title: Preoperative cerebrospinal fluid β-Amyloid/Tau ratio and postoperative delirium.
abstract: OBJECTIVE
  The neuropathogenesis of postoperative delirium remains unknown. Low cerebrospinal fluid (CSF) βamyloid protein (Aβ) and high CSF Tau levels are associated with Alzheimer's disease. We therefore assessed whether lower preoperative CSF Aβ/Tau ratio was associated with higher incidence and greater severity of postoperative delirium.
  
  
  METHODS
  One hundred and fifty three participants (71±5 years, 53% males) who had total hip/knee replacement under spinal anesthesia were enrolled. CSF was obtained during initiation of spinal anesthesia. The incidence and severity of postoperative delirium were determined by Confusion Assessment Method (CAM) and Memorial Delirium Assessment Scale (MDAS) on postoperative day 1 and 2. Aβ40, Aβ42, and Tau levels in the CSF were measured by enzyme-linked immunosorbent assay. The relationships among these variables were determined, adjusting for age and gender.
  
  
  RESULTS
  Participants in the lowest quartile of preoperative CSF Aβ40/Tau and Aβ42/Tau ratio had higher incidence (32% versus 17%, P=0. 0482) and greater symptom severity of postoperative delirium (Aβ40/Tau ratio: 4 versus 3, P=0. 034; Aβ42/Tau ratio: 4 versus 3, P=0. 062, the median of the highest Memorial Delirium Assessment Scale score) as compared to the combination of the rest of the quartiles. The preoperative CSF Aβ40/Tau or Aβ42/Tau ratio was inversely associated with Memorial Delirium Assessment Scale score (Aβ40/Tau ratio: -0.12±0.05, P=0.014, adj. -0.12±0.05, P=0.018; Aβ42/Tau ratio: -0.65±0.26, P=0.013, adj. -0.62±0.27, P=0.022).
  
  
  CONCLUSIONS
  Lower CSF Aβ/Tau ratio could be associated with postoperative delirium, pending confirmation of our preliminary results in further studies. These findings suggest potential roles of Aβ and/or Tau in postoperative delirium neuropathogenesis.
authors.affiliation: Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129-2060.
authors.forename: Zhongcong
authors.initials: Z
authors.lastname: Xie
authors.affiliation: Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129-2060.
authors.forename: Celeste A
authors.initials: CA
authors.lastname: Swain
authors.affiliation: Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129-2060.
authors.forename: Sarah A P
authors.initials: SA
authors.lastname: Ward
authors.affiliation: MGH Biostatistics Center, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114.
authors.forename: Hui
authors.initials: H
authors.lastname: Zheng
authors.affiliation: Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129-2060.
authors.forename: Yuanlin
authors.initials: Y
authors.lastname: Dong
authors.affiliation: Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114.
authors.forename: Neelakantan
authors.initials: N
authors.lastname: Sunder
authors.affiliation: Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114.
authors.forename: Dennis W
authors.initials: DW
authors.lastname: Burke
authors.affiliation: Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129-2060.
authors.forename: Diana
authors.initials: D
authors.lastname: Escobar
authors.affiliation: Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129-2060.
authors.forename: Yiying
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Divisions of General Medicine and Primary Care and Gerontology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215.
authors.forename: Edward R
authors.initials: ER
authors.lastname: Marcantonio
keywords: Aβ/Tau ratio; Cerebrospinal fluid; delirium; surgery