By Varshini Chellapilla
A common question asked of physicians and surgeons is whether anesthesia, generally given during surgeries, is associated with a risk of developing Alzheimer’s disease or other related dementias (ADRD) in the future.
“It’s not an unreasonable notion that anesthesia would affect brain health,” Dr. Wolk said. “Anesthesia has many effects on the brain, and surgery itself is associated with all sorts of systemic changes in the body and brain.”
A new study conducted by Penn Memory Center Co-Director and Alzheimer’s Disease Research Center Director David Wolk, MD, in collaboration with colleagues in the Perelman School of Medicine and The Wharton School, observed elderly patients who were exposed to anesthesia during an appendectomy, a surgical procedure performed to remove the appendix, and then followed post-operation to determine if there was an association between anesthesia and development of clinical Alzheimer’s disease. The study, titled “Alzheimer’s Dementia After Exposure to Anesthesia and Surgery in the Elderly,” was published in the Annals of Surgery in the November 2020 issue.
“Prior work suggested that anesthesia may play a role in promoting or accelerating Alzheimer’s disease. There is also some thinking that surgery itself also may have negative effects on cognition,” Dr. Wolk said. “This study specifically examines this issue, at least in presumably cognitively normal older adults, and what their risk of developing dementia after a surgical event is.”
The team of Penn researchers found that there was no indication suggesting that anesthesia in elderly patients undergoing appendectomies increased the risk for Alzheimer’s disease or other related dementias.
The study is a natural experiment, involving the examination of nearly 55,000 Medicare patients and over 270,000 other similar patients used as controls. The patients were matched according to similar medical conditions and followed from five to 15 years. According to Dr. Wolk, this study is the first systematic large-scale study of potential associations between anesthesia and dementia.
Anesthesia is a medical treatment, usually administered during surgical procedures, that prevents the body from feeling pain. The anesthetic drugs can render patients unconscious during surgery or simply numb part of their body.
An appendectomy was chosen because it is a common surgical procedure done to treat appendicitis, which is a condition that can occur in older patients randomly without known associations with dementia risk that could confound the results.
“The bottom line, really, is that there was actually no evidence whatsoever of an increased rate of dementia or cognitive impairment in the group that had an appendectomy versus the group that didn’t,” Dr. Wolk said.
Co-authors of the study include Jeffrey H. Silber, MD, PhD, director of the Center for Outcomes Research at The Children’s Hospital of Philadelphia; Siddharth Jain, DrPH, MBBS, MPH; Paul Rosenbaum, PhD, a professor of statistics at The Wharton School; Roderic Eckenhoff, MD, an anesthesiologist at Penn Medicine; and Lee Fleisher, MD, a Penn professor of anesthesiology and critical care serving as the chief medical officer and director of the Center for Clinical Standards and Quality for the Center for Medicare and Medicaid Services.
It is important to note that the study does not state that all surgeries and all types of anesthesia do not have an association with the likelihood of developing dementia in the future. Additionally, the study did not focus on the potential effects of anesthesia on patients already with Alzheimer’s disease and other related dementias (ADRD) specifically in regards to their disease.
“Theoretically, a larger surgery or maybe a specific anesthesia could have an effect on people, but I think it’s a pretty comforting result that whatever is going on is not a real strong driver of development of dementia in older adults,” Dr. Wolk said. “We also often get a question about whether this will speed up the course of the disease in patients who already have ADRD, and I don’t think we can say that with clarity because this study looked at cognitively normal older adults.”