Cerebrospinal Fluid β-Amyloid and Tau Are Not Associated with Risk of Delirium: A Prospective Cohort Study in Older Adults with Hip Fracture

OBJECTIVES: To examine the association between cerebrospinal fluid (CSF) β‐amyloid (Aβ1–42), tau, and hyperphosphorylated tau (Ptau) and risk of delirium in older adults with hip fracture. DESIGN: Prospective cohort study. SETTING: University‐affiliated general hospital in Alkmaar, the Netherlands. PARTICIPANTS: Seventy‐six participants aged 75 and older admitted for surgical repair of acute hip fracture. MEASUREMENTS: Presurgical baseline screening and assessment included the Informant Questionnaire on Cognitive Decline—short form (IQCODE‐N), Mini‐Mental State Examination, standardized Snellen test for visual impairment, Geriatric Depression Scale, Barthel Index (BI), and Lawton Instrumental Activity of Daily Living (IADL) scale. The number of medical comorbidities and medications at home, American Society of Anesthesiologists score, and Acute Physiology and Chronic Health Evaluation II score were determined according to chart review. Delirium was diagnosed using the Confusion Assessment Method. CSF was collected at the onset of spinal anesthesia. RESULTS: Postoperative delirium occurred in 30 (39.5%) participants. Participants with delirium were older, showed more signs of cognitive decline, were more dependent at home in activity of daily living and IADL functioning, and used more medications before admission. Preoperative CSF Aβ1‐42, tau, and Ptau levels were not significantly different in participants who did and did not develop delirium during subsequent hospitalization. In contrast, prefracture cognitive decline (IQCODE‐N) was significantly related to delirium (odds ratio=9.43, 95% confidence interval=2.45–36.31). CONCLUSION: Cognitive impairment predisposes to delirium, but in this study, postoperative delirium was not associated with baseline CSF Aβ1‐42, tau, and Ptau levels. These findings suggest that CSF markers for plaque and tangle formation are not strongly associated with delirium risk in older adults with hip fracture.