Characteristics of the included studies for the meta-analysis.

Abbreviations: AD, Alzheimer’s disease; ApoE, Apolipoprotein E; NR, not reported; NINCDS–ADRDA, the National Institute of Neurological Disorders and Stroke–Alzheimer Diseases and Related Disorders Association Working Group criteria; DMS-IV, Diagnostic and statistical manual of mental disorders 4th Edition; BMI: body mass index; NOS, Newcastle-Ottawa Scale.Data are presented as Mean ± SD;a: Mean ± SD values were obtained from corresponding authors.b: µmol/L values were converted using molecular weight values of 34145 g/mol for ApoE.