A new study using people who received anesthesia for surgery after age 40 revealed no association between the administration of anesthesia and the patient’s development of permanent cognitive impairment, including developing such problems later in life.
The Mayo Clinic study defines mild cognitive impairment as a stage between the normal cognitive decline of aging and dementia. The findings published in the February issue of the medical journal Mayo Clinic Proceedings likely brings relief to millions of over-40 Americans facing surgery. The study concedes elderly patients may develop delirium after anesthesia and surgery that usually resolves within weeks, however the study cleared anesthesia as the culprit in long-lasting and latent development of mild cognitive decline.
“We looked at a group of patients who have been followed here in Olmsted County, where we have detailed information about their cognitive function as they age. The bottom line of our study is that we did not find an association between exposure to anesthesia for surgery and the development of mild cognitive impairment in these patients,” says senior author David O. Warner, M.D., a Mayo Clinic anesthesiologist.
The new study paralleled a former study by the Mayo Clinic that also found no evidence that older patients who receive anesthesia are more likely than younger patients to develop any form of dementia.
Results of the current study were released by researchers after analyzing patient information from the Mayo Clinic Study of Aging and the Rochester Epidemiology Project. The study included people between ages 70 and 89 found to be cognitively normal as of October 2004; their mean age was 79, and there were almost equal numbers of men and women. The subjects received data evaluation once every 15 months. There were 1731 people in the study and 85 percent had at least one surgery that required general anesthesia after age 40. While 31 percent of those tested did experienced mild cognitive impairment during the study evaluation period it was not linked to the administration of anesthesia.
While the study cleared anesthesia as a cause of mental decline in surgical patients over 40, the Mayo Clinic researchers say those over 60 years of age may be prone to develop mild cognitive impairment from the use of anesthesia, particularly patients who suffer from vascular problems.
“That may not be surprising, because there is increasing evidence that some of the problems that we see with cognition in the elderly may be caused by vascular problems that cause stroke and other sorts of problems like that,” Dr. Warner says, adding that more research is needed.
Mayo researchers are also studying the effects of anesthesia on young children. At that other extreme of age, they are seeing some associations between surgical anesthesia exposures and problems with learning and memory later in life, Warner says, adding more study is needed.
