Effects of latent toxoplasmosis on olfactory functions of men and women

Abstract

The prevalence of toxoplasmosis is higher in schizophrenics than in the general population. It has been suggested that certain symptoms of schizophrenia, including changes in olfactory functions, are in fact symptoms of toxoplasmosis that can be easily detected in schizophrenics only due to the increased prevalence of toxoplasmosis in this population. Schizophrenics have impaired identification of odors and lower sensitivity of odor detection. Here we searched for differences in olfactory functions between 62 infected and 61 noninfected non-schizophrenic subjects. The infected men scored better in the standard odor-identification test. The infected women rated all smells as more intensive while the infected men rated nearly all smells as less intensive. Infected women rated the pleasantness of the smell of undiluted cat urine as higher than the non-infected women and the opposite was true for the men (the opposite direction shifts in men and women were described earlier for highly diluted cat urine). Toxoplasmosis had no effect on the rated pleasantness of the smell of other stimuli. Our results suggest that latent toxoplasmosis is associated with changes in the olfactory functions in humans; however, the observed changes differ from those observed in schizophrenics.\n\nKey findingsO_LIInfected men but not women show better odor identification ability than the non-infected controls.\nC_LIO_LIThe infected women rated all smells as more and men as less intensive than the controls.\nC_LIO_LIThe infected women rated smell of cat urine as more and men as less pleasurable than the controls.\nC_LIO_LIToxoplasmosis had no effect on the rated pleasantness of the smell of other stimuli.\nC_LIO_LIWe found no new evidence for the toxoplasmosis hypothesis of schizophrenia.\nC_LI