Association of Biochemical Markers with Postoperative Delirium and Cognitive Dysfunction in Elderly Orthopedic Patients

Background

The growing elderly population has increased susceptibility to postoperative neurocognitive disorders, particularly delirium (POD) and cognitive dysfunction (POCD). POD occurs in 14–60% and POCD in 30–50% of older surgical patients. Emerging evidence implicates neuroinflammation, oxidative stress, and neuronal dysfunction. We hypothesize that Brain-Derived Neurotrophic Factor (BDNF) and Malondialdehyde (MDA) biomarkers may predict POD and POCD risk.

Methods

This prospective observational cohort study (IEC approval: 283/07.05.2021; CTRI/2024/12/077549) enrolled 80 patients >60 years undergoing major orthopaedic surgery. After informed consent, baseline demographics, comorbidities, and laboratory parameters were recorded. Cognitive and neuropsychiatric assessments were conducted pre and postoperatively using standardized psychological scales. Serum levels of biochemical markers, BDNF and MDA were measured using ELISA at both time points.

Results

The cohort had a mean age of 67.67 ± 6.2 years (44 males, 36 females) and mean BMI of 23.08 ± 4.2. Comorbidities were diabetes (17), hypertension (11), thyroid disorders (8), and hypercholesterolemia (11), where most cases were ASA Grade I (62) with 18 cases of PONV. Cognitive assessments revealed a significant postoperative decline in ACE-III (p = 0.01) and DRS-R-98 (p = 0.0001) scores with no significant changes in TMT-B, Stroop Test, or Porteus Maze scores. MDA levels demonstrated a near-significant reduction (885.01 ± 891.26 to 670.35 ± 570.41 nmol/mL; p = 0.07), indicating a possible decrease in oxidative stress post-surgery.

Conclusion

This study reveals a high risk of POD and POCD among elderly patients undergoing major orthopedic surgery. Significant cognitive decline by ACE-III and DRS-R-98 scores was observed postoperatively. MDA levels suggest a potential role of oxidative stress in cognitive outcomes. These findings highlight the importance of routine cognitive assessment and biochemical monitoring in the perioperative period. Further research is needed to confirm these associations and to develop preventive strategies.