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Do low‐serum vitamin E levels increase the risk of Alzheimer disease in older people? Evidence from a meta‐analysis of case‐control studies
Author(s) -
Dong Yonghai,
Chen Xiaodan,
Liu Yun,
Shu Yan,
Chen Ting,
Xu Lei,
Li Meng,
Guan Xihong
Publication year - 2018
Publication title -
international journal of geriatric psychiatry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 129
eISSN - 1099-1166
pISSN - 0885-6230
DOI - 10.1002/gps.4780
Subject(s) - meta analysis , funnel plot , publication bias , confidence interval , medicine , dementia , vitamin e , cohort study , disease , prospective cohort study , gerontology , biology , biochemistry , antioxidant
Objective Whether low‐serum vitamin E increases the risk of Alzheimer disease (AD) in older people remains inconclusive. This meta‐analysis aims to synthesize evidence‐based case‐control studies to evaluate the association between serum vitamin E and the risk of AD. Methods Potentially relevant studies were selected through PubMed, Embase, Wanfang, Chongqing VIP, and China National Knowledge Infrastructure databases by using the core terms Vitamin E/alpha‐tocopherol and Alzheime's disease/senile dementia/AD in the titles, abstracts, and keywords of the articles. The association between serum vitamin E levels and AD was estimated by using the weighted mean difference (WMD) and 95% confidence interval by adopting a random effects model. Heterogeneity was assessed by using Cochran Q test and I 2 statistic. Forest plot was used to present the results graphically from meta‐analysis. Publication bias was evaluated by using funnel plots and Egger test. Results We identified 17 studies that met the eligibility criteria. The studies included 2057 subjects with 904 AD patients and 1153 controls. The results indicated that AD patients had a lower concentration of serum vitamin E compared with healthy controls among older people (WMD = −6.811 μmol/L, 95% confidence interval −8.998 to −4.625; Z = −6.105, P < .001). Publication bias was not detected and sensitivity analysis performed by omitting each study, and calculating the pooled WMD again for the remaining studies indicated the results stable. Conclusions Alzheimer disease is associated with a low concentration of serum vitamin E in older people. However, necessary prospective cohort studies should be conducted to determine the risk of serum vitamin E for AD in the future.