About 20-30% of older adults (age greater than 60) undergoing major surgery experience temporary (generally reversed) memory and thinking deficits after major surgery, particularly heart and orthopedic. A small minority (<5%, probably much less) might not return to cognitive baseline (how they were before surgery). The cause of this decline in cognition is unclear, although many attribute it to the anesthesia used. So far, however, research has been inconclusive as to specific causes of cognitive difficulties after surgery. This is because surgeries are major events that affect most parts of the body, not just what is being operated upon. They are stressful – physically and emotionally.
Newly published research proposes one mechanism for causes of memory problems after surgery – anesthesia acting on ɣ-aminobutyric acid type A receptors (ɣ5GABAaR). This new research suggests that the function of these receptors does not return to baseline until much later than previously believed. This means that the normal function of chemicals in the brain, particularly ones important for memory, might be disrupted for longer than expected, and might play a role in memory problems that some individuals experience after major surgery.
Zurek, A. A., Yu, J., Wang, D. S., Haffey, S. C., Bridgwater, E. M., Penna, A., … & Orser, B. A. (2014). Sustained increase in ?5GABA A receptor function impairs memory after anesthesia. The Journal of clinical investigation, 124(12).