scholarly journals Olfactory dysfunction in Alzheimer’s disease Systematic review and meta-analysis

2018 ◽  
Vol 12 (2) ◽  
pp. 123-132 ◽  
Author(s):  
Maren de Moraes e Silva ◽  
Pilar Bueno Siqueira Mercer ◽  
Maria Carolina Zavagna Witt ◽  
Renata Ramina Pessoa

Abstract Alzheimer’s disease (AD), a neurodegenerative condition, is one of the most prevalent kinds of dementia, whose frequency doubles for every 5 years of age in elderly. Objective: To determine the correlation between AD and olfactory alterations, identifying the most affected domains and exploring the utility of olfactory tests for complementing early diagnosis. Methods: Databases were searched using the terms “olfactory OR smell OR olfaction AND alzheimer” for articles related to the proposed theme. The selected studies were categorized and evaluated separately depending on the method of analysis of the olfactory tests: identification of odors, discrimination and recognition, and a meta-analysis was carried out. Results: Fifty-one articles were selected for analysis. The effect size for most studies was large, as were the summary values for each category of individualized olfactory analysis. Conclusion: Among the olfactory domains, except memory, identification appears to be the most altered in AD. The possibility of including tests that specifically evaluate the identification of odors as an item in early diagnostic evaluation should be explored. PROSPERO registration: CRD42018089076.

2018 ◽  
Vol 31 (11) ◽  
pp. 1627-1633 ◽  
Author(s):  
Shinji Matsunaga ◽  
Hiroshige Fujishiro ◽  
Hajime Takechi

ABSTRACTObjective:The efficacy and tolerability of idalopirdine, a selective 5-hydroxytryptamine6 receptor antagonist, in patients with Alzheimer’s disease (AD) is uncertain. A systematic review and meta-analysis of randomized controlled trials (RCTs) testing idalopirdine for patients with AD was performed.Methods:We included RCTs of idalopirdine for patients with AD and used Alzheimer’s Disease Assessment Scale-cognitive subscale (ADAS-cog) scores as a primary measure.Results:Four RCTs with 2,803 patients with AD were included. There was no significant difference in ADAS-cog between the idalopirdine and placebo groups [mean difference (MD) = −0.41,P= 0.32,I2= 62%]. However, significant heterogeneity remained. Sensitivity analysis revealed that idalopirdine was more effective than placebo for ADAS-cog in the high dose and moderate AD subgroups (high dose subgroup: MD = −2.15,P= 0.005, moderate AD subgroup: MD = −2.15,P= 0.005). Moreover, meta-regression analysis showed that idalopirdine effect size for ADAS-cog was associated with mean dose (coefficient, −0.0289), ADAS-cog at baseline (coefficient, −0.9519), and proportion of male participants (coefficient, 0.2214). For safety outcomes, idalopirdine was associated with a higher incidence of at least one adverse event and increased γ-glutamyltransferase, alanine aminotransferase, aspartate aminotransferase, and vomiting than placebo. There were no significant differences in other secondary outcomes between both treatments.Conclusions:Idalopirdine is not effective for AD patients and is associated with a risk of elevated liver enzymes and vomiting. Although idalopirdine might be more effective at high doses and in moderate AD subgroups, the effect size is small and may be limited.


2021 ◽  
pp. 1-12
Author(s):  
Mingyue Qu ◽  
Hanxu Shi ◽  
Kai Wang ◽  
Xinggang Wang ◽  
Nan Yu ◽  
...  

Background: Multiple lines of evidence indicate protective effects of carotenoids in Alzheimer’s disease (AD). However, previous epidemiological studies reported inconsistent results regarding the associations between carotenoids levels and the risk of AD. Objective: Our study aims to evaluate the associations of six major members of carotenoids with the occurrence of AD by conducting a systematic review and meta-analysis. Methods: Following PRISMA guidelines, a comprehensive literature search of PubMed, Web of Science, Ebsco, and PsycINFO databases was conducted, and the quality of each included studies was evaluated by a validated scoring systems. Standardized mean differences (SMD) with 95%confidence intervals (CI) were determined by using a random effects model. Heterogeneity was evaluated by I2 statistics. Publication bias was detected using funnel plots and Egger’s test. Results: Sixteen studies, with 10,633 participants were included. Pooled analysis showed significantly lower plasma/serum levels of lutein (SMD = –0.86, 95%CI: –1.67 to –0.05, p = 0.04) and zeaxanthin (SMD = –0.59; 95%CI: –1.12 to –0.06, p = 0.03) in patients with AD versus cognitively intact controls, while α-carotene (SMD = 0.21, 95%CI: –0.68 to 0.26, p = 0.39), β-carotene (SMD = 0.04, 95%CI: –0.57 to 0.65, p = 0.9), lycopene (SMD = –0.12, 95%CI: –0.96 to 0.72, p = 0.78), and β-cryptoxanthin (SMD = –0.09, 95%CI: –0.83 to 0.65, p = 0.81) did not achieve significant differences. Conclusion: Of six major members of carotenoids, only lutein and zeaxanthin concentrations in plasma/serum were inversely related to the risk of AD. More high-quality longitudinal studies are needed to verify these findings.


2021 ◽  
pp. 101421
Author(s):  
Hema Sree G N S ◽  
V. Lakshmi Prasanna Marise ◽  
Kshreeraja S. Satish ◽  
Abhijna Vithal Yergolkar ◽  
Mamatha Krishnamurthy ◽  
...  

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