No More Post-surgery Memory Loss

Scientists discover a receptor that plays a key role in memory impairment after anesthesia administration.

Memory loss after anesthesia may be prevented by blocking a receptor thought to contribute to memory deficits, according to research published in Anesthesiology. The findings indicate that blocking the receptor may also solve the feeling of mental confusion that surgical patients often feel shortly after coming out of anesthesia.

Memory loss after anesthesia often occurs upon awakening from surgery. Currently, there are no known treatments or prevention strategies. Memory impairment most commonly occurs in the elderly. Around 47% of elderly patients who undergo general anesthesia for minor surgical procedures exhibit memory deficits for at least 24 hours after surgery. Some of these deficits can linger: cognitive impairment, including memory loss, is present in 31-47% of patients at the time of hospital discharge.

The recent study was conducted by Beverley A. Orser, MD, PhD, FRCPC, and her research team at Sunnybrook Health Sciences Centre and Mount Sinai Hospital. The team looked at two groups of anesthetized mice - one treated with a drug that inhibits a known memory-blocking receptor, and one treated with a control solution.

“When tested 30 minutes and at one day after anesthetic exposure, the mice in the control group exhibited a memory deficit that was not observed in the mice treated with the blocking compound,” Orser said, in a press release. “We found that the memory deficit in the post-anesthetic period could be completely prevented by treatment with a drug that inhibits the memory-blocking receptor.”

Studies in patients involving anesthetics and their effects on memory are especially difficult, Orser said, because of the inability to disentangle the effects of anesthetics from other factors that can cause memory deficit. Therefore, animal models are important for helping to identify types of learning and memory susceptible to impairment and to identify certain molecular mechanisms.

Orser's study underscores the need for human clinical trials that will assess memory performance soon after surgery.

“In practical terms, our study suggests the need to re-evaluate and study the assumption that patients will remember important information given to them after surgery,” Orser said. “Until such studies are performed, it seems prudent to use strategies such as written information or sharing information with family members to ensure that instructions are learned and remembered.”

The study is titled, “Short-term Memory Impairment after Isoflurane in Mice Is Prevented by the α5 γ-Aminobutyric Acid Type A Receptor Inverse Agonist L-655,708.”

Source: American Society of Anesthesiologists

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