Following surgery, loss of cognitive abilities and problems with thinking, memory, attention, problem solving and language are regularly reported in older people. This 'post operative cognitive decline' syndrome was experienced by the father of OurAlzheimer's sharepost blogger Carol Bradley Bursack. She has written a lot about the adverse effect surgery had on her father and the problems his dementia had on him and her family. The question is what caused his decline? Was it the anesthetic drugs or the surgery that caused his (and others) dementia? Certainly Carol, like many other caregivers, time the onset of Alzheimer's disease to the time of his surgery.
Researchers led by Roderic Eckenhoff, MD from the Perelman School of Medicine at the University of Pennsylvania, used mice with human Alzheimer disease genes and subjected them to either anesthesia alone, or anesthesia and abdominal surgery. They found a number of interesting things:
- That the mice who had undergone surgery showed a lasting increase in Alzheimer's pathology primarily through brain inflammation.
- That mice not altered genetically showed no changes as the result of the surgery or anesthesia.
- There was a clear and persistent decrease in learning and memory caused by surgery as compared with anesthesia in the transgenic mice.
- That significant cognitive impairment persisted for at least 14 weeks after surgery compared to controls receiving anesthesia alone.
A transgeneic mouse is a genetically modified mouse that has had its genome altered through the use of genetic engineering techniques. Genetically modified mice are commonly used for research or as animal models of human diseases, in this case Alzheimer's. Because of this the reseach findings "may not translate well to people" says team member and neuroscientist Maryellen Eckenhoff, PhD.
It also has to be remembered that AD mice used, like all current mouse models of Alzheimer disease, more closely resemble the situation in familial Alzheimer's disease. As we know familial AD only constitutes a small minority of patients. Dr Eckenhoff says that we do not yet know whether results from AD mouse models will represent patients who eventually get late-onset, or "sporadic" Alzheimer disease.
The transgenic mouse makes a big contribution to our knowledge of human disease and helps screen new drugs. It is hoped they will help us treat Alzheimer's more effectively in the future.
This study was funded by the National Institute on Aging (Grant AG031742) and the Austin Lamont Endowment Fund.
Modulation of Murine Alzheimer Pathogenesis and Behavior by Surgery
Tang, Junxia X.; Mardini, Feras; Janik, Luke S.; Garrity, Sean T.; Li, Rosie Q.; Bachlani, Gulnaz; Eckenhoff, Roderic G.; Eckenhoff, Maryellen F.
Annals of Surgery. 7 September 2012 doi: 10.1097/SLA.0b013e318269d623