According to a recent study, major surgery triggers various patterns of cognitive alterations depending on the absence or presence of Alzheimer's pathologies.

An elderly Sardinian man
(Photo : Jean Bajean / Wikimedia Commons)

What is Alzheimer's Disease?

According to the National Institute on Aging, Alzheimer's disease is, unfortunately, an irreversible brain disorder that slowly eats away memory, thinking capacities, and in the long run, the ability to execute simple tasks. 

Depending on the type of Alzheimer's disease, symptoms can show in people as early as 30 years old to mid-60s. The most common cause of the disease in older adults is dementia.

In a report by Alzheimer's Association, there is an increase in Americans living with Alzheimer's disease. Roughly 5.8 million Americans from the ages of 65 and up are diagnosed with Alzheimer's dementia in 2020. With two-thirds of patients are women.

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Studying the Relationship of Major Surgery and Alzheimer's Disease

A recent study published in the Journal of Alzheimer's Disease headed by researchers from the Marques de Valdecilla-IDIVAL University and the University of Bonn Medical Center suggests that major surgery promotes the acceleration of Alzheimer's disease.

AD is known as one of the greatest public health challenges. From the appearance of the first lesions in the brain, it can take up to 20 years before it clinically manifestation. Today, modern science can detect the presence of initial lesions with biochemical markers.

Carmen Lage from the Neurology Service and Centro de Investigacion Biomedica says, "Although the phenomenon of cognitive deterioration after surgery has been known for a long time, there are few studies that relate it to AD (Alzheimer's disease). In the clinic, the patient's relatives frequently tell us that memory problem begins after a surgical procedure or a hospital admission. This posed the following question: is this just a recall bias or has surgery triggered the appearance of symptoms?"

Researchers administered cognitive tests to healthy 65-year-old individuals before undergoing orthopedic surgery. They obtained CSF samples to determine amyloid-B levels during anesthesia. The same tests were administered nine months later after surgery.

The results showed that half of the patients' cognitive levels worsened compared to scores before surgery. Individuals with altered amyloid-B levels showed patterns compatible with AD, predominantly memory problems

Lage explains, "Prior surgery, the memory test scores of the subjects with normal amyloid-B levels were indistinguishable from those with normal levels. Yet after surgery, they were significantly worse."

These results led researchers to conclude that major surgery in fact triggers different patterns of cognitive alterations based on the absence or presence of Alzheimer's pathological change.

Dr. Pasucal Sanchez-Juan, a co-author of the study, expresses concerns that with the technological advancements of society more elderly individuals are undergoing various procedures.

Despite pre-surgery assessments of respiratory and cardiac levels potential consequences of cognitive alterations are not usually determined.

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