The notion of sex differences in odor perception was first reported over one hundred years ago. In general, women outperform men in odor identification and discrimination. When compared to men, women also demonstrate either higher sensitivity toward odors or rate them as more intense. Reports on sex differences regarding the hedonic valence of odorants are mixed, and differences in pleasantness ratings seem to be dependent on the type of odor. Furthermore, the social relevance of the odor seems to be important when investigating sex differences in odor perception.
Although behavioral studies seem to support that sex differences in olfaction exist, evidence of sex differences in the processing of odors in the peripheral and central nervous systems is scarce and contradictory. For pure odorants (odors with little or no trigeminal percept) it is known that women express larger amplitudes in olfactory event related potentials than men when smelling an odor. So far, we have, among other things, discovered that men and women process both pure trigeminal stimulation and the so-called bimodal odors (odors that activate the trigeminal as well as the olfactory nerve) differently in terms of cortical activation but there are no substantial differences when it comes to behavioral measures.
Why this difference in processing exists is still unknown. We are currently investigating more extensively the underlying neuronal substrates of these sex-differentiated responses to the various odor classes, i.e. unimodal (olfactory or trigeminal), bimodal or endogenous, by means of behavioral and neuroimaging (fMRI) studies.