The aim of this project was a two fold; one was to compare the olfactory identification ability in patients with schizophrenia or schizotypy with that of the patients with mood disorders as well as the normal subjects; the other was to assess any possible changes after treatment in olfactory identification ability in patients with schizophrenia.

The subjects of the study comprised 22 patients afflicted with schizophrenia and five with schizotypy (mean age of 41 years old), 28 patients with mood disorders (13 with major depressive and 14 with bipolar disorders with the mean age of 39 years old), and finally 27 normal subjects (mean age of 39 years old). All subjects were assessed initially and the patients with schizophrenia were assessed twice more three and six weeks after the commencement of treatment with the University of Pennsylvania Smell Identification Test (UPSIT). The data were analyzed by Kruskal- Wallis, Chi- square, Mann-Whitney, and Freedman tests.

A significant difference was found between patients with schizophrenia and schizotypy with normal subjects in olfactory identification ability. There was not any significant difference between other groups on this matter. No significant changes in olfactory identification ability were detected in schizophrenic patients after 3 and 6 weeks of treatment.

Deficit in olfactory identification ability of patients with schizophrenia spectrum disorders, and its persistence despite treatment is testimonial to its trait-like characteristic in such disorders.