Too Depressed To Stop and Smell The Flowers – How Olfaction Is Rooted In Mental Health
Jenny Galvao

According to work by Ti-Fei Yuan of the Nanjing Normal University, there is a connection between chronic stress and deficiencies in the olfactory system in rats. This also proves to be true in humans as well; our sense of smell suffers if we are suffering from clinical depression.

This research has new potential implications for the future of treatment of depression; some brain stimulation, specifically by delivering medication to patients through the nose, could benefits patients who are plagued with depression.

“Odor based stimulation therapies have been shown to be effective in restoration of depression-caused memory loss; while deep brain stimulation or other non-invasive stimulations offer further direct and controlled olfactory system-targeted therapies,” the researchers explain.

In this study, the researchers analyzed previous findings to uncover a potential relationship between olfactory system and depression in humans. From this information and previously demonstrated insight, the researchers were able to draw several important conclusions.

Deficiencies in the olfactory system that can be observed in depressed patients are correlated with the severity of the symptoms of depression. Specifically, some previous neuroimaging studies found that reduced olfactory bulb volume was present in patients who were depressed, and in individuals who suffered from childhood maltreatment. Interestingly enough, the level of olfactory performance (specifically, detection acuity) was related to the current emotional status of the individual.

“In the future, it might be possible to combine deep brain stimulation or non-invasive brain stimulation methods to target the olfactory system. The olfactory bulb in human is relatively small (in percentage to the whole brain), compared to those of macrosmatic mammals,” the researchers propose.

Even with all this being said, future research should still examine this connection and potential treatments for depression related to the olfactory system. With a new target for therapies centred on the treatment of depression, perhaps this will create a new neurochemical goal for medications. Targeting olfaction in depression represents a novel way to tackle a difficult issue.

The changes in olfactory functions in certain chronic neurodegenerative diseases, like Parkinson’s disease, or Alzheimer’s disease, occur even before any symptoms of these diseases are actually shown. Many olfactory function assessments have been very useful in terms of developing a diagnosis of these diseases, as well determining a prognosis.
Chronic stress in animals, and depression in humans effect many aspects of daily life, even colouring our perceptual senses.
The link between odour detection, or olfaction and depression is a fairly new finding and more research is necessary before we can draw specific corrective measures. However, one key thing to understand is that our sense of smell, while we may feel that it is mostly benign in humans as a lesser sense, plays a very important role in our wellbeing. Just more evidence showing how important are our nonverbal channels.

Jenny Galvao_smallAbout the Author: Jenny Galvao is an undergraduate student at the University of Guelph studying psychology.





Yuan, Ti-Fei & Burton M. Slotnick. Roles of olfactory system dysfunction in depression. Progress in Neuro-Psychopharmacology & Biological Psychiatr. 2014., 54:26-30. doi: