Overrated hedonic judgment of odors in patients with schizophrenia

The odor identification ability and its hedonic judgment in patients with schizophrenia were evaluated in the study. The association between olfactory performance and negative symptoms and β-endorphin concentration was also analyzed.

Study groups consisted of 23 patients with negative symptoms (PN) and 25 without predominant negative symptoms (PP) and 21 healthy individuals. The University of Pennsylvania Smell Identification Test, odor hedonic evaluation, and plasma concentrations of β-endorphin assay in all participants were performed.

PN perceived the poorer olfactory identification; nevertheless, they evaluated unpleasant odors as more pleasant than PP and controls. Beta-endorphin concentration was significantly higher among PN than in other study groups. No association was observed between β-endorphin and odors identification and odor hedonic judgment among all study groups.

There is potential relationship between increased β-endorphin concentration and severity of negative symptoms. Patients with predominant negative symptoms tend to evaluate odors as significantly more pleasant. Individuals with this subtype of schizophrenia might present specific, altered pattern of smell identification and hedonic judgment. Presumably, β-endorphin has no direct influence on olfactory identification performance and hedonic judgment in schizophrenia.