brain sciences Review Depression, Olfaction, and Quality of Life: A Mutual Relationship Marion Rochet 1, Wissam El-Hage 1,2 ID , Sami Richa 3, François Kazour 1,4 ID and Boriana Atanasova 1,* ID 1 UMR 1253, iBrain, Université de Tours, Inserm, 37200 Tours, France;
[email protected] (M.R.);
[email protected] (W.E.-H.);
[email protected] (F.K.) 2 CHRU de Tours, Clinique Psychiatrique Universitaire, 37044 Tours, France 3 Department of Psychiatry, Faculty of Medicine, Saint-Joseph University, P.O. Box 17-5208, 11-5076 Beirut, Lebanon;
[email protected] 4 Psychiatric Hospital of the Cross, 60096 Jal Eddib, Lebanon * Correspondence:
[email protected]; Tel.: +33-2-47-36-73-05 Received: 13 April 2018; Accepted: 3 May 2018; Published: 4 May 2018 Abstract: Olfactory dysfunction has been well studied in depression. Common brain areas are involved in depression and in the olfactory process, suggesting that olfactory impairments may constitute potential markers of this disorder. Olfactory markers of depression can be either state (present only in symptomatic phases) or trait (persistent after symptomatic remission) markers. This study presents the etiology of depression, the anatomical links between olfaction and depression, and a literature review of different olfactory markers of depression. Several studies have also shown that olfactory impairment affects the quality of life and that olfactory disorders can affect daily life and may be lead to depression. Thus, this study discusses the links between olfactory processing, depression, and quality of life. Finally, olfaction is an innovative research field that may constitute a new therapeutic tool for the treatment of depression.