A new study published in Communications Biology has identified a potential biomarker for postoperative cognitive decline in elderly patients. Researchers have found that low levels of S-methyl-5-thioadenosine (MTA) in the blood are associated with delayed neurocognitive recovery (dNCR) following surgery. The study, which combined clinical investigations with animal models, suggests that maintaining adequate MTA levels could be crucial for cognitive health after surgical procedures.
Clinical Findings: MTA Levels and Cognitive Outcomes
The clinical investigation involved 67 participants aged 65 years or older undergoing neck and maxillofacial tumor resection under general anesthesia. Researchers assessed cognitive function using the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scales before and after surgery. A decrease of one standard deviation (SD) in both scales after surgery was considered dNCR. The study revealed that 25 of the 67 participants exhibited dNCR.
Analysis of blood samples showed a significant decrease in MTA levels 24 hours after surgery in patients who experienced dNCR. This suggests a correlation between reduced MTA levels and postoperative cognitive impairment. According to the study, "low blood S-methyl-5-thioadenosine is associated with postoperative delayed neurocognitive recovery."
Animal Model Experiments: Mechanistic Insights
To further investigate the role of MTA in postoperative cognitive dysfunction, researchers conducted experiments using aged mice. The mice were subjected to anesthesia and a surgical procedure involving exposure of the carotid artery. Consistent with the clinical findings, the animal models also showed a decrease in MTA levels in cortical tissues after anesthesia and surgery.
Interestingly, when the mice were administered MTA or methionine (a precursor to MTA) prior to anesthesia and surgery, they exhibited improved cognitive performance in spatial learning and memory tests. This suggests that increasing MTA levels can protect against postoperative cognitive decline. The study authors noted, "MTA administration before anesthesia/surgery reversed these effects, indicating that MTA plays a protective role."
Implications for Postoperative Care
These findings have significant implications for postoperative care, particularly for elderly patients who are at a higher risk of cognitive complications. Monitoring MTA levels in patients undergoing surgery could help identify those who are more likely to experience postoperative cognitive decline. Furthermore, interventions aimed at maintaining or increasing MTA levels, such as dietary supplementation with methionine, could potentially mitigate these cognitive issues.
The researchers emphasize the need for further studies to validate these findings and explore the potential therapeutic benefits of MTA supplementation in humans. However, this study provides valuable insights into the mechanisms underlying postoperative cognitive dysfunction and highlights a promising avenue for future research and clinical interventions.
