Surgery no matter how routine a procedure always has its risks, whether from the condition being treated or the process itself, but scientists have discovered a possible link between the general anesthesia used in most surgeries and the onset of dementia. A recent article in Scientific American explored whether we should be really concerned about going under the next time we need surgery.

Roni Jacobson, author of "Can General Anesthesia Trigger Dementia?" interviewed Sanfra Anastine, a woman who loses some of her cognitive abilities every time she ends up on the operating table. The first time was when she was 42. After surgery she found that she couldn't speak. Luckily it only lasted 12 hours. However when she was 56 and had to undergo general anesthesia again, this time it took three months for her to regain her speech and still to this day a little bit of forgetfulness lingers. Now at 61, she worries about what will happen if she needs surgery again.

Roderic Eckenhoff, an anesthesiologist at the University of Pennsylvania, told Jacobson that it is common for elderly patients to go through "postoperative cognitive decline" after surgery. Typically it manifests as a grogginess that leads to deficits in memory and attention. However these aftereffects of surgery usually dissipate after a few weeks.

Anastine however had her first episode at the age of 42 and still has lingering effects after her second surgery. Could there be more going on here?

Surprisingly while putting patients under general anesthesia is a common surgical practice, there are still a lot of unanswered questions about how it actually works. The most common explanation of how it functions is that the "drug molecules bind to sites on the surface of neurons and deactivate different proteins important in a wide range of cognitive functions, including sleep, attention, learning and memory."

More recent research however points to the idea that these drug molecules might not stop there, but also affect the communication networks between the different regions of the brain.

According to Maria Lioudyno, a neuroscientist at the University of California, Irvine, the molecules "can trigger other mechanisms that have nothing to do with the anesthesia itself including processes that may be linked to neurodegeneration."

While most research does not indicate that a patient's chance of developing dementia, a more permanent loss of cognitive abilities, will increase after receiving general anesthesia, some experiments on the cellular level have suggested the possibility that anesthesia can boost the development of proteins considered markers of Alzheimer's disease if they are already present.

Eckenhoff at the University of Pennsylvania also found links between use of anesthetics and dementia. In studies done in 2004 and 2007, he and his fellow researchers studied the effects of the inhaled drug on mice and they too discovered the buildup of a protein thought to be a marker of Alzheimer's. In their studies it was amyloid beta and in other experiments it was a protein called tau that was found.

Despite all these connections though, Eckenhoff still believes that there is no cause for alarm because the effects on the brain so far are found to be minimal. A 2013 Mayo Clinic study which looked at the medical records of patients with dementia and compared them to a group who were not suffering from the neurological disorder found that both groups had experienced similar rates of exposure to anesthesia, indicating that it is not a risk factor.

But what about Anastine and others like her? Some people definitely seem to have a stronger reaction to anesthesia. Robert Whittington, professor of clinical anesthesiology at Columbia University Medical Center, has found that patients who are genetically predisposed to develop dementia and those who have other health conditions like heart disease or diabetes are more susceptible to the drug.

Work is already being conducted on ways to identify which patients are more prone to developing dementia as well as ways to make surgery safer for them. Both more targeted anesthetics and supplemental drugs are being looked at, but in the meantime Eckenhoff cautions susceptible patients to refrain from any cosmetic or elective surgery.

[Scientific American]