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Olfactory perception and blindness: a systematic review and meta-analysis.

ABSTRACT: Anecdotal reports suggest that blind people might develop supra-normal olfactory abilities. However, scientific evidence shows a mixed pattern of findings. Inconsistent observations are reported for both sensory-driven olfactory tasks (e.g., odor threshold) and higher-order olfactory functions (e.g., odor identification). To quantify the evidence systematically, we conducted a review and meta-analysis. Studies were included if they examined olfactory function (i.e., odor threshold, odor discrimination, free odor identification, or cued odor identification) in blind compared with a sighted control group. Articles were identified through computerized literature search. A total of 18 studies focused on olfactory threshold (n?=?1227: 590 blind and 637 sighted individuals), 14 studies targeted discrimination (n?=?940: 455 blind and 485 sighted), 14 studies measured cued identification (n?=?968: 468 blind and 500 sighted), and 7 studies (n?=?443: 224 blind and 219 sighted individuals) assessed free identification. Overall, there were no differences in effect sizes between the blind and sighted individuals after correcting the results for publication bias. We additionally conducted an exploratory analysis targeting the role played by three moderators of interests: participants' age, the proportion of women versus men in each of the studies included into meta-analysis and onset of blindness (early blind vs. late-blind). However, none of the moderators affected the observed results. To conclude, blindness seems not to affect cued/free odor identification, odor discrimination or odor thresholds.

SUBMITTER: Sorokowska A

PROVIDER: S-EPMC6794238 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature

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Olfactory perception and blindness: a systematic review and meta-analysis.

Sorokowska Agnieszka A Sorokowski Piotr P Karwowski Maciej M Larsson Maria M Hummel Thomas T

Psychological research 20180612 8

Anecdotal reports suggest that blind people might develop supra-normal olfactory abilities. However, scientific evidence shows a mixed pattern of findings. Inconsistent observations are reported for both sensory-driven olfactory tasks (e.g., odor threshold) and higher-order olfactory functions (e.g., odor identification). To quantify the evidence systematically, we conducted a review and meta-analysis. Studies were included if they examined olfactory function (i.e., odor threshold, odor discrimi ...[more]

PMID: 29948185

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Project description:Cataract is the second leading cause of visual impairment and the first of blindness globally. However, for the most populous country, China, much remains to be understood about the scale of cataract and cataract blindness. We aimed to investigate the prevalence of cataract and cataract blindness in China at both the national and subnational levels, with projections till 2050.In this systematic review and meta-analysis, China National Knowledge Infrastructure (CNKI), Wanfang, Chinese Biomedicine Literature Database (CBM-SinoMed), PubMed, Embase, and Medline were searched using a comprehensive search strategy to identify all relevant articles on the prevalence of cataract or cataract blindness in Chinese population published from January 1990 onwards. We fitted a multilevel mixed-effects meta-regression model to estimate the prevalence of cataract, and a random-effects meta-analysis model to pool the overall prevalence of cataract blindness. The United Nations Population Division (UNPD) data were used to estimate and project the number of people with cataract and cataract blindness from 1990 to 2050. According to different demographic and geographic features in the six geographic regions in China, the national numbers of people with cataract in the years 2000 and 2010 were distributed to each region.In males, the prevalence of any cataract (including post-surgical cases) ranged from 6.71% (95% CI?=?5.06-8.83) in people aged 45-49 years to 73.01% (95% CI?=?65.78-79.2) in elderly aged 85-89 years. In females, the prevalence of any cataract increased from 8.39% (95% CI?=?6.36-10.98) in individuals aged 45-49 years to 77.51% (95% CI?=?71.00-82.90) in those aged 85-89 years. For age-related cataract (ARC, including post-surgical cases), in males, the prevalence rates ranged from 3.23% (95% CI?=?1.51-6.80) in adults aged 45-49 years to 65.78% (95% CI?=?46.72-80.82) in those aged 85-89 years. The prevalence of ARC in females was 4.72% (95% CI?=?2.22-9.76) in the 45-49 years age group and 74.03% (95% CI?=?56.53-86.21) in the 85-89 years age group. The pooled prevalence rate of cataract blindness (including post-surgical cases) by best corrected visual acuity (BCVA)<0.05 among middle-aged and older Chinese was 2.30% (95% CI?=?1.72-3.07), and those of cataract blindness by BCVA<0.10 and cataract blindness by presenting visual acuity (PVA)<0.10 were 2.56% (95% CI?=?1.94-3.38) and 4.51% (95% CI?=?3.53-5.75) respectively. In people aged 45-89 years, the number of any cataract cases was 50.75 million (95% CI?=?42.17-60.37) in 1990 and 111.74 million (95% CI?=?92.94-132.84) in 2015, and that of ARC rose from 35.77 million (95% CI?=?19.81-59.55) in 1990 to 79.04 million (95% CI?=?44.14-130.85) in 2015. By 2050, it is projected that the number of people (45-89 years of age) affected by any cataract will be 240.83 million (95% CI?=?206.07-277.35), and that of those with ARC will be 187.26 million (95% CI?=?113.17-281.23). During 2000 and 2010, South Central China consistently owed the most cases of any cataract, whereas Northwest China the least.The prevalence of cataract and cataract blindness in China was unmasked. In the coming decades, cataract and cataract blindness will continue to be a leading public-health issue in China due to the ageing population. Future work should be prioritized to the promotion of high-quality epidemiological studies on cataract.

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Dataset Information

Olfactory perception and blindness: a systematic review and meta-analysis.

Publications

Olfactory perception and blindness: a systematic review and meta-analysis.

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