{"title":"Effects of Olfactory Training on Olfactory and Cognitive Function: A Systematic Review.","authors":"Yangzi Tan, Xiangxian Liu, Yankun Li, Xiaolu Liu, Yali Du, Danhua Zhao, Dawei Wu","doi":"10.1177/01455613251384121","DOIUrl":null,"url":null,"abstract":"<p><strong>Background: </strong>Olfactory training (OT) interventions exhibit dual therapeutic potential, enhancing both chemosensory function and multiple cognitive domains through neuroplastic mechanisms.</p><p><strong>Objective: </strong>To systematically review the efficacy of OT on olfaction, cognition, and neuroimaging changes across a range of populations, from healthy adults to patients with olfactory and cognitive impairments.</p><p><strong>Methods: </strong>A systematic review was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A comprehensive search of PubMed, Embase, Web of Science, and Cochrane databases performed to identify studies that evaluate the effect of OT on olfaction and cognition in different populations, focusing on its potential to enhance cognition and mitigate the progression of cognitive decline.</p><p><strong>Results: </strong>Of the initial 412 abstracts reviewed, 24 full-text articles were included. Risk-of-bias assessment revealed 7/12 randomized controlled studies (RCTs) had high risk and 11/12 non-RCTs had serious bias. The duration of OT interventions mostly ranged from 3 to 6 months. In healthy adults (6 studies) and adults with olfactory dysfunction (13 studies), OT improved olfactory function in a population-dependent manner and exerted domain-specific cognitive benefits. Meta-analysis revealed that the pooled proportion of individuals achieving a clinically-significant olfactory improvement was 27.01% (95% confidence interval, 0.16-0.40). Improvements were observed in global cognition, verbal fluency, and working memory. In adults with cognitive impairment (5 studies), classical OT showed limited olfactory and cognitive improvements; however, intensive OT with enriched odors, longer sessions, and greater adherence demonstrated potential for enhanced cognitive and emotional outcomes in patients with dementia. Furthermore, the reviewed neuroimaging studies consistently demonstrate that OT can increase volumes in several brain regions and promote neuronal reorganization, providing a potential mechanism of OT in olfactory recovery and cognitive improvement.</p><p><strong>Conclusions: </strong>OT effectively improves olfaction, cognition, and brain health, particularly in cognitively-normal populations.</p>","PeriodicalId":93984,"journal":{"name":"Ear, nose, & throat journal","volume":" ","pages":"1455613251384121"},"PeriodicalIF":0.7000,"publicationDate":"2025-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Ear, nose, & throat journal","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1177/01455613251384121","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
Background: Olfactory training (OT) interventions exhibit dual therapeutic potential, enhancing both chemosensory function and multiple cognitive domains through neuroplastic mechanisms.
Objective: To systematically review the efficacy of OT on olfaction, cognition, and neuroimaging changes across a range of populations, from healthy adults to patients with olfactory and cognitive impairments.
Methods: A systematic review was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A comprehensive search of PubMed, Embase, Web of Science, and Cochrane databases performed to identify studies that evaluate the effect of OT on olfaction and cognition in different populations, focusing on its potential to enhance cognition and mitigate the progression of cognitive decline.
Results: Of the initial 412 abstracts reviewed, 24 full-text articles were included. Risk-of-bias assessment revealed 7/12 randomized controlled studies (RCTs) had high risk and 11/12 non-RCTs had serious bias. The duration of OT interventions mostly ranged from 3 to 6 months. In healthy adults (6 studies) and adults with olfactory dysfunction (13 studies), OT improved olfactory function in a population-dependent manner and exerted domain-specific cognitive benefits. Meta-analysis revealed that the pooled proportion of individuals achieving a clinically-significant olfactory improvement was 27.01% (95% confidence interval, 0.16-0.40). Improvements were observed in global cognition, verbal fluency, and working memory. In adults with cognitive impairment (5 studies), classical OT showed limited olfactory and cognitive improvements; however, intensive OT with enriched odors, longer sessions, and greater adherence demonstrated potential for enhanced cognitive and emotional outcomes in patients with dementia. Furthermore, the reviewed neuroimaging studies consistently demonstrate that OT can increase volumes in several brain regions and promote neuronal reorganization, providing a potential mechanism of OT in olfactory recovery and cognitive improvement.
Conclusions: OT effectively improves olfaction, cognition, and brain health, particularly in cognitively-normal populations.
背景：嗅觉训练（OT）干预具有双重治疗潜力，通过神经可塑性机制增强化学感觉功能和多个认知领域。目的：系统回顾OT对从健康成人到嗅觉和认知障碍患者的一系列人群的嗅觉、认知和神经影像学变化的影响。方法：根据系统评价和荟萃分析指南的首选报告项目进行系统评价。我们对PubMed、Embase、Web of Science和Cochrane数据库进行了全面的检索，以确定评估OT对不同人群嗅觉和认知影响的研究，重点关注其增强认知和减缓认知衰退进展的潜力。结果：在最初审查的412篇摘要中，包括24篇全文文章。风险偏倚评估显示，7/12的随机对照研究（rct）存在高风险，11/12的非随机对照研究存在严重偏倚。OT干预的持续时间大多为3至6个月。在健康成人（6项研究）和嗅觉功能障碍成人（13项研究）中，OT以人群依赖的方式改善嗅觉功能，并发挥特定领域的认知益处。荟萃分析显示，获得临床显著嗅觉改善的个体的总比例为27.01%（95%可信区间为0.16-0.40）。在整体认知、语言流畅性和工作记忆方面观察到改善。在有认知障碍的成人中（5项研究），经典OT显示出有限的嗅觉和认知改善；然而，气味丰富的强化OT、更长的治疗时间和更强的依从性表明，痴呆患者的认知和情绪结果有可能得到改善。此外，所回顾的神经影像学研究一致表明，OT可以增加大脑多个区域的体积并促进神经元重组，这为OT在嗅觉恢复和认知改善中的潜在机制提供了可能。结论：OT能有效改善嗅觉、认知和大脑健康，尤其是在认知正常人群中。
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