Olfactory anhedonia and negative olfactory alliesthesia in depressed patients

International audienceAnhedonia is a core symptom of depression. The present study aimed to investigate an "olfactory anhedonia" in depressed patients. Two odorants, one with pleasant (vanillin), and one with unpleasant (butyric acid) hedonic valence were evaluated by 30 depressed inpatients and 30 controls (healthy subjects, matched by age and gender). Participants explored the hedonic valence, intensity (discrimination) and perceived quality (identification) of 16 different stimuli (3 concentrations of odorants, their 9 combinations and one control containing distilled water). The hedonic perception showed that patients perceived unpleasant odorant significantly more unpleasant than controls. Concerning the intensity ratings, controls succeeded to discriminate between all concentrations of odorants, while patients discriminated between the different concentrations only for the unpleasant component. Regarding the identification task, patients perceived significantly more the unpleasant odorant than the pleasant one in an iso-intense unmixed odorants mixture, whereas controls perceived equally both odorants. These results support the notion of an olfactory perception impairment in depression. Further studies are needed to replicate these findings and to confirm the olfactory anhedonia or the olfactory negative alliesthesia in depressed patients