Taste and odor: reactivity in depressive disorders, a multidisciplinary approach

Depressive patients often complain about dullness of taste of previously liked food items as well as of persistent bad taste. Taste and smell experience can be reflected by cognitive (psychophysical) indicators and also by reflectory (facial expressive) responses. In the present study 21 depressed, hospitalized patients and 16 control subjects were exposed to food-related gustatory and olfactory stimuli. Psychophysical and videotaped facial reactions were recorded from both groups. Analysis indicated that cognitive estimates of taste hedonics were similar for depressed and control groups; the former responded to sweet taste with a shorter-lasting facial reaction, involving markedly fewer facial features expressing enjoyment, than did controls. Aversive tastes, in contrast, triggered comparable facial expressive features of disgust in both groups. Facial reactions of depressed patients to acceptable and aversive olfactory stimuli were all significantly shorter and more muted than those of controls. Facial reflexes triggered by chemical cues are known to be controlled primarily by brainstem structures. Present findings suggest a possible influence of the profound anhedonia of severe depression on subcortical processes.