Do fluctuations in endogenous melatonin levels predict the occurrence of postoperative cognitive dysfunction (POCD)?

Area of Science:

• Neuroscience
• Gerontology
• Pharmacology

Background:

• Delirium, a neuropsychiatric disorder, negatively impacts central nervous system (CNS) function.
• Postoperative delirium (POD) in elderly patients is characterized by abnormal melatonin secretion patterns.
• POD is closely associated with early postoperative cognitive dysfunction (POCD).

Purpose of the Study:

• To investigate whether significant perioperative fluctuations in melatonin secretion indicate postoperative cognitive dysfunction (POCD).

Main Methods:

• 97 elderly patients (65-80 years) undergoing major surgery were recruited.
• Neuropsychological evaluations were conducted preoperatively and one week postoperatively.
• Urinary 6-sulfatoxymelatonin (6-SMT)/creatinine ratios were measured perioperatively to assess melatonin secretion.

Main Results:

• 31.6% of patients developed POCD one week after surgery.
• Significant melatonin secretion fluctuations (≥ twofold change from baseline) were observed in 39% of patients.
• The incidence of POCD was significantly higher in patients with 6-SMT fluctuations (p < 0.01).

Conclusions:

• Postoperative cognitive dysfunction (POCD) affects a substantial proportion of elderly patients within a week of major noncardiac surgery.
• Fluctuations in endogenous melatonin levels are linked to the development of POCD.
• Perioperative urinary 6-SMT measurement could aid in diagnosing POCD.