Olfactory perception and hedonic assessment of odor in major depressive disorder

Objective: The aim of this study was to investigate whether there is a difference in olfactory perception between patients with major depressive disorder and healthy controls. We also investigated the relation between the anhedonia level and the hedonic ratings of odors. The relation between cognitive functions and odor tests was investigated. Method: 16 patients who were admitted to the Psychiatry Clinic of Dokuz Eylül Universtiy Hospital, diagnosed as major depressive disorder and 11 healty volunteers showing similar features in terms of age and sex were included in this study. The Hamilton Depression Rating Scale was used to measure the depression levels of the participants and the TEPS Anhedonia Scale was used to measure the anhedonia levels. Cognitive functions were determined with Addenbrook Cognitive Assessment Battery. Odor perception was evaluated with Sniffin' Sticks Test and evoked potential obtained with the olfactometer. Results: As a result of the comparison between depression patients and healthy controls, it was observed that the threshold (p= 0,000), discrimination (p= 0,008) and total odor scores (p= 0,000) of SST battery were significantly lower in the patients. According to the olfactometer findings, the amplitude and latency values obtained from the olfactory stimuli did not differ significantly between the patients and healthy controls (p>0,05). A significant difference was found between the patient and healthy controls between the total cognitive scores (p= 0,002), fluency (p= 0,002) and memory (p= 0,027) according to the Addenbrook Cognitive Assessment Battery. It was observed that the cognitive functions of the patients were significantly lower than the healthy controls. There was no correlation between cognitive functions and odor test scores (p> 0,05). There was no significant difference between patients and healthy controls in terms of hedonic ratings of odor (p> 0,005). There was no relation between hedonic ratings and anhedonia levels (p> 0,005). Conclusion: The olfactor dysfunction was observed as a result of psychopyhsical tests. We detected that the there was no significant difference between groups in terms of hedonic evaluation of odors and there was no relation between hedonic evaluation of odors and anhedonia levels. We also found that there was no relation between odor tests and cognitive functions. Our results should be repeated with the larger sample. Key Words: Depression, Sniffin' Sticks, chemosensory event related potentials, cognition, anhedonia.