title: Testosterone, Estradiol, and Sex Hormone-Binding Globulin in Alzheimer's Disease: A Meta-Analysis.
abstract: BACKGROUND
  Previous studies suggested that plasma sex hormones may be implicated in the pathogenesis of Alzheimer's disease (AD). However, the relationship between sex hormones and AD remains unclear.
  
  
  OBJECTIVE
  To systematically review and quantitatively analyze studies observing plasma total testosterone (TT), estradiol (E2), and sex hormone-binding globulin (SHBG) levels among AD patients.
  
  
  METHODS
  Medline, EMBASE, the Cochrane Library, and PsycINFO were searched for studies published prior to March 28(th), 2014. Published studies that reported plasma levels of TT, E2, and SHBG in AD and matched controls were included in the present meta-analysis.
  
  
  RESULTS
  Meta-analysis was performed using the random effects model, expressing continuous outcomes as the mean difference (MD) between AD and control populations. The 95% confidence intervals (CI) were also calculated. No differences were found in plasma levels of TT and E2 between AD and matched controls (TT MD -0.17 nmol/l, 95% CI -0.54, 0.20; E2 MD -1.16 pmol/l, 95% CI -9.85, 6.83). Plasma levels of SHBG were significantly increased in AD patients compared to healthy controls (SHBG MD 12.94 nmol/l, 95% CI 2.68, 23.20).
  
  
  CONCLUSIONS
  Patients with AD had higher plasma levels of SHBG. The up-regulated levels of plasma SHBG show preliminary supportive evidence that SHBG and the bioavailability of functional sex hormones in plasma may be linked to the pathogenesis of AD.
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.forename: Lei-Lei
authors.initials: LL
authors.lastname: Xia
authors.forename: Ning
authors.initials: N
authors.lastname: Song
authors.affiliation: Department of Neurology & Institute of Neurology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China. chen_sd@medmail.com.cn.
authors.forename: Sheng-Di
authors.initials: SD
authors.lastname: Chen
authors.affiliation: Department of Neurology & Institute of Neurology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China. wgneuron@hotmail.com.
authors.forename: Gang
authors.initials: G
authors.lastname: Wang
mesh_terms: D000544:Alzheimer Disease / Q000097:blood* / Q000175:diagnosis*; D015415:Biomarkers / Q000097:blood; D004958:Estradiol / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism*; D013739:Testosterone / Q000097:blood*
chemical_list: D015415:Biomarkers; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D004958:Estradiol