat-related injuries and depression may involve pathogens other than Bartonella henselae.
- Sex-specific and interactive effects of Bartonella and Toxoplasma infections on host phenotype are significant.
- Studying symbiont effects requires considering co-infections and host sex.
Abstract:
Several recent studies have demonstrated the association of cat-related injuries with major depression and with depressiveness in the general population. It was suggested that cat-scratch disease, the infection with the bacterium Bartonella henselae, can be responsible for the observed association. However, no direct evidence for the role of the Bartonella infection in this association has been published until now. In this preregistered case-controls study performed on 250 healthy subjects tested earlier for the presence of anti-Toxoplasma IgG antibodies, we searched for the positive association between presence of anamnestic anti-Bartonella IgG antibodies and depressiveness measured with Beck II inventory, depression subscale of neuroticism measured with N-70 questionnaire, and self-reported health problems. We found that that Bartonella seropositivity was positively correlated with Beck depression only in Toxoplasma-seronegative men and negatively correlated with health in Toxoplasma-seronegative women. Bartonella seropositivity expressed protective effects against Toxoplasma seropositivity-associated increased neuroticism in men while Toxoplasma-seropositivity expressed protective effects against Bartonella seropositivity-associated health problems in women. A comparison of the patterns of association of mental and physical health problems with Bartonella seropositivity and with reported cat-related injury suggests that different factor, possibly infection with different pathogen transmitted by cat related-injuries than the B. henselae, is responsible for the observed association of cat related-injuries with depressiveness and major depression. The existence of complex interactions between Bartonella seropositivity, Toxoplasma seropositivity, and sex also suggest that the effect of symbionts on the host's phenotype must by always studied in the context of other infections, and separately for men and women.
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