Cognitive Risks After Different Types of Anesthesia

Different types of anesthesia used during surgical procedures may have detrimental effects on cognitive functioning. Studies indicate the effects of anesthetics on the nervous system can impact our brains’ abilities to process and understand information, especially for patients who are already experiencing cognitive decline (5). Factors that impact a patient’s level of cognitive risk include the type of anesthesia that is used for the procedure, the specific analgesic drugs a patient receives, and how the anesthetics are administered. Furthermore, a patient’s age, lifestyle factors, and preexisting comorbidities can also influence their level of cognitive risk.

Patients who undergo surgical procedures may experience a condition called postoperative cognitive dysfunction (POCD), a state of cognitive impairment after a surgical procedure that affects a patient’s executive functioning and memory (1). Most patients who experience postoperative cognitive dysfunction recover within a period of weeks to months, but some patients may suffer from long-term cognitive decline. 

Current scientific knowledge indicates that, among the different types of anesthesia, general anesthesia poses a higher level of cognitive risk. General anesthesia targets receptor proteins in the central nervous system to modify the activities of neurons (5). Patients who undergo general anesthesia can experience lasting cognitive issues, especially with children and the elderly. For example, studies have demonstrated that general anesthesia may have a correlation with cognitive dysfunction in the early postoperative period (6). Studies in rats and non-human primates have also suggested that early exposure to general anesthesia when animals are young can have long-term effects on memory, behavior, and cognitive functioning (5). 

In comparison to general anesthesia, regional anesthesia is considered to pose a lower level of cognitive risk. In one study of patients undergoing elective surgery, those who received regional anesthesia experienced a lower risk of developing dementia than patients who received either inhalation or non-inhalation general anesthesia (3). Accordingly, current scientific knowledge is that regional anesthesia is one of the types of anesthesia with lower cognitive risk. 

The type of analgesic drugs that are used during a procedure and the ways they are administered can also impact a patient’s level of cognitive risk. For example, using multimodal anesthesia, wherein a patient receives a combination of intravenous medications instead of inhalation anesthesia, may reduce a patient’s likelihood of postoperative cognitive dysfunction (2). Similarly, avoiding the use of opioids for pain management postoperatively may protect patients against cognitive decline (2). Narcotics, especially morphine agents, may increase the risk of postoperative cognitive dysfunction, so avoiding them whenever possible can help protect patients’ cognitive function. 

Studies on postoperative cognitive dysfunction continue to dispute the causes behind why some patients experience cognitive decline postoperatively. Aging in particular is a significant factor that has been shown to increase a patient’s vulnerability to the inflammatory effects of surgical procedures and the effects of anesthesia on the nervous system (4). Furthermore, patients who are already on a path of cognitive decline may be more susceptible to postoperative cognitive dysfunction. For example, those with Alzheimer’s disease can be more strongly affected by the neurotoxic effects of surgical stress and anesthesia, which may quicken the rate of cognitive decline (4). Overall, there are many factors that affect cognitive risk after anesthesia, and among the modifiable ones, research suggests that considering different anesthesia types and agents can improve outcomes. 

References 

1. Belrose, Jillian C, and Ruediger R Noppens. “Anesthesiology and cognitive impairment: a narrative review of current clinical literature.” BMC anesthesiology vol. 19,1 241. 27 Dec. 2019, doi:10.1186/s12871-019-0903-7 

1. Subramaniam, Balachundhar and Preeti Upadhyay. “Reducing your risk of changes in thinking following surgery.” Harvard Health Blog, Harvard Health Publishing, May 22 2020. www.health.harvard.edu/blog/reducing-your-risk-of-changes-in-thinking-following-surgery-2020052219898 

2. Sun, Mingyang et al. “Dementia risk after major elective surgery based on the route of anaesthesia: A propensity score-matched population-based cohort study.” EClinicalMedicine vol. 55 101727. 4 Nov. 2022, doi:10.1016/j.eclinm.2022.101727 

3. Vacas, Susana et al. “Cognitive Decline Associated With Anesthesia and Surgery in Older Patients.” JAMA, 10.1001/jama.2021.4773. 2 Aug. 2021, doi:10.1001/jama.2021.4773 

4. Wu, Lingzhi et al. “Lasting effects of general anesthetics on the brain in the young and elderly: “mixed picture” of neurotoxicity, neuroprotection and cognitive impairment.” Journal of anesthesia vol. 33,2 (2019): 321-335. doi:10.1007/s00540-019-02623-7 

5. Zywiel, Michael G et al. “The influence of anesthesia and pain management on cognitive dysfunction after joint arthroplasty: a systematic review.” Clinical orthopaedics and related research vol. 472,5 (2014): 1453-66. doi:10.1007/s11999-013-3363-2