The group consensus, however, was that anesthesia type does not seem to influence the incidence of cognitive dysfunction, but a larger prospective randomized controlled trial focusing on older patients is warranted to definitively answer this crucial question. Dr. Trzepacz focused on the cholinergic mechanisms of postoperative delirium. She reviewed the brain areas involved in delirium and highlighted a key role of acetylcholine in the REM sleep, arousal, mood and memory changes seen in delirium. 3 Anticholinergic drugs are known to cause delirium. Dopamine may also cause delirium through acetylcholine because it acts through D 2 receptors and reduces acetylcholine levels.
Opiates also cause delirium as they are known to reduce acetylcholine and increase dopamine.
Madan M. Kwatra, Ph.D., presented biochemical information on the enzymes and receptors involved in the function of acetylcholine and how the various components of the cholinergic system are affected with age and anesthetics. Muscarinic receptors, a key target through which acetylcholine produces its action, become desensitized with age. Further, anesthetics are known to disrupt muscarinic receptor-G protein coupling. Whether the cholinergic system of elderly patients is more susceptible to the detrimental effects of anesthetics is an important question that needs to be addressed. Lively discussions following the talks identified three key problems.