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   Why anesthetics cause prolonged memory loss   
   Date:   
   November 3, 2014   
   Source:   
   University of Toronto   
      
      
   Researchers at the University of Toronto's Faculty of Medicine have shown why   
   anesthetics can cause long-term memory loss, a discovery that can have serious   
   implications for post-operative patients.   
      
   Until now, scientists haven't understood why about a third of patients who   
   undergo anesthesia and surgery experience some kind of cognitive impairment --   
   such as memory loss -- at hospital discharge. One-tenth of patients still   
   suffer cognitive    
   impairments three months later.   
      
   Anesthetics activate memory-loss receptors in the brain, ensuring that   
   patients don't remember traumatic events during surgery. Professor Beverley   
   Orser and her team found that the activity of memory loss receptors remains   
   high long after the drugs have    
   left the patient's system, sometimes for days on end.   
   Animal studies showed this chain reaction has long-term effects on the   
   performance of memory-related tasks.   
      
   "Patients -- and even many doctors -- think anesthetics don't have long-term   
   consequences. Our research shows that our fundamental assumption about how   
   these drugs work is wrong," says Orser, a Professor in the Departments of   
   Anesthesia and Physiology,    
   and anesthesiologist at Sunnybrook Health Sciences Centre.   
      
   In the study -- led by PhD candidate Agnes Zurek -- the team gave healthy male   
   mice a low dose of anesthetic for just 20 minutes and found that receptor   
   activity was increased for a week afterwards. These results suggest the same   
   effect can impact a    
   patient's learning and memory during a time when they are receiving critical   
   information about their care.   
      
   "There's a lot going on after surgery, which can alter our ability to think   
   clearly. Loss of sleep, new environments and medications can all impact a   
   patient's mental function. Anesthetics likely compound these issues," says   
   Orser.   
      
   She recommends physicians and family members carefully monitor patients after   
   surgery for any signs of memory loss. "Patients should write everything down   
   or have a second pair of ears with them after surgery. For high-risk groups,   
   physicians need to    
   inform patients about these possible side effects and help manage the impact   
   on recovery and overall health," says Orser.   
      
   The likelihood of a patient experiencing cognitive impairment depends on their   
   age, health, type of surgery and the anesthetic, with chances increasing for   
   more intricate procedures. The incidence is highest in the elderly or those   
   undergoing major    
   surgery such as cardiopulmonary bypass.   
      
   "Anesthetics don't put you to sleep -- they induce a pharmacological coma. We   
   shouldn't take these drugs lightly," Prof. Orser cautions.   
      
   Orser and her team are looking at drugs that can stop the receptors and   
   restore memory loss. While they are still in the early stages of research,   
   they say some of the drugs show very promising results in animal studies.   
   The study was published in the Journal of Clinical Investigation.   
      
   Story Source:   
   The above story is based on materials provided by University of Toronto. The   
   original article was written by Suniya Kukaswadia. Note: Materials may be   
   edited for content and length.   
      
   Journal Reference:   
   Agnieszka A. Zurek, Jieying Yu, Dian-Shi Wang, Sean C. Haffey, Erica M.   
   Bridgwater, Antonello Penna, Irene Lecker, Gang Lei, Tom Chang, Eric W.R.   
   Salter, Beverley A. Orser. Sustained increase in α5GABAA receptor function   
   impairs memory after anesthesia.    
   Journal of Clinical Investigation, 2014; DOI: 10.1172/JCI76669   
      
   Cite This Page:   
   MLA APA Chicago   
   University of Toronto. "Why anesthetics cause prolonged memory loss."   
   ScienceDaily.    
   ScienceDaily, 3 November 2014.    
      
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