• 17 to 43 percent of patients may have cognitive problems such as memory and executive functions that typically last for up to two weeks. However, delirium in adults over 65 can last for several months.
• Some studies have shown that the risk of long-term cognitive damage and post-op delirium is highest for those who already have underlying cognitive vulnerabilities, such as Alzheimer’s or mild cognitive impairment.
• A small percentage of patients have reported traumas from recalling some experience of their medical procedure during general anaesthesia.

In 2011, renowned anesthesiologist Emery Brown began using EEG to track patients’ brain waves.EEG records the electrochemical activity between communicating neurons in the brain. 

During general anaesthesia, you can see, based on the patterns on the EEG monitor, how unconscious someone is, and you can dose your drugs accordingly. But testing whether EEG monitoring helps patients go under and recover better has produced mixed results.

Understanding how patients wake from anaesthesia and under what circumstances they struggle could also help scientists with how to treat disorders of consciousness, including coma. 

Researchers can use general anaesthesia to control the transition into and out of unconsciousness. Like anaesthesia, a coma seems to alter essential communication between different brain networks.

Researchers already use anaesthesia to test potential coma therapies. For example, Ritalin, often prescribed for ADHD, has been found to bring rats back to consciousness after general anaesthesia.