The impact of severity, course and duration of depression on olfactory function

Our results support the idea that depression is not uniformly related to olfactory impairment, but depends on duration and course of depression. The results generate the hypothesis that reduced olfactory identification is caused by cognitive impairment in recurrent depression. Moreover, the relation between olfactory threshold and depression might be partially caused by a cumulative damage of the olfactory epithelium after frequent respiratory diseases.