Elderly patients undergoing anesthesia and surgery frequently suffer from postoperative cognitive dysfunction (POCD) and postoperative delirium (PD). The cause of these entities is unknown;specifically it is unclear what part the anesthetics play in the development of POCD and PD. We hypothesize that elderly patient's cognitive capacities recover more slowly after receiving general anesthesia, perhaps because they have more limited cognitive reserve. A more prolonged recovery would confound diagnoses of POCD and PD and potentially puts patients who are discharged on the day of surgery at risk of not understanding postoperative instructions. The trajectory of postoperative cognitive recovery has never been explored and elderly participants have been explicitly not included in any type of emergence research. To explore this vital area we propose to study young and elderly volunteers with a combination of two state of the art neuropsychological tests (postoperative quality of recovery scale and the NIH Toolbox) and magnetic resonance imaging. Starting from baseline, we will determine multiple cognitive domains and resting state networks, treat the volunteers with general anesthesia, and then explore the recovery of the cognitive domains and alterations in functional networks. The data acquired in this project will have both clinical and theoretical relevance. Apart from distinguishing immediate drug effects from POCD and PD, characterization of the trajectory of cognitive recovery in the elderly could affect changes in clinical practice vis a vis the criteria we employ to determine, for example, hospital discharge in this population. Currently many elderly patients are (perhaps inappropriately) sent home on the day of surgery. Furthermore, characterization of the trajectory of recovery in this population would enable us to better educate our patients and those who help care for them as to the proper expectations and time course for their recovery from anesthesia. Most fundamentally, the trajectory at which various patients recover from anesthesia is the most unappreciated confounding factor in this debate on the direct and indirect effects of anesthetic drugs. The effects of the anesthesia itself are theoretically (and as we propose here, practically) separable from those due to surgery, by studying the former in the absence of the latter we can delineate the trajectory of cognitive recovery from anesthesia itself, developing an understanding that is currently lacking and yet necessary to understand POCD and PD in general.
The data acquired in this project will have both clinical and theoretical relevance, helping to distinguishing immediate effects of anesthesia from prolonged cognitive impairment and postoperative delirium. The information could affect how we determine when elderly patients are discharged from the hospital to avoid readmission. Most fundamentally, the trajectory at which various patients recover from anesthesia is the most unappreciated confounding factor in this debate on the direct and indirect effects of anesthetic drugs.