Abstract
Alzheimer’s disease International (ADI) estimates that there are currently 30 million people with dementia in the world. The main objective was to perform meta-analysis of studies of CSF tau and Amyloid β42 (Aβ42) levels in Alzheimer’s disease (AD) patients and controls. In the present study MEDLINE was reviewed from 1995 to 2009, supplemented by citation analysis from retrieved articles to select case control studies. Descriptive statistics showed that median effect size (raw mean difference) of CSF tau and Aβ42 levels were 301 pg/ml (Range: 22 to 614 pg/ml) and –352 pg/ml (Range: –969 to 203 pg/ml) respectively. The pooled effect size CSF tau and Aβ42 was 289.14 pg/ml (95% CI 253.278 to 325.013 pg/ml) and –329.02 pg/ml (95% CI –387.740 to –270.445 pg/ml) respectively. Heterogeneity in effect size of selected studies was present for both parameters (CSF tau: Q statistics = 1816.596, DF = 40, P = 0.000 and CSF Aβ42: Q-statistics = 1259.358, DF = 24, p 42 levels in AD and controls may be considered as potential biomarker along with the clinical phenotype to perform them during high quality diagnostic testing in dementia.
Highlights
Alzheimer’s disease International (ADI) estimates that there are currently 30 million people with dementia in the world and will increase to be over 100 million by 2050 [1]
Out of 60 publications retrieved from the MEDLINE search, 19 studies were excluded as in 10 studies Standard Deviation (SD) was not expressed in their tau mean value, in 5 studies controls were not provided in the data whereas in 2 studies each immunoblotting technique was used to measure tau and tau was expressed in pmol/L. 41 case-control published studies of Alzheimer’s disease that were meeting the inclusion criteria for meta-analysis, were identified (Table 1 & Figure 1) [9,10,12,13,16,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55]
The overall effect size (CSF tau level difference between AD and control subjects) of the meta-analysis of published studies was 289.14 pg/ml (Table 2 & Figure 1)
Summary
Alzheimer’s disease International (ADI) estimates that there are currently 30 million people with dementia in the world and will increase to be over 100 million by 2050 [1]. A broad consensus exists to revise these criteria owing to the advances occurring in our understanding of AD, development of biomarkers to detect the pathophysiological process of AD and changes in conceptualization regarding the clinical spectrum of the disease in the intervening 27 years [3]. The National Institute on aging (NIA) and the Alzheimer’s Association sponsored a series of advisory round table meetings in 2009 for revising the diagnostic and research criteria for AD in three stages-preclinical phase, predementia phase and symptomatic phase of AD. In the symptomatic predementia MCI phase, biomarkers are used to establish the underlying etiology responsible for the clinical deficit and biomarker severity indicates likelihood of imminent progression to AD dementia. Biomarkers are used to increase or decrease the level of certainty that AD pathophysiology
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