Summary: Major surgery may trigger distinct patterns of cognitive change depending on whether Alzheimer’s disease–related brain pathology is already present.
Source: IOS Press
A new study published in the Journal of Alzheimer’s Disease, led by researchers at Marqués de Valdecilla-IDIVAL University Hospital with collaborators from the University of Bonn Medical Center, suggests that major surgery can act as a promoter or accelerator of Alzheimer’s disease (AD). The study’s first author is Carmen Lage and the principal investigator is Pascual Sánchez-Juan.
Alzheimer’s disease poses a growing public health challenge. Pathological changes in the brain, including accumulation of amyloid-β protein, can begin decades before clinical symptoms appear. Biomarkers such as amyloid-β measured in cerebrospinal fluid (CSF) allow detection of these early changes. The prevalence of amyloid-β deposits rises with age and can be found in a substantial portion of cognitively normal older adults, but not all individuals with amyloid-β go on to develop clinical dementia. What determines whether an asymptomatic person with amyloid pathology progresses rapidly to dementia, slowly, or remains stable is incompletely understood.
Clinicians often hear from families that memory decline began after a surgery or hospital admission. That observation led the research team to ask whether surgery might unmask or accelerate cognitive decline in people who already have underlying Alzheimer’s pathology. To explore this question, the investigators examined the relationship between CSF amyloid-β levels and cognitive changes after major orthopedic surgery under spinal anesthesia.
The study recruited non-demented adults over age 65 who were scheduled for orthopedic surgery. Participants underwent a neuropsychological assessment before surgery and a repeat evaluation approximately nine months afterward. During the operation, CSF samples were collected to measure Alzheimer’s biomarkers and classify participants as amyloid positive (A+) or amyloid negative (A-).
Overall, the study found that about half of the participants experienced measurable cognitive decline over the follow-up period. Crucially, the pattern of decline differed according to amyloid status. Individuals without abnormal amyloid-β levels tended to show declines in domains such as executive function and constructional praxis—changes likely related to perioperative factors, general vulnerability, or the physiological stresses of surgery. In contrast, participants who had abnormal amyloid-β in their CSF showed a marked worsening of verbal and visual memory—an early and characteristic sign of Alzheimer’s disease.
Carmen Lage noted that before surgery, memory test scores were similar between those with and without abnormal amyloid-β. After surgery, memory performance deteriorated significantly in the amyloid-positive group. These results support the idea that major surgery can lead to different cognitive trajectories depending on preexisting Alzheimer’s pathology: non-memory deficits after surgery in those without amyloid, and memory-centered decline in those with amyloid, consistent with early AD.
Pascual Sánchez-Juan emphasized the clinical relevance as populations age and more frail older adults undergo surgical procedures. Preoperative evaluations typically assess cardiac and respiratory risks but rarely consider the brain’s vulnerability. The study’s findings indicate that including cognitive screening—and, as feasible, Alzheimer’s biomarker assessment—before major surgery could help identify patients at higher risk for postoperative memory decline. This may become more practical as blood-based AD biomarkers become widely available.
About this Alzheimer’s disease research news
Source: IOS Press
Contact: Diana Murray – IOS Press
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Original Research: Closed access. “Major Surgery Affects Memory in Individuals with Cerebral Amyloid-β Pathology” by Carmen Lage et al., Journal of Alzheimer’s Disease
Abstract
Major Surgery Affects Memory in Individuals with Cerebral Amyloid-β Pathology
Background: Major surgery has been linked to perioperative neurocognitive disorders (PND), but the causes and long-term prognosis remain unclear. The authors hypothesized that preclinical Alzheimer’s disease may predispose older adults to cognitive deterioration after surgery.
Objective: To evaluate how amyloid-β pathology affects cognitive outcomes after orthopedic surgery in a cohort of non-demented older adults.
Methods: Non-demented individuals over 65 awaiting orthopedic surgery under spinal anesthesia received neuropsychological testing before surgery and at follow-up. CSF samples taken during surgery were used to measure Alzheimer’s biomarkers and classify participants as amyloid positive (A+) or amyloid negative (A-).
Results: During an average follow-up of nine months, the cumulative incidence of perioperative neurocognitive disorder was 55.2%. The most affected areas across the sample were executive function and constructional praxis. Abnormal amyloid-β levels were associated with postoperative declines in verbal and visual memory. While the A- group showed a pattern similar to the overall sample—with worsened executive function and apparent improvements in memory tests likely driven by practice effects—the A+ group experienced clear memory deterioration.
Conclusion: These findings support the hypothesis that major surgery can promote or accelerate memory decline in cognitively asymptomatic individuals who already have brain amyloid-β deposits. Consideration of cognitive status and Alzheimer’s biomarkers in pre-surgical evaluations may help identify patients at elevated risk for postoperative memory loss.