Study finds no link between surgical anaesthesia and MCI
A Mayo Clinic study of people who received anaesthesia for surgery after age 40 found no association between the anaesthesia and development of mild cognitive impairment later in life. Mild cognitive impairment (MCI) is a stage between the normal cognitive decline of aging and dementia. The findings are published in the February issue of Mayo Clinic Proceedings.
Elderly patients can develop delirium after anaesthesia and surgery, but it usually resolves within days or weeks. Researchers have been studying whether surgical anaesthesia is associated with more prolonged cognitive impairment.
“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 anaesthesia for surgery and the development of mild cognitive impairment in these patients,” said senior author David Warner, a Mayo Clinic anaesthetist.
A previous Mayo study found that older patients who receive anaesthesia are no more likely than others to develop dementia.
In the current study, researchers analysed detailed patient information from the Mayo Clinic Study of Aging and the Rochester Epidemiology Project.
The study included people who were ages 70 to 89 and cognitively normal as of October 2004; their mean age was 79, and there were almost equal numbers of men and women. They were evaluated every 15 months. Of 1731 people studied, 85 per cent had at least one surgery requiring general anaesthesia after age 40; 31 per cent developed mild cognitive impairment during the study evaluation period, but it was not found to be linked to their anaesthesia exposure.
The researchers noted that while exposure to anaesthesia for surgery after age 40 wasn’t associated with mild cognitive impairment, they couldn’t exclude the possibility that surgical anaesthesia after age 60 might be, particularly in vascular surgery patients.
“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,” said Warner, adding that more research is needed.
Mayo researchers are also studying the effects of anaesthesia in young children. At that other extreme of age, they are seeing some associations between surgical anaesthesia exposures and some problems with learning and memory later in life.
“Because of the associations that we’ve seen, there is more concern in the young than the old, and it will require quite a bit more research to find out what is happening with the children, and if there is a problem, how we can best address it,” said Warner. “But for the moment, there is little clinical evidence that anaesthesia itself leads to cognitive decline in the elderly – although more research is needed.”