Meta Analysis On The Association Between Plasma Homocysteine And Mild Cognitive Impairment Of The Aged

Background Mild cognitive impairment (MCI) meant the elderlyappeared mild memory or cognitive dysfunction, but not enough todiagnosis of clinical dementia. It was the transitional state between normalcognitive aging and dementia. MCI patients haven higher risk to changedementia. It could prevent or postpone to change dementia through earlyintervention of MCI. Homocysteine (Hcy) was a sulfur amino acids whichcan`t synthesize in human body. It was the important middle metabolites ofmethionine which was a essential amino acids in human body. It wasidentified as an independent risk factor for cardiovascular disease, mighthave a certain impact on the cognitive disorder diseases. Therefore, a lot ofresearchs on the association between Hcy and MCI were analyzed, foundthe relation between the Hcy and MCI, provided a basis for earlyintervention of MCI. Because of differences in research methods, area, andresearch object, the research results were not consistent, needed furtheranalysis and evaluation.Objective To evaluate the literatures which was association betweenmild cognitive impairment (MCI) of the aged and plasma homocysteine(Hcy) level through Meta analysis. To explore the related evidence betweenHcy and MCI. Provided ideas for early intervention of MCI.Methods Published literatures which was case-control study association between Hcy and MCI in2003-2014were searched throughlarge literature databases, including PubMed, BIOsis Previews, Medline,EBSCO, CBM, CNKI, etc. Retrieval words were: mild cognitiveimpairment, homocysteine, connecting with the conjunction “AND” and“OR”. Screened literatures through the strict inclusion and exclusioncriteria. Inclusion criteria:①independent case-control study;②The casegroup were older than60years old, Petersen diagnostic criteria fordiagnosis of patients with MCI;③The control group with normalcognitive function and older than60years old;④Hcy detected withfasting venous blood;⑤Could be directly extracted or calculated samplecontent, the mean and standard deviation of plasma Hcy content. Exclusioncriteria:①The case or control with other cognitive disorders;②literatureof Review, meeting minutes, animal experimental;③Duplicate documents;④Couldn`t be directly extracted or calculated sample content, the meanand standard deviation of plasma Hcy content. The quality of studies wasevaluated by Newcastle-Ottawa Scale (NOS), out of9, with higher scoresindicating better quality. Two researchers extracted relevant data fromultimately included literature. According to the analysis of theheterogeneity, Selected appropriate effect model. RevMan5.2software wasused to do Meta analysis. Calculated the standardized mean difference(SMD) and its95%confidence interval (CI) of the plasma Hcy content, andtested the overall effects. Make sensitivity analysis by changing in theeffect model and excluding study of low quality, to judge the stability ofresults. Funnel plot and fail-safe number (Nfs) were performed forevaluating the publication bias. Based on the analysis results of the heterogeneity, STATA11software was used to make subgroup analysis.Results Eleven qualified studies were identified, including737patients and866controls. There was remarkable heterogeneity among thestudies (χ2=106.87,k=10,P＜0.05,I2=91%). The random effect model ofMeta analysis showed the standardized mean difference and95%confidence interval of Hcy concentrations was0.92(0.57,1.27), indicatinghigher Hcy levels in MCI patients(P＜0.05). The analytical result ofsensitivity proved that the Meta-analysis was stability. Throughsymmetrical funnel plot and Nfs0.05(1370.949), the publication bias hadbeen well controlled. Subgroup analysis of the area showed that theheterogeneity of Chinese group decreased, but still existed (I2=86.1%).SMD of the Chinese group was1.18,95%CI was0.78~1.57. Based on thesubgroup analysis of the age, SMD of less than70years old group was1.20,95%CI was1.04~1.36; SMD of more than70years old group was0.60,95%CI was0.46~0.74. Elevated Hcy concentration had correlationwith MCI. The heterogeneity decreased，but there was still.Conclusions Higher concentration of plasma Hcy was relational withMCI. Monitoring of Hcy levels might have important significance forprevention and treatment of MCI. Prospective studies in the risk ofdeveloping MCI were needed, preferably in the form of cohort study andRCTs in large population.