Surgery may be an accelerator of Alzheimer’s disease.
Is surgery linked to memory loss?
IT IS NOT RARE for my older patients to suffer from memory loss following major surgery or hospital admission. Still, the conclusions of a recently published study stopped me in my tracks. Researchers at Marqués de Valdecilla-IDIVAL University Hospital, in collaboration with researchers at the University of Bonn Medical Center, propose that major surgery is a promoter of Alzheimer’s disease.
Alzheimer’s disease is one of our most significant public health challenges. It is the most common cause of dementia and is a leading source of morbidity and mortality in the aging population. In the United States in 2011, 4.5 million individuals over the age of 65 had Alzheimer’s. Dementia is second to heart failure as a leading cause of mortality, accounting for approximately 19 percent of deaths.
From the time Alzheimer’s-associated lesions in the brain develop, it can take up to 20 years before the appearance of symptoms. Scientists look for biochemical markers such as amyloid-β. This substance is one of the main proteins that build up in the brains of those with Alzheimer’s.
We know that the frequency of amyloid-β deposits in healthy people increases with age. By 65 years of age, we have a one in three chance to have this brain-based protein. For those who carry amyloid-β, we don’t fully understand why the rate of disease progression varies among individuals. Why do some with amyloid-β have rapid progression to dementia, while others have slower progression?
The researchers recognized that some experienced a cognitive decline after surgery but that few studies examine it relative to Alzheimer’s dementia. They had an innovative idea: Administer cognitive tests to healthy subjects over age 65 before orthopedic surgery. During the surgery (while patients were unconscious), scientists obtained spinal fluid samples to check for amyloid-β levels. The subjects repeated the same cognitive tests nine months later.
Research findings: Is surgery linked to memory loss?
Half of the patients experienced a cognitive decline when comparing after versus before surgery. Those who had altered amyloid-β levels showed a pattern consistent with the onset of Alzheimer’s disease, with significant memory impairment.
Study author Carmen Lage offers these observations: “Before surgery, the memory test scores of those with abnormal amyloid-β levels appeared indistinguishable from those of subjects with normal levels, and yet after surgery, they were significantly worse. These results lead us to this conclusions:
- Surgery can set off different patterns of cognitive changes, depending on the previous presence or absence of Alzheimer’s pathological changes.
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