Olfaction as a marker for depression in humans.
BACKGROUND
Animal studies show a strong link between the loss of olfactory function and depressive behavior. We analyzed, whether olfactory function is a marker for depression in humans. If so, reduced olfactory function can be expected in depression that improves to level of normality after successful antidepressive treatment.


METHODS
Twenty-seven female in-patients with depression were compared to 28 healthy age-matched women at the beginning and at the end of antidepressive therapy or at two visits, respectively. Olfactory function was assessed comprehensively including threshold, discrimination and identification testing, chemosensory event related potentials and olfactory functional magnetic resonance imaging.


RESULTS
At the beginning of psychotherapy the patients exhibited reduced olfactory discrimination, prolonged latencies of the event-related potential and reduced activation in secondary olfactory structures (thalamus, insula, and left middle orbitofrontal). After therapy, patients improved significantly in all of the parameters and consequently the differences between control group and patients vanished.


CONCLUSIONS
We conclude that olfaction is a marker for depression. However, the results are limited to a relatively selective sample of depressed women.
University of Dresden Medical School, Department of Psychosomatic Medicine and Psychotherapy, Fetscherstreet 74, 01307 Dresden, Germany; University of Gothenburg, Institute of Neuroscience and Physiology, Sahlgrenska University Hospital, Blå Stråket 5, 413 45 Gothenburg, Sweden. Electronic address: ilona.croy@neuro.gu.se.
Ilona
I
Croy
University of Dresden Medical School, Department of Psychosomatic Medicine and Psychotherapy, Fetscherstreet 74, 01307 Dresden, Germany.
Anja
A
Symmank
University of Dresden Medical School, Department of Psychosomatic Medicine and Psychotherapy, Fetscherstreet 74, 01307 Dresden, Germany.
Julia
J
Schellong
University of Dresden Medical School, Smell & Taste, Clinic, Deptartment of Otorhinolaryngology, Fetscherstreet 74, 01307 Dresden, Germany.
Cornelia
C
Hummel
University of Dresden Medical School, Department of Neuroradiology, Fetscherstreet 74, 01307 Dresden, Germany.
Johannes
J
Gerber
University of Dresden Medical School, Department of Psychosomatic Medicine and Psychotherapy, Fetscherstreet 74, 01307 Dresden, Germany.
Peter
P
Joraschky
University of Dresden Medical School, Smell & Taste, Clinic, Deptartment of Otorhinolaryngology, Fetscherstreet 74, 01307 Dresden, Germany.
Thomas
T
Hummel
D000328:Adult; D015415:Biomarkers; D016022:Case-Control Studies; D003863:Depression / Q000503:physiopathology* / Q000628:therapy*; D005260:Female; D006801:Humans; D008875:Middle Aged; D011613:Psychotherapy; D012903:Smell / Q000502:physiology*; D016896:Treatment Outcome; D055815:Young Adult
D015415:Biomarkers
Depression; ErP; Mood; Olfaction; Smell; fMRI