Postoperative Pain may Increase Risk of Cognitive Impairment

Pain experienced following a difficult surgical procedure may impair both learning and cognitive functioning. An animal study from the Massachusetts General Hospital (MGH) looks at a probable mechanism for pain-induced cognitive impairment and suggests possible ways to target potential preventive measures.

"These findings suggest, for the first time, that pain is one of the perioperative factors that contribute to the risk of cognitive dysfunction in surgical patients - in addition to the surgery itself, anesthetics, sleep disturbance and other factors," Zhongcong Xie, MD, PhD, director of the Geriatric Anesthesia Research Unit in the MGH Department of Anesthesia, Critical Care and Pain Medicine said, via a press release. "While postoperative cognitive dysfunction may be temporary, it still can have a major impact on the quality of life of patients and their caregivers at a time when patients' ability to participate in their own care is very important."

Background information from the study notes that up to 80 percent of surgical patients in the United States experience some type of postoperative pain, and several previous studies have suggested that this may harm cognitive functioning.

Rersearchers conducted a number of experiments via a group of mice with small incisions made on one of their paws while under general anesthesia. Following 1,3 and 7 days after the procedure, the animals were then tested for sensitivity to see if the affected foot held any discomfort. Results showed increased sensitivity via a nylon filament in through the area of incision on day 1 and 3 but not the 7^th.

Tests involving learning and memory also showed that the animals who received an incision showed impaired performance on particular tasks at day 3 and 7 but not on day 30. Their ability to remember tasks before the incision was not affected, but their performance to do certain tasks had been diminished following.

"Our findings suggest that inadequate pain treatment may lead to postoperative cognitive dysfunction through a synapse-associated mechanism," Xie said, via the release. "Along with improved pain control, treatments that target inflammation and CDK5 activity could also mitigate the problem. We hope this research will promote more studies into the underlying mechanism of postoperative cognitive dysfunction - specifically whether aged animals have greater pain-associated postoperative impairment - findings of which should ultimately improve outcomes for surgical patients."

More information regarding the study can be found via the Journal of Neuroscience.