Does Major Surgery Boost the Risk For Developing Dementia?

Anesthesiologists have been debating the effects of surgical anesthetics on brain function for years. Some research suggests that cognitive dysfunction is a temporary consequence of anesthesia. Other studies indicate that the brain problems may last longer. A new study published in the Journal of the American Geriatrics Society (May 16, 2026) reports some startling statistics about older adults undergoing major surgery: a surprisingly large number experienced an increased risk for developing dementia. Only about one-fourth “remained stable” after major surgery.

How Does General Anesthesia Impact the Risk of Developing Dementia?

As people get older the body starts to break down. Joints fail, for example, and people need knee or hip replacements. Heart valves may become calcified and require surgery. Then there is hernia repair or gallbladder surgery. Sometimes the surgery is crucial, even life saving. Other times, though, surgery may be discretionary.

The introduction to a recent article in the Journal of the American Geriatrics Society (May 16, 2026) points out that the United States population is aging:

“Many of these older adults will face the possibility of undergoing major surgery, a decision which requires balancing the potential benefits of surgery with the possibility of poor outcomes, such as cognitive and functional decline [2]. Older patients, especially those who may already be experiencing some degree of decline, may want to consider their predicted cognitive trajectories following surgery.”

Why would surgery lead to an increased risk for developing dementia?

The authors of this study note in their introduction:

“The anesthesia community has reported ‘postoperative neurocognitive disorders (PND),’ which have been linked to
higher mortality after surgery as well as persistent cognitive decline many years after surgery.”

The distinguished investigators from Harvard, Brown, Beth Israel Deaconess Medical Center and other institutions analyzed data from 560 participants. The patients were carefully screened before and after surgery and many were followed for up to six years.

We found the results alarming with:

• “15% experiencing severe cognitive decline
• “59% experiencing slight decline
• “26% with no decline over 6 years

The authors note:

“Our results are consistent with previous literature describing the incidence and risk factors for PND [postoperative neurocognitive disorders].

“Our study confirms and extends this previous literature. First, while most of these studies considered cognition up to 1 year after surgery, we had extended follow-up of cognitive testing out to 6 years after surgery.”

They conclude:

“Older age, lower baseline cognitive score and the development of postoperative delirium were three independent factors identifying individuals who fell into the severe cognitive decline group.”

Other Research Related to Surgery and the Risk for Developing Dementia:

A  study from the Mayo Clinic indicated that older adults undergoing surgery with general anesthesia experienced some measure of cognitive decline (British Journal of Anaesthesia, online March 10, 2020). At the same time, the cerebral cortex became thinner.

The scientists reported that finding in 2019(British Journal of Anaesthesia, Dec. 2019). At that time, they reported no link between prior surgery with general anesthesia and brain infarcts. These tiny blood clots in the brain can cause cognitive impairment, although they are different from Alzheimer disease. Still, older adults contemplating surgery should feel somewhat reassured that there is no connection with infarcts.

Cognitive decline is worrisome.

Reassuring News:

The authors of the study published in the British Journal of Anaesthesia reassured their medical colleagues that surgery with general anesthesia is not related to Alzheimer disease. They do acknowledge, however, that such procedures may be linked to modest cortical thinning in the brain and slightly accelerated cognitive decline over time.

Less Reassuring News:

Irish researchers were less optimistic.

The results of their research in the Annals of Surgery (April, 2017) were worrisome:

“There is a hidden epidemic of cognitive dysfunction in the perioperative setting. Up to 40% of patients who develop postoperative delirium (POD) never return to their preoperative cognitive baseline. POD can lead to postoperative cognitive dysfunction (POCD), a more prolonged cognitive impairment associated with longer length of hospital stay and cost, premature withdrawal from the workforce, and greater 1-year mortality.”

Developing Dementia and/or Cognitive Decline After High-Risk Surgery:

The authors of this study in the Annals of Surgery (Jan. 1, 2022) report:

“In this nationally representative study using a robust longitudinal data source, we found that older adults undergoing high-risk surgery are at higher risk of functional and cognitive decline, and that a serious postoperative complication exacerbates this risk. In addition, increasing age, frailty, number of comorbid conditions, and worse baseline functional and cognitive statuses predicted a significantly higher risk of functional and cognitive decline, which translated to poorer long-term survival and increased healthcare utilization. With the aging population and an increasing number of older adults undergoing surgical procedures, these data have important implications.”

Take Home Message Here!

There are times when surgery is absolutely essential. Having undergone emergency abdominal surgery myself for an intestinal blockage I can attest to the fact that surgery can be life saving. It can also restore function. I had a hip replacement when my old hip became “bone on bone.” I can now play tennis again thanks to that surgical intervention.

There may be times, however, when a surgical intervention is “discretionary.” That is to say, it might not always be necessary to save a life to make a big difference in life quality. In those instances it is important to have a frank discussion with several healthcare providers. The surgeon should be consulted, of course, but you may also want an opinion from a trusted non-surgical medical advisor.

The authors of the latest research linking major surgery to a risk for developing dementia also point out that 26% of the patients:

“…experienced cognitive improvement 1-month after surgery and no significant decline over the subsequent 6 years.”

They add that:

“…patients who benefitted cognitively from surgery through improved functional and exercise status, is uncertain. However, it is important to note that many older adults thrive, and do not decline, after major surgery”

Some readers have reported experiencing brain fog, insomnia or confusion following surgery with anesthesia. You can read their stories here. If you have had surgery with general anesthesia and want to share your experience, add your comment below. We would be grateful if you were to share this article with friends and family.