Postoperative cognitive dysfunction (POCD) is an increasing problem in elderly patients. The cause is unknown and although the type of anesthetic is probably not implicated, there may be a contribution from drugs given perioperatively. Cerebral cholinergic transmission is of great importance in cognitive function. Drugs with anticholinergic properties are given during the perioperative phase.
Dr. Luzius A. Steiner, Department of Anesthesia, Surgical Intensive Care, Prehospital Emergency Medicine and Pain Therapy, University Hospital Basel, Basel, Switzerland, and colleagues from Switzerland and Canada measured total serum anticholinergic activity (SAA) and cognitive function before and 7 days after major surgery in 79 elderly patients. The authors’ results are published in this month’s edition of Anesthesia and Analgesia in the article “Serum Anticholinergic Activity and Postoperative Cognitive Dysfunction in Elderly Patients.”
The results from 70 patients were available for analysis. The authors found that patients who developed POCD were older and less educated than patients without POCD. The investigators found no association between POCD and SAA. They concluded that perioperative anticholinergic medication is unlikely to make a substantial contribution to POCD. These findings confirm the results of previous studies.
The authors highlighted the difficulties in measuring POCD and the wide variability in reported incidence. The radioreceptor assay used to measure SAA is based on affinity for rat striatum muscarinic receptors, which may not represent binding to receptors in human brains and excludes nicotinic activity. Additionally, the assay does not measure possible direct effects of anesthetic drugs on central cholinergic transmission. Measurement of stress hormones, particularly cortisol, and inflammatory markers would have been useful in trying to elucidate possible mechanisms for the development of POCD.
This paper provides great insight into the difficulties of research on this topic. Just how difficult is it, you might ask? So far there isn’t even a consensus on the definition of POCD!