INSERM U930 ERL 3106, Université François Rabelais de Tours, Tours, France.
PLoS One. 2012;7(10):e46938. doi: 10.1371/journal.pone.0046938. Epub 2012 Oct 3.
Nowadays, depression is a major issue in public health. Because of the partial overlap between the brain structures involved in depression, olfaction and emotion, the study of olfactory function could be a relevant way to find specific cognitive markers of depression. This study aims at determining whether the olfactory impairments are state or trait markers of major depressive episode (MDE) through the study of the olfactory parameters involving the central olfactory pathway. In a pilot study, we evaluated prospectively 18 depressed patients during acute episodes of depression and 6 weeks after antidepressant treatment (escitalopram) against 54 healthy volunteers, matched by age, gender and smoking status. We investigated the participants' abilities to identify odors (single odors and in binary mixture), to evaluate and discriminate the odors' intensity, and determine the hedonic valence of odors. The results revealed an "olfactory anhedonia" expressed by decrease of hedonic score for high emotional odorant as potential state marker of MDE. Moreover, these patients experienced an "olfactory negative alliesthesia", during the odor intensity evaluation, and failed to identify correctly two odorants with opposite valences in a binary iso-mixture, which constitute potential trait markers of the disease. This study provides preliminary evidence for olfactory impairments associated with MDE (state marker) that are persistent after the clinical improvement of depressive symptoms (trait marker). These results could be explained by the chronicity of depression and/or by the impact of therapeutic means used (antidepressant treatment). They need to be confirmed particularly the ones obtained in complex olfactory environment which corresponds a more objective daily life situation.
如今，抑郁症是公共卫生领域的一个主要问题。由于涉及抑郁、嗅觉和情绪的大脑结构存在部分重叠，因此研究嗅觉功能可能是寻找抑郁特定认知标志物的一种相关方法。本研究旨在通过研究涉及中枢嗅觉通路的嗅觉参数，确定嗅觉障碍是重度抑郁发作（MDE）的状态标志物还是特征标志物。在一项初步研究中，我们前瞻性地评估了 18 名处于抑郁急性发作期的抑郁患者和抗抑郁治疗（依他普仑）6 周后的患者，将他们与 54 名年龄、性别和吸烟状况匹配的健康志愿者进行了比较。我们调查了参与者识别气味（单一气味和二元混合物）的能力，评估和区分气味强度，并确定气味的愉悦值。结果显示，一种“嗅觉快感缺失”，表现为对高情绪气味愉悦值的降低，这可能是 MDE 的状态标志物。此外，这些患者在气味强度评估过程中经历了“嗅觉负变觉”，并且无法正确识别二元等混合物中两种具有相反效价的气味，这构成了疾病的潜在特征标志物。本研究为与 MDE 相关的嗅觉障碍（状态标志物）提供了初步证据，这些障碍在抑郁症状的临床改善后仍然存在（特征标志物）。这些结果可能是由于抑郁的慢性和/或治疗手段的影响（抗抑郁治疗）所致。需要进一步确认，特别是在更符合日常生活情况的复杂嗅觉环境中获得的结果。
