Introduction

Olfactory function is known to be impaired in patients with Alzheimer’s disease (AD) as well as in subjective cognitive decline (SCD) and mild cognitive impairment (MCI), which are generally considered at-risk states for developing AD. The aim of the study at hand was to identify predictors of self-reported olfaction capability (SOC), self-reported capability of perceiving specific odors (SRP), olfaction-related quality of life (ORQ), and odor identification (OIT) in patients with SCD, naMCI, and aMCI.

Methods

The sample consisted of 33 patients with SCD, 88 with naMCI, and 43 with aMCI who consulted the Department of Neurology, Medical University of Vienna, due to memory complaints between January 2001 and May 2018. Olfactory function was assessed objectively by means of the Sniffin’ Sticks odor identification test (OIT) and subjectively by means of the ASOF-scores SOC, SRP, and ORQ at two to three points in time, with an average time interval of 39 months between the first and second examination, and 24 months between the second and third examination. Linear mixed models were used in order to identify clinical and demographic variables as predictors of mean SOC, SRP, ORQ, and OIT throughout the observation period.

Results

There was a statistically significant — albeit small — time-related decline of SOC and ORQ in the SCD group but not in other groups. Throughout the observation period, estimated ORQ was significantly higher in the SCD group than in the naMCI and estimated OIT was significantly higher in the naMCI group than in the aMCI group after adjusting for time of measurement and other covariates. Positive relationships between OIT and all three ASOF-scores, negative relationships between BDI-II and SOC and ORQ, and a positive relationship between WST-IQ and SRP were identified.

Conclusion

There is a statistically significant, albeit small, time-related decline of uncertain clinical relevance in subjective measures of olfactory capability and olfaction-related quality of life in patients with SCD.

Implications

In all subgroups, objectively measured odor-identification scores have a significant impact on subjective scores over time. The study at hand confirms previous observations regarding the negative influence of depression on subjective perception of olfactory capabilities known from cross-sectional studies.

中文翻译：

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主观认知下降和轻度认知障碍患者的长期嗅觉功能

介绍

已知阿尔茨海默病 (AD) 患者以及主观认知衰退 (SCD) 和轻度认知障碍 (MCI) 患者的嗅觉功能受损，这些通常被认为是发展为 AD 的危险状态。本研究的目的是确定自我报告的嗅觉能力（SOC）、感知特定气味的自我报告能力（SRP）、嗅觉相关的生活质量（ORQ）和气味识别（OIT）的预测因子。患有 SCD、naMCI 和 aMCI 的患者。

方法

样本包括 33 名 SCD 患者、88 名 naMCI 患者和 43 名 aMCI 患者，他们在 2001 年 1 月至 2018 年 5 月期间因记忆问题就诊于维也纳医科大学神经病学系。嗅觉功能通过 Sniffin 客观评估' 棒气味识别测试 (OIT) 和主观地通过 ASOF 评分 SOC、SRP 和 ORQ 在两到三个时间点进行，第一次和第二次检查之间的平均时间间隔为 39 个月，两次检查之间的平均时间间隔为 24 个月第二次和第三次考试。使用线性混合模型来确定临床和人口统计学变量作为整个观察期间平均 SOC、SRP、ORQ 和 OIT 的预测因子。

结果

SCD 组的 SOC 和 ORQ 与时间相关，但在其他组中没有统计显着性（尽管很小）下降。在整个观察期间，在调整测量时间和其他协变量后，SCD 组的估计 ORQ 显着高于 naMCI，并且 naMCI 组的估计 OIT 显着高于 aMCI 组。确定了 OIT 与所有三个 ASOF 分数之间的正向关系、BDI-II 与 SOC 和 ORQ 之间的负向关系以及 WST-IQ 和 SRP 之间的正向关系。

结论

在 SCD 患者的嗅觉能力和嗅觉相关生活质量的主观测量中，尽管临床相关性不确定，但与时间相关的下降具有统计学意义，但与时间相关。

影响

在所有亚组中，客观测量的气味识别分数随着时间的推移对主观分数有显着影响。手头的研究证实了先前的观察结果，即抑郁症对横断面研究已知的嗅觉能力的主观感知的负面影响。