Neuroanatomic connections link the olfactory and limbic systems potentially explaining an association between olfactory dysfunction and depression. Some previous studies have demonstrated that olfactory dysfunction is associated with increased depressive symptoms. However, these studies were cross-sectional and unable to establish which develops first. We used longitudinal data to determine if impaired odor identification increased subsequent depressive symptoms or vice versa. We assessed olfaction and depression in the National Social Life, Health, and Aging Project, a nationally representative, 15-year longitudinal study of older US adults. Olfaction was measured using a validated odor identification test (Sniffin’ Sticks). Depressive symptoms were measured using a modified version of the validated Center for Epidemiological Studies Depression Scale. Multivariable logistic regression models examined the temporal relationships between developing olfactory dysfunction and depression while accounting for demographics, disease comorbidities, alcohol use, smoking, and cognition. Older adults with olfactory dysfunction had concurrent frequent depressive symptoms (odds ratio [OR] = 1.20, 95% confidence interval [CI] = 1.00–1.43). Among healthy adults at baseline, those who had olfactory dysfunction were more likely to develop frequent depressive symptoms 5 or 10 years later (OR = 2.22, 95% CI = 1.13–4.37). Conversely, those with frequent depressive symptoms at baseline were not more likely to develop olfactory dysfunction 5 or 10 years later. We show for the first time that olfactory dysfunction predicts subsequent development of depression in older US adults. These data support screening for depression in older adults with chemosensory impairment and set the stage for disentangling the relationship between olfaction and depression.

中文翻译：

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嗅觉障碍可预测美国老年人抑郁的发展

神经解剖学联系将嗅觉和边缘系统联系起来，这可能解释了嗅觉功能障碍和抑郁症之间的关联。之前的一些研究表明，嗅觉功能障碍与抑郁症状的增加有关。然而，这些研究是横断面的，无法确定哪个先发展。我们使用纵向数据来确定受损的气味识别是否会增加随后的抑郁症状，反之亦然。我们在全国社会生活、健康和老龄化项目中评估了嗅觉和抑郁症，这是一项针对美国老年人的 15 年全国性纵向研究。使用经过验证的气味识别测试（Sniffin' Sticks）测量嗅觉。使用经验证的流行病学研究中心抑郁量表的修改版测量抑郁症状。多变量逻辑回归模型检查了发生嗅觉障碍和抑郁症之间的时间关系，同时考虑了人口统计学、疾病合并症、饮酒、吸烟和认知。有嗅觉功能障碍的老年人同时出现频繁的抑郁症状（比值比 [OR] = 1.20，95% 置信区间 [CI] = 1.00–1.43）。在基线时的健康成人中，嗅觉功能障碍者更有可能在 5 年或 10 年后频繁出现抑郁症状（OR = 2.22，95% CI = 1.13–4.37）。相反，那些在基线时经常出现抑郁症状的人在 5 或 10 年后不太可能出现嗅觉功能障碍。我们首次表明，嗅觉功能障碍预示着美国老年人随后会出现抑郁症。这些数据支持对患有化学感觉障碍的老年人进行抑郁筛查，并为理清嗅觉和抑郁之间的关系奠定基础。