Chenping Zhang1, Xiaochun Wang2. 1. School of Kinesiology, Shanghai University of Sport, 399 Chang Hai Road, Shanghai, 200438, P.R. China. 2. School of Kinesiology, Shanghai University of Sport, 399 Chang Hai Road, Shanghai, 200438, P.R. China. Electronic address: wangxiaochun@sus.edu.cn.
Abstract
BACKGROUND: Aging is an important contributor to olfactory system deterioration in humans, leading to increased health and safety risks as well as affecting the quality of life. However, it is currently unknown when age-related olfactory deterioration begins in humans and thus when to initiate interventions to prevent or slow it. OBJECTIVE: To determine the decade in which olfactory function begins to deteriorate in healthy humans by determining when odor identification is first impaired. DATA SOURCE AND STUDY SELECTION: Studies cited in the PubMed database were searched from its inception to March 2017 using the terms "olfac*" or "smell" and "ag*". The effect size of each comparison was calculated. RESULTS: In this meta-analysis, the effect sizes as determined using Cohen's d for the comparisons between 30 and 39.9- and 40-49.9-year-olds was 0.06 (95% CI: -0.17 to 0.29), between 40-49.9-year-olds was 0.62 (95% CI: 0.20-1.04), considered a medium effect size, and between 35-55-year-olds and those >55years old was 1.12 (95% CI: 1.06-1.45), considered a very large effect. CONCLUSION: Olfactory function deterioration, as determined by an impaired ability to identify odors, starts in the fifth decade of life in healthy humans.
BACKGROUND: Aging is an important contributor to olfactory system deterioration in humans, leading to increased health and safety risks as well as affecting the quality of life. However, it is currently unknown when age-related olfactory deterioration begins in humans and thus when to initiate interventions to prevent or slow it. OBJECTIVE: To determine the decade in which olfactory function begins to deteriorate in healthy humans by determining when odor identification is first impaired. DATA SOURCE AND STUDY SELECTION: Studies cited in the PubMed database were searched from its inception to March 2017 using the terms "olfac*" or "smell" and "ag*". The effect size of each comparison was calculated. RESULTS: In this meta-analysis, the effect sizes as determined using Cohen's d for the comparisons between 30 and 39.9- and 40-49.9-year-olds was 0.06 (95% CI: -0.17 to 0.29), between 40-49.9-year-olds was 0.62 (95% CI: 0.20-1.04), considered a medium effect size, and between 35-55-year-olds and those >55years old was 1.12 (95% CI: 1.06-1.45), considered a very large effect. CONCLUSION: Olfactory function deterioration, as determined by an impaired ability to identify odors, starts in the fifth decade of life in healthy humans.
Authors: Mira Fitzek; Parthkumar K Patel; Peter D Solomon; Brian Lin; Thomas Hummel; James E Schwob; Eric H Holbrook Journal: J Comp Neurol Date: 2022-04-09 Impact factor: 3.028
Authors: K S Fluitman; H J Nadar; D S Roos; H W Berendse; B J F Keijser; M Nieuwdorp; R G Ijzerman; M Visser Journal: J Nutr Health Aging Date: 2019 Impact factor: 4.075