Olfactory Training and Emotional State

Recent studies have shown that depression is characterized by a change in olfactory and emotional perception resulting in a decrease of the perception of positive stimuli (odors and facial expressions) and an increase in perception of negative stimuli (odors). Moreover, it has also been shown in healthy subjects that the presence of minor depressive symptoms leads to a decreasing of olfactory sensitivity. However, odor discrimination was not impaired in these subjects. This observation suggest the presence of a change in "targeted" olfactory perception in people with depressive symptoms without reporting major depression. In addition, studies in subjects with olfactory disorders (following respiratory tract infections or following Parkinson's disease) have shown an improvement in olfactory function after daily training with odors during 12 weeks. Therefore, the hypothesis is that an olfactory training could improve the overall olfactory functioning and the emotional perception of the subjects presenting minor depressive symptoms and of the depressed patients.

The main objective is to study the effect of daily olfactory training on the emotional state and emotional perception of the subject. The effect of the training will be evaluated using three types of evaluations: (1) a clinical evaluation and the psychometric scales, (2) the investigation of the olfactory function and (3) the study of the emotional perception.

The secondary objectives are:

• The identification of olfactory parameters and emotional valences associated with minor depressive symptoms.
• The study of the link between the subjective and objective emotional response on the one hand, and the link between olfactory function, emotional perception and emotional state on the other hand in depressed patients and in individuals with minor depressive symptoms.

Inclusion criteria

healthy subjects:

• Without psychiatric history
• QIDS scale score less than or equal to 15
• Affiliation to a social security system
• Able to give his written informed consent

Inclusion criteria

depressed patients:

• With a diagnosis of depressive episode characterized according to the DSM-5 criteria, confirmed by the Mini International Neuropsychiatric Interview (MINI)
• No argument for bipolar disorder or schizophrenia, confirmed by the MINI
• QIDS scale score greater than or equal to 16
• Follow-up in hospitalization and / or ambulatory consultation
• Without comorbidities (alcoholism, eating disorders ...)
• Affiliation to a social security system
• Able to give his written informed consent

Exclusion criteria

healthy subjects and depressed patients:

• Pathology or condition likely to modify their olfactory and / or taste perception
• Allergies with one or more odors, food allergies and / or known anosmias and ageusia
• Legal incapacity and / or circumstances rendering the person incapable of understanding the nature, objectives or consequences of the study