Discriminating Depression, Physical and Social Anhedonia by Neurotransmitter Related Challenge Tests

The aim of this study was to investigate, if anhedonia, a salient component of depression, shows similar response patterns to neurotransmitter challenge tests as depression, and if the two questionnaire based components Physical (PA) and Social (SA) Anhedonia can be discriminated by differences in drug related size and time of cortisol responses elicited by the specific serotonin (5HT) and noradrenaline (NA) reuptake inhibitors citalopram and reboxetine and prolactin responses to the dopamine (DA) agonist bromocriptine orally applied to 36 male volunteers in a double blind balanced cross-over design. Analyses of variance applied to placebo corrected hormone responses revealed that low and late DA responses were characteristics of global Depression and of Physical Anhedonia, and that low DA responses were associated with high NA responses in PA, and with low 5-HT responses in SA. These patterns were explained by differences in transmitter production and receptor sensitivities and proved to be suitable to discriminate PA from SA and from global depression by analysing neurochemical response patterns rather than single means of variables.