Development of postoperative delirium remains the strongest predictor of long-term cognitive decline, according to a new study from researchers at Mass General Brigham, Hebrew SeniorLife and Brown University.
The cohort study of 560 older adults, “Rehospitalization and the Association of Postoperative Delirium With Cognitive Decline in Older Adults,” was published this week in JAMA Internal Medicine.
The study sought to answer the question of whether illness and frailty, as measured by rehospitalization, mediate the association of postoperative delirium with cognitive decline in older adults.
“Postoperative delirium is associated with long-term cognitive decline in older adults,” the study states. “This might be caused by the delirium itself or because delirium is more common in persons who are ill and frail, and these conditions are also associated with cognitive decline.”
The study found that “rehospitalization was more common among participants who developed incident postoperative delirium than among those who did not. In those with and without delirium, rehospitalization was associated with cognitive decline, but rehospitalization did not mediate the observed association of delirium with long-term cognitive decline. These findings suggest that postoperative delirium remains the strongest risk factor associated with long-term cognitive decline in older adults.”
The researchers concluded that “contrary to expectations, rehospitalization did not mediate the association between delirium and long-term cognitive decline. Future work will be needed to elucidate the pathways by which delirium is associated with long-term cognitive decline.”
Get access to the full study here.
“Showing that people who develop postoperative delirium decline at a faster pace than those who do not, and this faster decline is not explainable by rehospitalizations during follow-up, reinforces the crucial need to better understand and prevent delirium in older adults," said Zachary J. Kunicki, PhD, MS, MPH, an assistant professor of psychiatry and human behavior at Brown University’s Warren Alpert Medical School who was a first author on the study, and whose comments were published by Brown University.
“We saw that delirium was associated with cognitive decline at a rate faster than what we would normally see with mild cognitive impairment, and the effect was not mediated by rehospitalization,” co-first author Tammy T. Hshieh, MD, MPH, a geriatrician at Mass General Brigham told Brown. “This was surprising because we thought rehospitalization would explain at least some of the effect of delirium on long-term cognitive decline. Future work needs to be done to better understand the important connections between delirium and long-term brain health.”
“We had anticipated that at least part of the effect of delirium on long-term cognition would be due to rehospitalizations which reflected serious medical conditions,” said senior author Sharon K. Inouye, MD, MPH, a professor of medicine at Harvard Medical School and director of the Aging Brain Center at Hebrew Senior Life’s Hinda and Arthur Marcus Institute for Aging Research, told Brown. “However, we were surprised to learn that rehospitalizations did not explain the effects of delirium on subsequent cognitive decline.”
