The relation between depression, anhedonia and olfactory hedonic estimates--a pilot study in major depression.

Several studies investigating olfactory hedonics in major depression have brought conflicting results and an analysis of the relation between severity of depression, anhedonia and olfactory hedonics is still lacking. In order to investigate olfactory perception in different depressive states, we carried out olfactory testing during a depressive episode (n=37) and in a remitted state (n=17). As expected, patients were significantly less depressed (p<0.001) and less anhedonic (p=0.001) in the remitted state. A comparison of olfactory perception between age- and gender-matched patients and healthy volunteers (n=37) controlled for intrinsic olfactory deficits in major depression. In the depressive episode, we applied regression analyses to investigate the relation of olfactory hedonics, severity of depression and anhedonia. The Sniffin' Sticks Test extended by analogue rating scales for intensity and hedonic estimates was employed for olfactory testing. Depression severity was assessed with the Beck Depression Inventory (BDI), anhedonia with the Snaith-Hamilton-Pleasure-Scale (SHAPS). Odour identification ability was significantly reduced during the depressive state. In contrast, no significant differences in hedonic and intensity estimates could be found between the depressive and the remitted state and healthy controls. During the depressive episode, we found a significant relation only between anhedonia and olfactory hedonics. We concluded that anhedonia has potential impact on olfactory hedonics in major depression. Our results indicate the need for (1) confirmatory studies in severe melancholic depression and (2) investigation of the impact of anhedonia on olfactory hedonics in psychiatric diseases other than major depression.