Odor Hedonic Capacity and Anhedonia in Schizophrenia and Unaffected First-Degree Relatives of Schizophrenia Patients

Abstract

There is increasing evidence that schizophrenia patients have difficulties in the hedonic appraisal of odors. In a prior study, we assessed olfactory hedonic perception birhinally and found that males with schizophrenia failed to attach the appropriate hedonic valence to a pleasant odor, despite correctly perceiving changes in odor intensity. Female patients, in contrast, exhibited normal responses. The current study extends this work by examining odor valence processing in unaffected first-degree relatives of schizophrenia patients, to determine the extent to which this abnormality may be genetically mediated. We also examine odor valence processing unirhinally, rather than birhinally, to probe possible lateralized differences in patients' hedonic processing deficits. Individuals with schizophrenia (n = 54), first-degree unaffected family members (n = 22), and demographically matched controls (n = 45) were administered the Suprathreshold Amyl Acetate Odor Intensity and Odor Pleasantness Rating Test. In contrast to family members and controls, both male and female schizophrenia probands underevaluated the hedonic characteristics of amyl acetate at lower concentrations and overevaluated its pleasantness at concentrations perceived as unpleasant by both controls and relatives. These patient-specific differences could not be explained by differences in smoking habit, medication use, or subjective ratings of odor intensity. However, they were associated with increased levels of anhedonia/asociality and negative symptomatology. Our findings suggest that both male and female schizophrenia patients have difficulties in the unirhinal appraisal of hedonic valence. Normal responses in unaffected first-degree relatives suggest that this is an environmentally, rather than genetically, mediated abnormality denoting negative symptomatology.