Cerebrospinal fluid aβ to tau ratio and postoperative cognitive change

Determination of biomarker and neuropathogenesis of postoperative cognitive change (POCC) or postoperative cognitive dysfunction.

POCC is one of the most common postoperative complications in elderly patients. Whether preoperative cerebrospinal fluid (CSF) β-amyloid protein (Aβ) to tau ratio, an Alzheimer disease biomarker, is a biomarker for risk of POCC remains unknown. We therefore set out to assess the association between preoperative CSF Aβ42 or Aβ40 to tau ratio and POCC.

Patients who had total hip/knee replacement were enrolled. The CSF was obtained during the administration of spinal anesthesia. Cognitive tests were performed with these participants at 1 week before and at 1 week and 3 to 6 months after the surgery. Z scores of the changes from preoperative to postoperative on several key domains of the cognitive battery were determined. We then examined the association between preoperative CSF Aβ42/tau or Aβ40/tau ratio and the outcome measures described earlier, adjusting for age and sex.

Among the 136 participants (mean age = 71 ± 5 years; 55% men), preoperative CSF Aβ42/tau ratio was associated with postoperative Hopkins Verbal Learning Test Retention [Z score = 8.351; age, sex-adjusted (adj.) P = 0.003], and the Benton Judgment of Line Orientation (Z score = 1.242; adj. P = 0.007). Aβ40/tau ratio was associated with Brief Visuospatial Memory Test Total Recall (Z score = 1.045; adj. P = 0.044).

Preoperative CSF Aβ/tau ratio is associated with postoperative changes in specific cognitive domains. The presence of the Alzheimer's disease biomarker, specifically the Aβ/tau ratio, may identify patients at higher risk for cognitive changes after surgery.