New Study Explores Memory Loss and Awakening After Anesthesia

General anesthesia is supposed to induce unconsciousness resulting in amnesia. Amnesia is the absence of both conscious and subconscious thoughts.

Dr. Michael Fettiplace, at the University of Illinois Chicago, and colleagues discovered in mice that it may be feasible to distinguish between awakening from anesthesia and memory resumption. The discovery allows researchers to better understand how anesthetic works, which could lead to better patient care.

However, suppose those two components could be separated and a patient could be awakened from the sleep phase of anesthesia while their brain is still blocked from generating memories. Sedation has hazards, such as breathing problems, thus it may be beneficial to quickly pull patients out of sedation following surgery while delaying their capacity to develop memories until all potentially unpleasant stages, such as breathing tube removal, are completed.

Fettiplace, assistant professor in the College of Medicine and lead author on the study said "Many people thought the loss of memory was due to the fact that you were asleep, or de-aroused", but this is not the case.

Modern anesthetic has made it feasible to undertake complex surgeries and diagnostic tests on patients with more confidence, resulting in substantial medical achievements. For a long time, it was assumed that general anesthesia (GA) had a transitory, reversible impact on the central nervous system (CNS), which returned to its natural form once treatment was stopped. ^[1]

Memory impairment and impaired learning ability are the most common clinical manifestation of POCD (Postoperative cognitive dysfunction). ^[2]

The researchers wanted to check if the animals, now awake, could correctly perform the memory challenge. They started by assigning the animals a task that required them to use their short-term memory to find food then sedated them and gave each rat a stimulant, which is a medicine widely used to treat ADHD. They discovered that they couldn't.

The study's findings also suggest a strategy to accelerate a patient's awakening from anesthesia. Presently  no reversal medicine for anesthesia exists; instead, doctors wait for the patient to metabolize the drug, which gradually wears off. However, there are times when it would be beneficial to revive a patient more quickly.

Conclusion

Research suggests that certain anesthetics can impair memory formation, particularly emotional and spatial memories. Further studies are needed to understand the underlying mechanisms and develop strategies to minimize memory loss associated with anesthesia.

References:

1.Wu L, Zhao H, Weng H, Ma D. Lasting effects of general anesthetics on the brain in the young and elderly: “mixed picture” of neurotoxicity, neuroprotection and cognitive impairment. J Anesth. 2019;33:321–35.

2. Rundshagen I. Postoperative cognitive dysfunction. Dtsch Arztebl Int. 2014;111:119–25. doi: 10.3238/arztebl.2014.0119.

(Input from various sources)

(Rehash/Dr. Richa Gupta/MSM)