Cognitive Decline Associated With Anesthesia and Surgery in Older Patients

Abstract

In the last decade, the population aged 65 years and older increased by 34.2% in the US and now accounts for a disproportionate number of surgical procedures requiring anesthesia. Among these patients, aging causes a number of changes in the brain that may contribute to decreased cognitive reserve, susceptibility to the stresses of surgery and anesthesia, and increased risk of neurologic injury such as postoperative neurocognitive disorders (PNDs). 1 Postoperative neurocognitive disorders is an overarching term that includes postoperative delirium, an acute state of confusion and inattention; and postoperative cognitive dysfunction (POCD), a prolonged state of cognitive impairment that predominantly affects higher-level cognitive skills and memory. Delirium and POCD previously were considered distinct entities, but recent data suggest an underlying relationship between them for the patient whose brain may be vulnerable to cognitivedeclineafterthestressorsofsurgeryandanesthesia.Proposed potential mechanisms for postoperative neurocognitive decline are speculative but include neuroinflammation as a result of perioperative stress, vascular disorders, or the acceleration of neurocognitive decline in patients with a previously undiagnosed neurodegenerative disorder, such as preclinical dementia. According to a study of patients who underwent noncardiac surgery, covert stroke occurred in 7% of 1114 older patients(Ն65years)aftersurgeryandwasassociatedwithanincreased risk of postoperative delirium and long-term cognitive deficits. 2 Among patients aged 65 years and older, up to an estimated 65% experience delirium and 10% develop long-term cognitive decline after noncardiac surgery. 1 Complications associated with delirium include longer hospitalization, more days with mechanical ventilation, and functional decline. After discharge from the hospital, patients who develop postoperative delirium are at increased risk of worsening functional and psychological health, progressive cognitive decline, dementia, and death. Although not as extensively studied as delirium, POCD is associated with a decrease in quality of life, loss of function, and increased mortality.

Postoperative cognitive dysfunction in older surgical patients associated with increased healthcare utilization: a prospective study from an upper-middle-income country

“…POCD was commonly found at approximately 17–43% [ 2 – 4 ], while the POD occurrence accounted for 20–55% [ 5 , 6 ]. Unlike POD, POCD in terms of diagnosis and its consequences is not known widely [ 7 ]. POCD was first described in 1955 [ 8 ].…”

Monocyte NLRP3‐IL‐1β Hyperactivation Mediates Neuronal and Synaptic Dysfunction in Perioperative Neurocognitive Disorder

“…[1] Although most patients quickly regain their cognitive processing, a significant portion of previously DOI: 10.1002/advs.202104106 cognitively well patients develops perioperative neurocognitive disorders (PNDs), which impair postoperative recovery, increase hospital stay and mortality. [2][3][4][5][6] The symptoms of PND include impairments in learning, memory, and psychomotor function, and its duration may vary from days to years. Although more common and severe in elderly patients (>60 years), PND can occur in patients at any ages.…”

α7 Nicotinic Acetylcholine Receptor May Be a Pharmacological Target for Perioperative Neurocognitive Disorders

“…Aging increases the brain susceptibility to the stresses of surgery and anesthesia and impedes cognitive recovery, promoting neurocognitive disorders causing a major concern for these older individuals during postoperative procedures (Vacas et al, 2021). Perioperative neurocognitive disorders (PNDs), including acute postoperative delirium and long-term postoperative cognitive dysfunction, affect functional independence as well as increases mortality (Steinmetz et al, 2009;Leslie, 2017).…”

“…The cholinergic anti-inflammatory pathway can directly modulate the inflammatory response, which is reportedly important in resolving the inflammatory pathogenesis of several diseases, including sepsis, rheumatoid arthritis, and inflammatory bowel disease (Borovikova et al, 2000;Terrando et al, 2011). Furthermore, preoperative anticholinergics (scopolamine) and medications with anticholinergic properties (benzodiazepines) have clinically deleterious effects on neurocognitive function and increase the risk of developing PNDs (Mahanna-Gabrielli et al, 2019;Vacas et al, 2021). Nicotinic acetylcholine receptors (nAChRs) play a central role in the cholinergic pathways.…”