March 9, 2021
Having a major surgical procedure may speed the onset of Alzheimer’s disease or worsen its progression, researchers report. The findings build on earlier research showing that the stress and disruption of major illness and hospital stays can take a toll on the brain.
Doctors and other health care workers are familiar with the toll that hospital stays can take on patients’ mental states and even have a name for it: “hospital delirium.” It is particularly common in older patients and in those with dementia, who may experience an exacerbation of symptoms such as hallucinations, agitation and aggression.
The stress and anxiety of undergoing medical procedures in a foreign environment, along with disrupted sleep, painful medical procedures, infections and new medications including the anesthetics used for general anesthesia, likely contribute to the onset of hospital delirium. Afterwards, older patients who experience delirium are more likely to be moved to a nursing home or rehabilitation center.
“Although the phenomenon of cognitive deterioration after surgery has been known for a long time, there are few studies that relate it to Alzheimer’s disease,” said Carmen Lage, the lead researcher of the current study. “In the clinic, the patient’s relatives frequently tell us that memory problems began 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 the symptoms in a previously affected brain?”
For the present study, the researchers studied patients undergoing surgery at the Marqués de Valdecilla-IDIVAL University Hospital in Spain. All were older than 65, but none of them had dementia.
They underwent clinical tests to detect levels in the spinal fluid of beta-amyloid, the toxic protein that builds up in the brains of those with Alzheimer’s disease. They also underwent cognitive tests of memory and thinking skills before their surgery, and again nine months later.
The researchers found that about half of the patients undergoing surgery showed declines in cognitive skills after their hospital stays. But those who had high levels of beta-amyloid, consistent with an increased risk for Alzheimer’s disease, fared the worst on measures of memory.
“Before the surgery, the memory test scores of the subjects with abnormal beta-amyloid levels were indistinguishable from those of subjects with normal levels,” said Dr. Lage. “Yet after surgery, they were significantly worse.” The memory declines, she noted, were “consistent with the first clinical manifestations of Alzheimer’s disease, and therefore associated with greater probabilities of progression to dementia.”
Earlier research has shown that hospital stays can be particularly damaging for people with Alzheimer’s disease. In those with dementia, a hospital stay greatly increases the risk of further decline, including the need to enter a nursing home. About half of people with dementia who are hospitalized also develop delirium, which further increases the risk of decline and death.
While hospital stays are often needed to treat a variety of medical conditions, the findings confirm earlier concerns about the dangers of hospitalization, particularly for those with dementia. They also underscore the importance for all of us of avoiding hospitals whenever possible, particularly in this time of Covid.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Lage, Carmen; Gonzalez-Suarez, Andrea; Alcalde-Hierro, Mari Puerto; et al: Major Surgery Affects Memory in Individuals with Cerebral Amyloid-β Pathology. Journal of Alzheimer’s Disease, January 19, 2021