Anesthesia and Surgery Probably Not Bad for Aging Brains

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There have been rumblings in the medical community in the last several years questioning the safety of anesthesia, especially when it comes to the brain. But because the cause of many dementia, one of the most common brain disorders in older adults, still remains unknown, researchers and scientists have gone to work looking for possible causes. Some studies have shown that anesthesia and surgery may be linked to cognitive issues and brain disease, but it’s been hard to study these effects in a meaningful way. Now, a study examining twins in Denmark has provided high quality evidence that anesthesia and surgery are unlikely to pose the risks many had feared.

Why were people worried about the brain after surgery?
Aging often brings with it a variety of health issues for our bodies and the brain is no exception. (Here’s your brain protection plan.) The different forms of dementia, such as Alzheimer’s disease, have become increasingly common among older adults as people live longer. In spite of that, doctors and researchers are still uncertain about what exactly causes a person to develop cognitive problems and dementia. There are some situations where the cause is clear: Having high blood pressure or diabetes — diseases which are common in older adults — increases a person’s risk for dementia because they directly damage to the brain. But the cause of other forms of dementia, such as Alzheimer’s or Parkinson’s, still aren’t well understood.

In the search for possible contributors, researchers had wondered about surgery and anesthesia. There were several reasons for this suspicion. First, many cited the stress of surgery as a possible cause since it can lead to widespread inflammation that might damage the brain. Others pointed to anesthetics, both because they act directly on the brain and because animal studies had shown some brain damaging effects in animals exposed to anesthetic drugs for extended lengths of time. Some human studies even showed a possible link, since longer surgeries seemed to be associated with more cognitive problems than shorter surgeries.

Watch: The Memory Cure to Prevent Alzheimer’s Disease

Why question the link between surgery, anesthesia and the brain?
The problem is, not all studies pointed to surgery as the culprit of brain issues. For example, people with heart disease have similar brain issues regardless of whether they’ve had surgery for the disease or not. Another study in colon cancer patients found that cognitive problems in people undergoing treatment for colon cancer was actually better linked to the dose of chemotherapy they were getting than whether or not they’d had surgery. Increasingly, the message seemed to be that people undergoing surgery are probably just more sick, which meant their brains were being hit with more damage, putting them at higher risk for dementia. This research team wanted to figure out once and for all if seniors should be concerned about their brain when going under the knife.

How did the team answer this question in a new way?
The researchers took the unique step of looking at identical twins. Identical twins are genetic clones of each other. They share all of their genes and also often share similar upbringings and similar lifestyles. In the case of this study, looking at twins that either did or didn’t have surgery was as close as the research team could get to what would happen to a person if they did or didn’t have surgery. They recruited about 8,500 identical twins to be a part of their study. Half were under 70 and half were over 70. They then looked at the medical and surgical history of each twin, first comparing them to other twins and then to their own twin. They looked to see how the cognitive abilities and the presence of dementia was different in those who had surgery compared to those who didn’t.

More: Superfoods to Prevent Alzheimer’s and Boost Your Memory

What did the researchers find?
About two thirds of the twins had undergone surgery at some point in their lives. In keeping with past research, twins who had major surgery in the past were more likely to have lower scores on brain function tests than those without surgery, but that effect was extremely small. No difference was seen in those with only minor surgery. But the key to this study was looking at how mental function compared within twin pairs where one twin had had surgery and the other had not. This served as a direct comparison that removed the effects of genes completely. In the 211 pairs of twins that included one post-surgical twin and one twin without surgery, there was no difference between the twins regardless of how long ago the surgery was. It’s this second finding in particular that makes any link between cognitive problems like dementia and surgery or anesthesia very unlikely.

How does this apply to me?
If you’ve been following this news about the brain effects of anesthesia or surgery, you might have questioned the benefits of going under the knife for fear of what would happen to your brain. This research should help put your mind at ease, at least when it comes to the risk of dementia and cognitive issues. With that said, surgery and anesthesia often carry many other, potentially deadly risks and deciding to have surgery isn’t an easy choice. The decision should always take place in partnership with your doctor and the people you love so that you can effectively weigh the risks and benefits and decide what’s right for you.