Brian Sheng Yep Yeo, Harris Jun Jie Muhammad Danial Song, Benjamin Kye Jyn Tan, Adithya Suresh, Owen Tsung Wen Ho, Jun He Chan, Esther Yanxin Gao, Claire Jing-Wen Tan, Chong Boon Teo, Christopher Li-Hsian Chen, Laura Tay, Ecosse L Lamoureux, Thomas Hummel, Anna See, Shuhui Xu, Song Tar Toh, Tze Choong Charn, Neville Wei Yang Teo
{"title":"Olfactory Impairment and Incident Cognitive Decline: A Systematic Review and Meta-Analysis.","authors":"Brian Sheng Yep Yeo, Harris Jun Jie Muhammad Danial Song, Benjamin Kye Jyn Tan, Adithya Suresh, Owen Tsung Wen Ho, Jun He Chan, Esther Yanxin Gao, Claire Jing-Wen Tan, Chong Boon Teo, Christopher Li-Hsian Chen, Laura Tay, Ecosse L Lamoureux, Thomas Hummel, Anna See, Shuhui Xu, Song Tar Toh, Tze Choong Charn, Neville Wei Yang Teo","doi":"10.1002/alr.23635","DOIUrl":null,"url":null,"abstract":"<p><strong>Background: </strong>Olfactory impairment (OI) is associated with poor ageing outcomes. While cross-sectional studies found a high prevalence of OI among patients with neurodegenerative diseases, the temporal relationship remains unclear. This meta-analysis aims to synthesise the longitudinal association of OI with cognitive decline (CD).</p><p><strong>Methods: </strong>PubMed, Embase and Web of Science were searched through August 9, 2024 for longitudinal studies reporting on self-reported and objectively measured OI in adults, in association with CD, measured using validated methods. The outcome of interest was incident CD. Independent authors extracted data, assessed for bias and graded the strength of evidence. A mixed-effects meta-analysis with subgroup, sensitivity and bias analyses was conducted. The population-attributable fraction (PAF) of OI-associated CD was calculated.</p><p><strong>Results: </strong>This study included 48 articles and 37,783 participants. OI patients had a 2.06-fold greater risk of any CD (risk ratio [RR] = 2.06; 95% CI = 1.87‒2.26, I<sup>2</sup> = 0%), compared to individuals with normal olfaction. Patients with severe OI had a higher risk of any CD (RR = 2.60; 95% CI = 2.12‒3.20, I<sup>2</sup> = 0%) than patients with moderate OI (RR = 1.51; 95% CI = 1.23‒1.85, I<sup>2</sup> = 0%). The risk of any CD increased by 18% per 10% decrease in olfactory score (RR = 1.18; 95% CI = 1.14‒1.22, I<sup>2</sup> = 24%) and by 15% per point decrement on the Sniffin' Sticks Odor Identification Test (RR = 1.15; 95% CI = 1.11‒1.18, I<sup>2</sup> = 0%). These results remained robust to supplementary analyses. The PAF of OI-associated incident CD was 18%.</p><p><strong>Conclusion: </strong>OI may increase the risk of CD, with poorer olfaction linked to greater risks. OI should be assessed as a potential cognitive screening tool, and cognitive screening should be considered in patients with long-standing OI.</p>","PeriodicalId":13716,"journal":{"name":"International Forum of Allergy & Rhinology","volume":" ","pages":"e23635"},"PeriodicalIF":7.2000,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"International Forum of Allergy & Rhinology","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1002/alr.23635","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"OTORHINOLARYNGOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Background: Olfactory impairment (OI) is associated with poor ageing outcomes. While cross-sectional studies found a high prevalence of OI among patients with neurodegenerative diseases, the temporal relationship remains unclear. This meta-analysis aims to synthesise the longitudinal association of OI with cognitive decline (CD).
Methods: PubMed, Embase and Web of Science were searched through August 9, 2024 for longitudinal studies reporting on self-reported and objectively measured OI in adults, in association with CD, measured using validated methods. The outcome of interest was incident CD. Independent authors extracted data, assessed for bias and graded the strength of evidence. A mixed-effects meta-analysis with subgroup, sensitivity and bias analyses was conducted. The population-attributable fraction (PAF) of OI-associated CD was calculated.
Results: This study included 48 articles and 37,783 participants. OI patients had a 2.06-fold greater risk of any CD (risk ratio [RR] = 2.06; 95% CI = 1.87‒2.26, I2 = 0%), compared to individuals with normal olfaction. Patients with severe OI had a higher risk of any CD (RR = 2.60; 95% CI = 2.12‒3.20, I2 = 0%) than patients with moderate OI (RR = 1.51; 95% CI = 1.23‒1.85, I2 = 0%). The risk of any CD increased by 18% per 10% decrease in olfactory score (RR = 1.18; 95% CI = 1.14‒1.22, I2 = 24%) and by 15% per point decrement on the Sniffin' Sticks Odor Identification Test (RR = 1.15; 95% CI = 1.11‒1.18, I2 = 0%). These results remained robust to supplementary analyses. The PAF of OI-associated incident CD was 18%.
Conclusion: OI may increase the risk of CD, with poorer olfaction linked to greater risks. OI should be assessed as a potential cognitive screening tool, and cognitive screening should be considered in patients with long-standing OI.
期刊介绍:
International Forum of Allergy & Rhinologyis a peer-reviewed scientific journal, and the Official Journal of the American Rhinologic Society and the American Academy of Otolaryngic Allergy.
International Forum of Allergy Rhinology provides a forum for clinical researchers, basic scientists, clinicians, and others to publish original research and explore controversies in the medical and surgical treatment of patients with otolaryngic allergy, rhinologic, and skull base conditions. The application of current research to the management of otolaryngic allergy, rhinologic, and skull base diseases and the need for further investigation will be highlighted.