Sex differences in the influence of toxoplasmosis on stress and perceived anxiety: Evidence for the stress-coping hypothesis

Abstract

Life-long infection with Toxoplasma, which affects 30% of the human population, has specific behavioral effects. The stress-coping hypothesis explains why the toxoplasmosis-associated behavioral changes go in opposite directions in men and women. It suggests that toxoplasmosis impairs the health of humans, which results in chronic stress. Men and women are known to cope with stress in opposite ways. The first presumption of the hypothesis, impaired health, was confirmed in many studies. The second, higher level of stress, was tested only rarely. Levels of stress and anxiety, measured with the Perceived Stress Scale, and the State-Trait Anxiety Inventory X-2, respectively, were compared in a population of 614 Toxoplasma-free and 162 Toxoplasma-infected subjects. Higher stress was detected in the infected men, but not women. We also found that physical health had a positive rather than negative effect on stress when mental health is controlled, which seems to contradict the prediction of the stress-coping hypothesis. No differences were found in the anxiety of infected and noninfected subjects. Subjects who have objective reasons for stress (those with worse physical health) are less stressed than those without such reasons.