Does Anesthesia Increase Surgery Dementia Risk?

Published on Aug 11, 2017

This morning’s study is near and dear to my heart. When I was a medical student, my father broke his hip and needed surgery. After surgery in the hospital where I was training, he experienced severe postoperative delirium. It was epic “sundowning,” which foreshadowed his upcoming dementia and slow descent into his own personal hell at the hands of a disease called Diffuse Lewy body (DLB). Maybe that’s where I got my aversion to major surgical procedures. Not sure, but it is great to see more research this past decade on the effects of general anesthesia on patients.

What Is Postoperative Delirium and Dementia?

Postoperative delirium is characterized by sudden cognitive changes, including disorientation and confusion, following surgery with anesthesia, and it is a very common postoperative complication in older adults. It goes beyond just that normal groggy feeling after surgery. Patients can even experience agitation, lethargy, or a combination of both. The delirium won’t necessarily be present immediately following surgery; it can occur hours and even days later.

The worse form of postoperative delirium is sundowning. This is basically total confusion and fear at night. We all have our built-in, primal fear of the dark rooted in our animal instincts. Sundowning is what happens when all of the tools we use to manage that, like logic (i.e., there’s nothing out there), go out the proverbial window. It’s a huge nightly problem in many a nursing home.

Dementia, or cognitive decline, includes a variety of neurodegenerative diseases of the brain that develop and progress slowly. Some of the more common dementias include Alzheimer’s disease (the most common), vascular dementia, and Huntington’s disease. The second leading cause of dementia is actually the disease my father had, Diffuse Lewy body (which is wildly underdiagnosed). Dementia can be genetic, but it can also develop or get worse when exposed to other things that can damage or destroy our brain neurons. Our feature study suggests that in some patients, general anesthesia may be one of those things.

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Study Review: Postoperative Delirium Linked to Dementia

The new study consisted of 2,014 subjects aged 65 and older who would be undergoing surgery with anesthesia. A variety of tests were performed before surgery to determine cognitive status (normal or existing dementia) and after surgery to detect any postop delirium.

The result? Seventy-four of the subjects experienced delirium following their surgery. As would be expected, subjects who already had dementia did experience a higher frequency of postop delirium. The key finding here, however, was that among the subjects who had a normal cognitive status prior to surgery, nearly 10% displayed dementia at their postop evaluation with the higher number of these also having experienced postop delirium. Researchers concluded that delirium after surgery does increase surgery dementia risk in elderly patients who have a normal cognitive status (no preexisting dementia) prior to the surgery.

Surgery Dementia Risk

The link between surgery and dementia, or cognitive decline, isn’t a new one. Studies have clearly shown the following risks for dementia following surgeries using anesthesia:

Patients who already have or are at a risk dementia are at a greater risk of further cognitive decline following surgery.
Patients who are sicker (e.g., diabetes, high blood pressure, prior stroke, etc.) and exposed to more anesthesia have an increased risk of dementia.
The more surgeries a patient has, the greater the surgery dementia risk.
Dementia risks may increase depending on the type of anesthesia used.

Other Dementia Risks

Dementia rates generally have been rising with each passing year, and with over five million Americans affected, surgery dementia risk isn’t the only concern. Dementia has been associated with toxins released from car exhaust in which one study showed an increased risk of Alzheimer’s dementia in those living closer to heavy-traffic areas.

Diet soda has, unfortunately, become a mainstay in the U.S., despite the fact that we know artificial sweeteners have been linked to a variety of problems, including Alzheimer’s dementia. Another risk for dementia is living with unaddressed chronic pain. In addition using nonsteroidal anti-inflammatory drugs (NSAIDs) for pain and inflammation has been linked to Alzheimer’s dementia. While this list certainly isn’t exhaustive, and, truth be told, we’re probably just skimming the surface of all the dementia risks that will likely be revealed in the future, it gives you an idea of what you can do to start eliminating or mitigating your dementia risk.

The upshot? Did that hip surgery cause my dad’s dementia? My personal opinion is that it was the match that lit the bonfire, but that his genetics and his lifestyle combined to bring the wood and the gasoline. In the meantime, we all need to be careful not to undergo big surgeries we don’t need, especially as we get older. While that couldn’t be prevented in my father, it can usually be prevented with big surgeries, like joint replacements. So be careful, anesthesia isn’t always without side effects!